libjpeg update

git-svn-id: http://svn.miranda-ng.org/main/trunk@5843 1316c22d-e87f-b044-9b9b-93d7a3e3ba9c

1 files changed, 857 insertions, 857 deletions

diff --git a/plugins/AdvaImg/src/LibJPEG/jquant1.c b/plugins/AdvaImg/src/LibJPEG/jquant1.c
index 9d11f70669..1c482bc4b1 100644
--- a/plugins/AdvaImg/src/LibJPEG/jquant1.c
+++ b/plugins/AdvaImg/src/LibJPEG/jquant1.c
@@ -1,857 +1,857 @@
-/*
- * jquant1.c
- *
- * Copyright (C) 1991-1996, Thomas G. Lane.
- * Modified 2011 by Guido Vollbeding.
- * This file is part of the Independent JPEG Group's software.
- * For conditions of distribution and use, see the accompanying README file.
- *
- * This file contains 1-pass color quantization (color mapping) routines.
- * These routines provide mapping to a fixed color map using equally spaced
- * color values.  Optional Floyd-Steinberg or ordered dithering is available.
- */
-
-#define JPEG_INTERNALS
-#include "jinclude.h"
-#include "jpeglib.h"
-
-#ifdef QUANT_1PASS_SUPPORTED
-
-
-/*
- * The main purpose of 1-pass quantization is to provide a fast, if not very
- * high quality, colormapped output capability.  A 2-pass quantizer usually
- * gives better visual quality; however, for quantized grayscale output this
- * quantizer is perfectly adequate.  Dithering is highly recommended with this
- * quantizer, though you can turn it off if you really want to.
- *
- * In 1-pass quantization the colormap must be chosen in advance of seeing the
- * image.  We use a map consisting of all combinations of Ncolors[i] color
- * values for the i'th component.  The Ncolors[] values are chosen so that
- * their product, the total number of colors, is no more than that requested.
- * (In most cases, the product will be somewhat less.)
- *
- * Since the colormap is orthogonal, the representative value for each color
- * component can be determined without considering the other components;
- * then these indexes can be combined into a colormap index by a standard
- * N-dimensional-array-subscript calculation.  Most of the arithmetic involved
- * can be precalculated and stored in the lookup table colorindex[].
- * colorindex[i][j] maps pixel value j in component i to the nearest
- * representative value (grid plane) for that component; this index is
- * multiplied by the array stride for component i, so that the
- * index of the colormap entry closest to a given pixel value is just
- *    sum( colorindex[component-number][pixel-component-value] )
- * Aside from being fast, this scheme allows for variable spacing between
- * representative values with no additional lookup cost.
- *
- * If gamma correction has been applied in color conversion, it might be wise
- * to adjust the color grid spacing so that the representative colors are
- * equidistant in linear space.  At this writing, gamma correction is not
- * implemented by jdcolor, so nothing is done here.
- */
-
-
-/* Declarations for ordered dithering.
- *
- * We use a standard 16x16 ordered dither array.  The basic concept of ordered
- * dithering is described in many references, for instance Dale Schumacher's
- * chapter II.2 of Graphics Gems II (James Arvo, ed. Academic Press, 1991).
- * In place of Schumacher's comparisons against a "threshold" value, we add a
- * "dither" value to the input pixel and then round the result to the nearest
- * output value.  The dither value is equivalent to (0.5 - threshold) times
- * the distance between output values.  For ordered dithering, we assume that
- * the output colors are equally spaced; if not, results will probably be
- * worse, since the dither may be too much or too little at a given point.
- *
- * The normal calculation would be to form pixel value + dither, range-limit
- * this to 0..MAXJSAMPLE, and then index into the colorindex table as usual.
- * We can skip the separate range-limiting step by extending the colorindex
- * table in both directions.
- */
-
-#define ODITHER_SIZE  16	/* dimension of dither matrix */
-/* NB: if ODITHER_SIZE is not a power of 2, ODITHER_MASK uses will break */
-#define ODITHER_CELLS (ODITHER_SIZE*ODITHER_SIZE)	/* # cells in matrix */
-#define ODITHER_MASK  (ODITHER_SIZE-1) /* mask for wrapping around counters */
-
-typedef int ODITHER_MATRIX[ODITHER_SIZE][ODITHER_SIZE];
-typedef int (*ODITHER_MATRIX_PTR)[ODITHER_SIZE];
-
-static const UINT8 base_dither_matrix[ODITHER_SIZE][ODITHER_SIZE] = {
-  /* Bayer's order-4 dither array.  Generated by the code given in
-   * Stephen Hawley's article "Ordered Dithering" in Graphics Gems I.
-   * The values in this array must range from 0 to ODITHER_CELLS-1.
-   */
-  {   0,192, 48,240, 12,204, 60,252,  3,195, 51,243, 15,207, 63,255 },
-  { 128, 64,176,112,140, 76,188,124,131, 67,179,115,143, 79,191,127 },
-  {  32,224, 16,208, 44,236, 28,220, 35,227, 19,211, 47,239, 31,223 },
-  { 160, 96,144, 80,172,108,156, 92,163, 99,147, 83,175,111,159, 95 },
-  {   8,200, 56,248,  4,196, 52,244, 11,203, 59,251,  7,199, 55,247 },
-  { 136, 72,184,120,132, 68,180,116,139, 75,187,123,135, 71,183,119 },
-  {  40,232, 24,216, 36,228, 20,212, 43,235, 27,219, 39,231, 23,215 },
-  { 168,104,152, 88,164,100,148, 84,171,107,155, 91,167,103,151, 87 },
-  {   2,194, 50,242, 14,206, 62,254,  1,193, 49,241, 13,205, 61,253 },
-  { 130, 66,178,114,142, 78,190,126,129, 65,177,113,141, 77,189,125 },
-  {  34,226, 18,210, 46,238, 30,222, 33,225, 17,209, 45,237, 29,221 },
-  { 162, 98,146, 82,174,110,158, 94,161, 97,145, 81,173,109,157, 93 },
-  {  10,202, 58,250,  6,198, 54,246,  9,201, 57,249,  5,197, 53,245 },
-  { 138, 74,186,122,134, 70,182,118,137, 73,185,121,133, 69,181,117 },
-  {  42,234, 26,218, 38,230, 22,214, 41,233, 25,217, 37,229, 21,213 },
-  { 170,106,154, 90,166,102,150, 86,169,105,153, 89,165,101,149, 85 }
-};
-
-
-/* Declarations for Floyd-Steinberg dithering.
- *
- * Errors are accumulated into the array fserrors[], at a resolution of
- * 1/16th of a pixel count.  The error at a given pixel is propagated
- * to its not-yet-processed neighbors using the standard F-S fractions,
- *		...	(here)	7/16
- *		3/16	5/16	1/16
- * We work left-to-right on even rows, right-to-left on odd rows.
- *
- * We can get away with a single array (holding one row's worth of errors)
- * by using it to store the current row's errors at pixel columns not yet
- * processed, but the next row's errors at columns already processed.  We
- * need only a few extra variables to hold the errors immediately around the
- * current column.  (If we are lucky, those variables are in registers, but
- * even if not, they're probably cheaper to access than array elements are.)
- *
- * The fserrors[] array is indexed [component#][position].
- * We provide (#columns + 2) entries per component; the extra entry at each
- * end saves us from special-casing the first and last pixels.
- *
- * Note: on a wide image, we might not have enough room in a PC's near data
- * segment to hold the error array; so it is allocated with alloc_large.
- */
-
-#if BITS_IN_JSAMPLE == 8
-typedef INT16 FSERROR;		/* 16 bits should be enough */
-typedef int LOCFSERROR;		/* use 'int' for calculation temps */
-#else
-typedef INT32 FSERROR;		/* may need more than 16 bits */
-typedef INT32 LOCFSERROR;	/* be sure calculation temps are big enough */
-#endif
-
-typedef FSERROR FAR *FSERRPTR;	/* pointer to error array (in FAR storage!) */
-
-
-/* Private subobject */
-
-#define MAX_Q_COMPS 4		/* max components I can handle */
-
-typedef struct {
-  struct jpeg_color_quantizer pub; /* public fields */
-
-  /* Initially allocated colormap is saved here */
-  JSAMPARRAY sv_colormap;	/* The color map as a 2-D pixel array */
-  int sv_actual;		/* number of entries in use */
-
-  JSAMPARRAY colorindex;	/* Precomputed mapping for speed */
-  /* colorindex[i][j] = index of color closest to pixel value j in component i,
-   * premultiplied as described above.  Since colormap indexes must fit into
-   * JSAMPLEs, the entries of this array will too.
-   */
-  boolean is_padded;		/* is the colorindex padded for odither? */
-
-  int Ncolors[MAX_Q_COMPS];	/* # of values alloced to each component */
-
-  /* Variables for ordered dithering */
-  int row_index;		/* cur row's vertical index in dither matrix */
-  ODITHER_MATRIX_PTR odither[MAX_Q_COMPS]; /* one dither array per component */
-
-  /* Variables for Floyd-Steinberg dithering */
-  FSERRPTR fserrors[MAX_Q_COMPS]; /* accumulated errors */
-  boolean on_odd_row;		/* flag to remember which row we are on */
-} my_cquantizer;
-
-typedef my_cquantizer * my_cquantize_ptr;
-
-
-/*
- * Policy-making subroutines for create_colormap and create_colorindex.
- * These routines determine the colormap to be used.  The rest of the module
- * only assumes that the colormap is orthogonal.
- *
- *  * select_ncolors decides how to divvy up the available colors
- *    among the components.
- *  * output_value defines the set of representative values for a component.
- *  * largest_input_value defines the mapping from input values to
- *    representative values for a component.
- * Note that the latter two routines may impose different policies for
- * different components, though this is not currently done.
- */
-
-
-LOCAL(int)
-select_ncolors (j_decompress_ptr cinfo, int Ncolors[])
-/* Determine allocation of desired colors to components, */
-/* and fill in Ncolors[] array to indicate choice. */
-/* Return value is total number of colors (product of Ncolors[] values). */
-{
-  int nc = cinfo->out_color_components; /* number of color components */
-  int max_colors = cinfo->desired_number_of_colors;
-  int total_colors, iroot, i, j;
-  boolean changed;
-  long temp;
-  static const int RGB_order[3] = { RGB_GREEN, RGB_RED, RGB_BLUE };
-
-  /* We can allocate at least the nc'th root of max_colors per component. */
-  /* Compute floor(nc'th root of max_colors). */
-  iroot = 1;
-  do {
-    iroot++;
-    temp = iroot;		/* set temp = iroot ** nc */
-    for (i = 1; i < nc; i++)
-      temp *= iroot;
-  } while (temp <= (long) max_colors); /* repeat till iroot exceeds root */
-  iroot--;			/* now iroot = floor(root) */
-
-  /* Must have at least 2 color values per component */
-  if (iroot < 2)
-    ERREXIT1(cinfo, JERR_QUANT_FEW_COLORS, (int) temp);
-
-  /* Initialize to iroot color values for each component */
-  total_colors = 1;
-  for (i = 0; i < nc; i++) {
-    Ncolors[i] = iroot;
-    total_colors *= iroot;
-  }
-  /* We may be able to increment the count for one or more components without
-   * exceeding max_colors, though we know not all can be incremented.
-   * Sometimes, the first component can be incremented more than once!
-   * (Example: for 16 colors, we start at 2*2*2, go to 3*2*2, then 4*2*2.)
-   * In RGB colorspace, try to increment G first, then R, then B.
-   */
-  do {
-    changed = FALSE;
-    for (i = 0; i < nc; i++) {
-      j = (cinfo->out_color_space == JCS_RGB ? RGB_order[i] : i);
-      /* calculate new total_colors if Ncolors[j] is incremented */
-      temp = total_colors / Ncolors[j];
-      temp *= Ncolors[j]+1;	/* done in long arith to avoid oflo */
-      if (temp > (long) max_colors)
-	break;			/* won't fit, done with this pass */
-      Ncolors[j]++;		/* OK, apply the increment */
-      total_colors = (int) temp;
-      changed = TRUE;
-    }
-  } while (changed);
-
-  return total_colors;
-}
-
-
-LOCAL(int)
-output_value (j_decompress_ptr cinfo, int ci, int j, int maxj)
-/* Return j'th output value, where j will range from 0 to maxj */
-/* The output values must fall in 0..MAXJSAMPLE in increasing order */
-{
-  /* We always provide values 0 and MAXJSAMPLE for each component;
-   * any additional values are equally spaced between these limits.
-   * (Forcing the upper and lower values to the limits ensures that
-   * dithering can't produce a color outside the selected gamut.)
-   */
-  return (int) (((INT32) j * MAXJSAMPLE + maxj/2) / maxj);
-}
-
-
-LOCAL(int)
-largest_input_value (j_decompress_ptr cinfo, int ci, int j, int maxj)
-/* Return largest input value that should map to j'th output value */
-/* Must have largest(j=0) >= 0, and largest(j=maxj) >= MAXJSAMPLE */
-{
-  /* Breakpoints are halfway between values returned by output_value */
-  return (int) (((INT32) (2*j + 1) * MAXJSAMPLE + maxj) / (2*maxj));
-}
-
-
-/*
- * Create the colormap.
- */
-
-LOCAL(void)
-create_colormap (j_decompress_ptr cinfo)
-{
-  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
-  JSAMPARRAY colormap;		/* Created colormap */
-  int total_colors;		/* Number of distinct output colors */
-  int i,j,k, nci, blksize, blkdist, ptr, val;
-
-  /* Select number of colors for each component */
-  total_colors = select_ncolors(cinfo, cquantize->Ncolors);
-
-  /* Report selected color counts */
-  if (cinfo->out_color_components == 3)
-    TRACEMS4(cinfo, 1, JTRC_QUANT_3_NCOLORS,
-	     total_colors, cquantize->Ncolors[0],
-	     cquantize->Ncolors[1], cquantize->Ncolors[2]);
-  else
-    TRACEMS1(cinfo, 1, JTRC_QUANT_NCOLORS, total_colors);
-
-  /* Allocate and fill in the colormap. */
-  /* The colors are ordered in the map in standard row-major order, */
-  /* i.e. rightmost (highest-indexed) color changes most rapidly. */
-
-  colormap = (*cinfo->mem->alloc_sarray)
-    ((j_common_ptr) cinfo, JPOOL_IMAGE,
-     (JDIMENSION) total_colors, (JDIMENSION) cinfo->out_color_components);
-
-  /* blksize is number of adjacent repeated entries for a component */
-  /* blkdist is distance between groups of identical entries for a component */
-  blkdist = total_colors;
-
-  for (i = 0; i < cinfo->out_color_components; i++) {
-    /* fill in colormap entries for i'th color component */
-    nci = cquantize->Ncolors[i]; /* # of distinct values for this color */
-    blksize = blkdist / nci;
-    for (j = 0; j < nci; j++) {
-      /* Compute j'th output value (out of nci) for component */
-      val = output_value(cinfo, i, j, nci-1);
-      /* Fill in all colormap entries that have this value of this component */
-      for (ptr = j * blksize; ptr < total_colors; ptr += blkdist) {
-	/* fill in blksize entries beginning at ptr */
-	for (k = 0; k < blksize; k++)
-	  colormap[i][ptr+k] = (JSAMPLE) val;
-      }
-    }
-    blkdist = blksize;		/* blksize of this color is blkdist of next */
-  }
-
-  /* Save the colormap in private storage,
-   * where it will survive color quantization mode changes.
-   */
-  cquantize->sv_colormap = colormap;
-  cquantize->sv_actual = total_colors;
-}
-
-
-/*
- * Create the color index table.
- */
-
-LOCAL(void)
-create_colorindex (j_decompress_ptr cinfo)
-{
-  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
-  JSAMPROW indexptr;
-  int i,j,k, nci, blksize, val, pad;
-
-  /* For ordered dither, we pad the color index tables by MAXJSAMPLE in
-   * each direction (input index values can be -MAXJSAMPLE .. 2*MAXJSAMPLE).
-   * This is not necessary in the other dithering modes.  However, we
-   * flag whether it was done in case user changes dithering mode.
-   */
-  if (cinfo->dither_mode == JDITHER_ORDERED) {
-    pad = MAXJSAMPLE*2;
-    cquantize->is_padded = TRUE;
-  } else {
-    pad = 0;
-    cquantize->is_padded = FALSE;
-  }
-
-  cquantize->colorindex = (*cinfo->mem->alloc_sarray)
-    ((j_common_ptr) cinfo, JPOOL_IMAGE,
-     (JDIMENSION) (MAXJSAMPLE+1 + pad),
-     (JDIMENSION) cinfo->out_color_components);
-
-  /* blksize is number of adjacent repeated entries for a component */
-  blksize = cquantize->sv_actual;
-
-  for (i = 0; i < cinfo->out_color_components; i++) {
-    /* fill in colorindex entries for i'th color component */
-    nci = cquantize->Ncolors[i]; /* # of distinct values for this color */
-    blksize = blksize / nci;
-
-    /* adjust colorindex pointers to provide padding at negative indexes. */
-    if (pad)
-      cquantize->colorindex[i] += MAXJSAMPLE;
-
-    /* in loop, val = index of current output value, */
-    /* and k = largest j that maps to current val */
-    indexptr = cquantize->colorindex[i];
-    val = 0;
-    k = largest_input_value(cinfo, i, 0, nci-1);
-    for (j = 0; j <= MAXJSAMPLE; j++) {
-      while (j > k)		/* advance val if past boundary */
-	k = largest_input_value(cinfo, i, ++val, nci-1);
-      /* premultiply so that no multiplication needed in main processing */
-      indexptr[j] = (JSAMPLE) (val * blksize);
-    }
-    /* Pad at both ends if necessary */
-    if (pad)
-      for (j = 1; j <= MAXJSAMPLE; j++) {
-	indexptr[-j] = indexptr[0];
-	indexptr[MAXJSAMPLE+j] = indexptr[MAXJSAMPLE];
-      }
-  }
-}
-
-
-/*
- * Create an ordered-dither array for a component having ncolors
- * distinct output values.
- */
-
-LOCAL(ODITHER_MATRIX_PTR)
-make_odither_array (j_decompress_ptr cinfo, int ncolors)
-{
-  ODITHER_MATRIX_PTR odither;
-  int j,k;
-  INT32 num,den;
-
-  odither = (ODITHER_MATRIX_PTR)
-    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
-				SIZEOF(ODITHER_MATRIX));
-  /* The inter-value distance for this color is MAXJSAMPLE/(ncolors-1).
-   * Hence the dither value for the matrix cell with fill order f
-   * (f=0..N-1) should be (N-1-2*f)/(2*N) * MAXJSAMPLE/(ncolors-1).
-   * On 16-bit-int machine, be careful to avoid overflow.
-   */
-  den = 2 * ODITHER_CELLS * ((INT32) (ncolors - 1));
-  for (j = 0; j < ODITHER_SIZE; j++) {
-    for (k = 0; k < ODITHER_SIZE; k++) {
-      num = ((INT32) (ODITHER_CELLS-1 - 2*((int)base_dither_matrix[j][k])))
-	    * MAXJSAMPLE;
-      /* Ensure round towards zero despite C's lack of consistency
-       * about rounding negative values in integer division...
-       */
-      odither[j][k] = (int) (num<0 ? -((-num)/den) : num/den);
-    }
-  }
-  return odither;
-}
-
-
-/*
- * Create the ordered-dither tables.
- * Components having the same number of representative colors may 
- * share a dither table.
- */
-
-LOCAL(void)
-create_odither_tables (j_decompress_ptr cinfo)
-{
-  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
-  ODITHER_MATRIX_PTR odither;
-  int i, j, nci;
-
-  for (i = 0; i < cinfo->out_color_components; i++) {
-    nci = cquantize->Ncolors[i]; /* # of distinct values for this color */
-    odither = NULL;		/* search for matching prior component */
-    for (j = 0; j < i; j++) {
-      if (nci == cquantize->Ncolors[j]) {
-	odither = cquantize->odither[j];
-	break;
-      }
-    }
-    if (odither == NULL)	/* need a new table? */
-      odither = make_odither_array(cinfo, nci);
-    cquantize->odither[i] = odither;
-  }
-}
-
-
-/*
- * Map some rows of pixels to the output colormapped representation.
- */
-
-METHODDEF(void)
-color_quantize (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
-		JSAMPARRAY output_buf, int num_rows)
-/* General case, no dithering */
-{
-  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
-  JSAMPARRAY colorindex = cquantize->colorindex;
-  register int pixcode, ci;
-  register JSAMPROW ptrin, ptrout;
-  int row;
-  JDIMENSION col;
-  JDIMENSION width = cinfo->output_width;
-  register int nc = cinfo->out_color_components;
-
-  for (row = 0; row < num_rows; row++) {
-    ptrin = input_buf[row];
-    ptrout = output_buf[row];
-    for (col = width; col > 0; col--) {
-      pixcode = 0;
-      for (ci = 0; ci < nc; ci++) {
-	pixcode += GETJSAMPLE(colorindex[ci][GETJSAMPLE(*ptrin++)]);
-      }
-      *ptrout++ = (JSAMPLE) pixcode;
-    }
-  }
-}
-
-
-METHODDEF(void)
-color_quantize3 (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
-		 JSAMPARRAY output_buf, int num_rows)
-/* Fast path for out_color_components==3, no dithering */
-{
-  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
-  register int pixcode;
-  register JSAMPROW ptrin, ptrout;
-  JSAMPROW colorindex0 = cquantize->colorindex[0];
-  JSAMPROW colorindex1 = cquantize->colorindex[1];
-  JSAMPROW colorindex2 = cquantize->colorindex[2];
-  int row;
-  JDIMENSION col;
-  JDIMENSION width = cinfo->output_width;
-
-  for (row = 0; row < num_rows; row++) {
-    ptrin = input_buf[row];
-    ptrout = output_buf[row];
-    for (col = width; col > 0; col--) {
-      pixcode  = GETJSAMPLE(colorindex0[GETJSAMPLE(*ptrin++)]);
-      pixcode += GETJSAMPLE(colorindex1[GETJSAMPLE(*ptrin++)]);
-      pixcode += GETJSAMPLE(colorindex2[GETJSAMPLE(*ptrin++)]);
-      *ptrout++ = (JSAMPLE) pixcode;
-    }
-  }
-}
-
-
-METHODDEF(void)
-quantize_ord_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
-		     JSAMPARRAY output_buf, int num_rows)
-/* General case, with ordered dithering */
-{
-  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
-  register JSAMPROW input_ptr;
-  register JSAMPROW output_ptr;
-  JSAMPROW colorindex_ci;
-  int * dither;			/* points to active row of dither matrix */
-  int row_index, col_index;	/* current indexes into dither matrix */
-  int nc = cinfo->out_color_components;
-  int ci;
-  int row;
-  JDIMENSION col;
-  JDIMENSION width = cinfo->output_width;
-
-  for (row = 0; row < num_rows; row++) {
-    /* Initialize output values to 0 so can process components separately */
-    FMEMZERO((void FAR *) output_buf[row],
-	     (size_t) (width * SIZEOF(JSAMPLE)));
-    row_index = cquantize->row_index;
-    for (ci = 0; ci < nc; ci++) {
-      input_ptr = input_buf[row] + ci;
-      output_ptr = output_buf[row];
-      colorindex_ci = cquantize->colorindex[ci];
-      dither = cquantize->odither[ci][row_index];
-      col_index = 0;
-
-      for (col = width; col > 0; col--) {
-	/* Form pixel value + dither, range-limit to 0..MAXJSAMPLE,
-	 * select output value, accumulate into output code for this pixel.
-	 * Range-limiting need not be done explicitly, as we have extended
-	 * the colorindex table to produce the right answers for out-of-range
-	 * inputs.  The maximum dither is +- MAXJSAMPLE; this sets the
-	 * required amount of padding.
-	 */
-	*output_ptr += colorindex_ci[GETJSAMPLE(*input_ptr)+dither[col_index]];
-	input_ptr += nc;
-	output_ptr++;
-	col_index = (col_index + 1) & ODITHER_MASK;
-      }
-    }
-    /* Advance row index for next row */
-    row_index = (row_index + 1) & ODITHER_MASK;
-    cquantize->row_index = row_index;
-  }
-}
-
-
-METHODDEF(void)
-quantize3_ord_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
-		      JSAMPARRAY output_buf, int num_rows)
-/* Fast path for out_color_components==3, with ordered dithering */
-{
-  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
-  register int pixcode;
-  register JSAMPROW input_ptr;
-  register JSAMPROW output_ptr;
-  JSAMPROW colorindex0 = cquantize->colorindex[0];
-  JSAMPROW colorindex1 = cquantize->colorindex[1];
-  JSAMPROW colorindex2 = cquantize->colorindex[2];
-  int * dither0;		/* points to active row of dither matrix */
-  int * dither1;
-  int * dither2;
-  int row_index, col_index;	/* current indexes into dither matrix */
-  int row;
-  JDIMENSION col;
-  JDIMENSION width = cinfo->output_width;
-
-  for (row = 0; row < num_rows; row++) {
-    row_index = cquantize->row_index;
-    input_ptr = input_buf[row];
-    output_ptr = output_buf[row];
-    dither0 = cquantize->odither[0][row_index];
-    dither1 = cquantize->odither[1][row_index];
-    dither2 = cquantize->odither[2][row_index];
-    col_index = 0;
-
-    for (col = width; col > 0; col--) {
-      pixcode  = GETJSAMPLE(colorindex0[GETJSAMPLE(*input_ptr++) +
-					dither0[col_index]]);
-      pixcode += GETJSAMPLE(colorindex1[GETJSAMPLE(*input_ptr++) +
-					dither1[col_index]]);
-      pixcode += GETJSAMPLE(colorindex2[GETJSAMPLE(*input_ptr++) +
-					dither2[col_index]]);
-      *output_ptr++ = (JSAMPLE) pixcode;
-      col_index = (col_index + 1) & ODITHER_MASK;
-    }
-    row_index = (row_index + 1) & ODITHER_MASK;
-    cquantize->row_index = row_index;
-  }
-}
-
-
-METHODDEF(void)
-quantize_fs_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
-		    JSAMPARRAY output_buf, int num_rows)
-/* General case, with Floyd-Steinberg dithering */
-{
-  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
-  register LOCFSERROR cur;	/* current error or pixel value */
-  LOCFSERROR belowerr;		/* error for pixel below cur */
-  LOCFSERROR bpreverr;		/* error for below/prev col */
-  LOCFSERROR bnexterr;		/* error for below/next col */
-  LOCFSERROR delta;
-  register FSERRPTR errorptr;	/* => fserrors[] at column before current */
-  register JSAMPROW input_ptr;
-  register JSAMPROW output_ptr;
-  JSAMPROW colorindex_ci;
-  JSAMPROW colormap_ci;
-  int pixcode;
-  int nc = cinfo->out_color_components;
-  int dir;			/* 1 for left-to-right, -1 for right-to-left */
-  int dirnc;			/* dir * nc */
-  int ci;
-  int row;
-  JDIMENSION col;
-  JDIMENSION width = cinfo->output_width;
-  JSAMPLE *range_limit = cinfo->sample_range_limit;
-  SHIFT_TEMPS
-
-  for (row = 0; row < num_rows; row++) {
-    /* Initialize output values to 0 so can process components separately */
-    FMEMZERO((void FAR *) output_buf[row],
-	     (size_t) (width * SIZEOF(JSAMPLE)));
-    for (ci = 0; ci < nc; ci++) {
-      input_ptr = input_buf[row] + ci;
-      output_ptr = output_buf[row];
-      if (cquantize->on_odd_row) {
-	/* work right to left in this row */
-	input_ptr += (width-1) * nc; /* so point to rightmost pixel */
-	output_ptr += width-1;
-	dir = -1;
-	dirnc = -nc;
-	errorptr = cquantize->fserrors[ci] + (width+1); /* => entry after last column */
-      } else {
-	/* work left to right in this row */
-	dir = 1;
-	dirnc = nc;
-	errorptr = cquantize->fserrors[ci]; /* => entry before first column */
-      }
-      colorindex_ci = cquantize->colorindex[ci];
-      colormap_ci = cquantize->sv_colormap[ci];
-      /* Preset error values: no error propagated to first pixel from left */
-      cur = 0;
-      /* and no error propagated to row below yet */
-      belowerr = bpreverr = 0;
-
-      for (col = width; col > 0; col--) {
-	/* cur holds the error propagated from the previous pixel on the
-	 * current line.  Add the error propagated from the previous line
-	 * to form the complete error correction term for this pixel, and
-	 * round the error term (which is expressed * 16) to an integer.
-	 * RIGHT_SHIFT rounds towards minus infinity, so adding 8 is correct
-	 * for either sign of the error value.
-	 * Note: errorptr points to *previous* column's array entry.
-	 */
-	cur = RIGHT_SHIFT(cur + errorptr[dir] + 8, 4);
-	/* Form pixel value + error, and range-limit to 0..MAXJSAMPLE.
-	 * The maximum error is +- MAXJSAMPLE; this sets the required size
-	 * of the range_limit array.
-	 */
-	cur += GETJSAMPLE(*input_ptr);
-	cur = GETJSAMPLE(range_limit[cur]);
-	/* Select output value, accumulate into output code for this pixel */
-	pixcode = GETJSAMPLE(colorindex_ci[cur]);
-	*output_ptr += (JSAMPLE) pixcode;
-	/* Compute actual representation error at this pixel */
-	/* Note: we can do this even though we don't have the final */
-	/* pixel code, because the colormap is orthogonal. */
-	cur -= GETJSAMPLE(colormap_ci[pixcode]);
-	/* Compute error fractions to be propagated to adjacent pixels.
-	 * Add these into the running sums, and simultaneously shift the
-	 * next-line error sums left by 1 column.
-	 */
-	bnexterr = cur;
-	delta = cur * 2;
-	cur += delta;		/* form error * 3 */
-	errorptr[0] = (FSERROR) (bpreverr + cur);
-	cur += delta;		/* form error * 5 */
-	bpreverr = belowerr + cur;
-	belowerr = bnexterr;
-	cur += delta;		/* form error * 7 */
-	/* At this point cur contains the 7/16 error value to be propagated
-	 * to the next pixel on the current line, and all the errors for the
-	 * next line have been shifted over. We are therefore ready to move on.
-	 */
-	input_ptr += dirnc;	/* advance input ptr to next column */
-	output_ptr += dir;	/* advance output ptr to next column */
-	errorptr += dir;	/* advance errorptr to current column */
-      }
-      /* Post-loop cleanup: we must unload the final error value into the
-       * final fserrors[] entry.  Note we need not unload belowerr because
-       * it is for the dummy column before or after the actual array.
-       */
-      errorptr[0] = (FSERROR) bpreverr; /* unload prev err into array */
-    }
-    cquantize->on_odd_row = (cquantize->on_odd_row ? FALSE : TRUE);
-  }
-}
-
-
-/*
- * Allocate workspace for Floyd-Steinberg errors.
- */
-
-LOCAL(void)
-alloc_fs_workspace (j_decompress_ptr cinfo)
-{
-  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
-  size_t arraysize;
-  int i;
-
-  arraysize = (size_t) ((cinfo->output_width + 2) * SIZEOF(FSERROR));
-  for (i = 0; i < cinfo->out_color_components; i++) {
-    cquantize->fserrors[i] = (FSERRPTR)
-      (*cinfo->mem->alloc_large)((j_common_ptr) cinfo, JPOOL_IMAGE, arraysize);
-  }
-}
-
-
-/*
- * Initialize for one-pass color quantization.
- */
-
-METHODDEF(void)
-start_pass_1_quant (j_decompress_ptr cinfo, boolean is_pre_scan)
-{
-  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
-  size_t arraysize;
-  int i;
-
-  /* Install my colormap. */
-  cinfo->colormap = cquantize->sv_colormap;
-  cinfo->actual_number_of_colors = cquantize->sv_actual;
-
-  /* Initialize for desired dithering mode. */
-  switch (cinfo->dither_mode) {
-  case JDITHER_NONE:
-    if (cinfo->out_color_components == 3)
-      cquantize->pub.color_quantize = color_quantize3;
-    else
-      cquantize->pub.color_quantize = color_quantize;
-    break;
-  case JDITHER_ORDERED:
-    if (cinfo->out_color_components == 3)
-      cquantize->pub.color_quantize = quantize3_ord_dither;
-    else
-      cquantize->pub.color_quantize = quantize_ord_dither;
-    cquantize->row_index = 0;	/* initialize state for ordered dither */
-    /* If user changed to ordered dither from another mode,
-     * we must recreate the color index table with padding.
-     * This will cost extra space, but probably isn't very likely.
-     */
-    if (! cquantize->is_padded)
-      create_colorindex(cinfo);
-    /* Create ordered-dither tables if we didn't already. */
-    if (cquantize->odither[0] == NULL)
-      create_odither_tables(cinfo);
-    break;
-  case JDITHER_FS:
-    cquantize->pub.color_quantize = quantize_fs_dither;
-    cquantize->on_odd_row = FALSE; /* initialize state for F-S dither */
-    /* Allocate Floyd-Steinberg workspace if didn't already. */
-    if (cquantize->fserrors[0] == NULL)
-      alloc_fs_workspace(cinfo);
-    /* Initialize the propagated errors to zero. */
-    arraysize = (size_t) ((cinfo->output_width + 2) * SIZEOF(FSERROR));
-    for (i = 0; i < cinfo->out_color_components; i++)
-      FMEMZERO((void FAR *) cquantize->fserrors[i], arraysize);
-    break;
-  default:
-    ERREXIT(cinfo, JERR_NOT_COMPILED);
-    break;
-  }
-}
-
-
-/*
- * Finish up at the end of the pass.
- */
-
-METHODDEF(void)
-finish_pass_1_quant (j_decompress_ptr cinfo)
-{
-  /* no work in 1-pass case */
-}
-
-
-/*
- * Switch to a new external colormap between output passes.
- * Shouldn't get to this module!
- */
-
-METHODDEF(void)
-new_color_map_1_quant (j_decompress_ptr cinfo)
-{
-  ERREXIT(cinfo, JERR_MODE_CHANGE);
-}
-
-
-/*
- * Module initialization routine for 1-pass color quantization.
- */
-
-GLOBAL(void)
-jinit_1pass_quantizer (j_decompress_ptr cinfo)
-{
-  my_cquantize_ptr cquantize;
-
-  cquantize = (my_cquantize_ptr)
-    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
-				SIZEOF(my_cquantizer));
-  cinfo->cquantize = (struct jpeg_color_quantizer *) cquantize;
-  cquantize->pub.start_pass = start_pass_1_quant;
-  cquantize->pub.finish_pass = finish_pass_1_quant;
-  cquantize->pub.new_color_map = new_color_map_1_quant;
-  cquantize->fserrors[0] = NULL; /* Flag FS workspace not allocated */
-  cquantize->odither[0] = NULL;	/* Also flag odither arrays not allocated */
-
-  /* Make sure my internal arrays won't overflow */
-  if (cinfo->out_color_components > MAX_Q_COMPS)
-    ERREXIT1(cinfo, JERR_QUANT_COMPONENTS, MAX_Q_COMPS);
-  /* Make sure colormap indexes can be represented by JSAMPLEs */
-  if (cinfo->desired_number_of_colors > (MAXJSAMPLE+1))
-    ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, MAXJSAMPLE+1);
-
-  /* Create the colormap and color index table. */
-  create_colormap(cinfo);
-  create_colorindex(cinfo);
-
-  /* Allocate Floyd-Steinberg workspace now if requested.
-   * We do this now since it is FAR storage and may affect the memory
-   * manager's space calculations.  If the user changes to FS dither
-   * mode in a later pass, we will allocate the space then, and will
-   * possibly overrun the max_memory_to_use setting.
-   */
-  if (cinfo->dither_mode == JDITHER_FS)
-    alloc_fs_workspace(cinfo);
-}
-
-#endif /* QUANT_1PASS_SUPPORTED */
+/*

+ * jquant1.c

+ *

+ * Copyright (C) 1991-1996, Thomas G. Lane.

+ * Modified 2011 by Guido Vollbeding.

+ * This file is part of the Independent JPEG Group's software.

+ * For conditions of distribution and use, see the accompanying README file.

+ *

+ * This file contains 1-pass color quantization (color mapping) routines.

+ * These routines provide mapping to a fixed color map using equally spaced

+ * color values.  Optional Floyd-Steinberg or ordered dithering is available.

+ */

+

+#define JPEG_INTERNALS

+#include "jinclude.h"

+#include "jpeglib.h"

+

+#ifdef QUANT_1PASS_SUPPORTED

+

+

+/*

+ * The main purpose of 1-pass quantization is to provide a fast, if not very

+ * high quality, colormapped output capability.  A 2-pass quantizer usually

+ * gives better visual quality; however, for quantized grayscale output this

+ * quantizer is perfectly adequate.  Dithering is highly recommended with this

+ * quantizer, though you can turn it off if you really want to.

+ *

+ * In 1-pass quantization the colormap must be chosen in advance of seeing the

+ * image.  We use a map consisting of all combinations of Ncolors[i] color

+ * values for the i'th component.  The Ncolors[] values are chosen so that

+ * their product, the total number of colors, is no more than that requested.

+ * (In most cases, the product will be somewhat less.)

+ *

+ * Since the colormap is orthogonal, the representative value for each color

+ * component can be determined without considering the other components;

+ * then these indexes can be combined into a colormap index by a standard

+ * N-dimensional-array-subscript calculation.  Most of the arithmetic involved

+ * can be precalculated and stored in the lookup table colorindex[].

+ * colorindex[i][j] maps pixel value j in component i to the nearest

+ * representative value (grid plane) for that component; this index is

+ * multiplied by the array stride for component i, so that the

+ * index of the colormap entry closest to a given pixel value is just

+ *    sum( colorindex[component-number][pixel-component-value] )

+ * Aside from being fast, this scheme allows for variable spacing between

+ * representative values with no additional lookup cost.

+ *

+ * If gamma correction has been applied in color conversion, it might be wise

+ * to adjust the color grid spacing so that the representative colors are

+ * equidistant in linear space.  At this writing, gamma correction is not

+ * implemented by jdcolor, so nothing is done here.

+ */

+

+

+/* Declarations for ordered dithering.

+ *

+ * We use a standard 16x16 ordered dither array.  The basic concept of ordered

+ * dithering is described in many references, for instance Dale Schumacher's

+ * chapter II.2 of Graphics Gems II (James Arvo, ed. Academic Press, 1991).

+ * In place of Schumacher's comparisons against a "threshold" value, we add a

+ * "dither" value to the input pixel and then round the result to the nearest

+ * output value.  The dither value is equivalent to (0.5 - threshold) times

+ * the distance between output values.  For ordered dithering, we assume that

+ * the output colors are equally spaced; if not, results will probably be

+ * worse, since the dither may be too much or too little at a given point.

+ *

+ * The normal calculation would be to form pixel value + dither, range-limit

+ * this to 0..MAXJSAMPLE, and then index into the colorindex table as usual.

+ * We can skip the separate range-limiting step by extending the colorindex

+ * table in both directions.

+ */

+

+#define ODITHER_SIZE  16	/* dimension of dither matrix */

+/* NB: if ODITHER_SIZE is not a power of 2, ODITHER_MASK uses will break */

+#define ODITHER_CELLS (ODITHER_SIZE*ODITHER_SIZE)	/* # cells in matrix */

+#define ODITHER_MASK  (ODITHER_SIZE-1) /* mask for wrapping around counters */

+

+typedef int ODITHER_MATRIX[ODITHER_SIZE][ODITHER_SIZE];

+typedef int (*ODITHER_MATRIX_PTR)[ODITHER_SIZE];

+

+static const UINT8 base_dither_matrix[ODITHER_SIZE][ODITHER_SIZE] = {

+  /* Bayer's order-4 dither array.  Generated by the code given in

+   * Stephen Hawley's article "Ordered Dithering" in Graphics Gems I.

+   * The values in this array must range from 0 to ODITHER_CELLS-1.

+   */

+  {   0,192, 48,240, 12,204, 60,252,  3,195, 51,243, 15,207, 63,255 },

+  { 128, 64,176,112,140, 76,188,124,131, 67,179,115,143, 79,191,127 },

+  {  32,224, 16,208, 44,236, 28,220, 35,227, 19,211, 47,239, 31,223 },

+  { 160, 96,144, 80,172,108,156, 92,163, 99,147, 83,175,111,159, 95 },

+  {   8,200, 56,248,  4,196, 52,244, 11,203, 59,251,  7,199, 55,247 },

+  { 136, 72,184,120,132, 68,180,116,139, 75,187,123,135, 71,183,119 },

+  {  40,232, 24,216, 36,228, 20,212, 43,235, 27,219, 39,231, 23,215 },

+  { 168,104,152, 88,164,100,148, 84,171,107,155, 91,167,103,151, 87 },

+  {   2,194, 50,242, 14,206, 62,254,  1,193, 49,241, 13,205, 61,253 },

+  { 130, 66,178,114,142, 78,190,126,129, 65,177,113,141, 77,189,125 },

+  {  34,226, 18,210, 46,238, 30,222, 33,225, 17,209, 45,237, 29,221 },

+  { 162, 98,146, 82,174,110,158, 94,161, 97,145, 81,173,109,157, 93 },

+  {  10,202, 58,250,  6,198, 54,246,  9,201, 57,249,  5,197, 53,245 },

+  { 138, 74,186,122,134, 70,182,118,137, 73,185,121,133, 69,181,117 },

+  {  42,234, 26,218, 38,230, 22,214, 41,233, 25,217, 37,229, 21,213 },

+  { 170,106,154, 90,166,102,150, 86,169,105,153, 89,165,101,149, 85 }

+};

+

+

+/* Declarations for Floyd-Steinberg dithering.

+ *

+ * Errors are accumulated into the array fserrors[], at a resolution of

+ * 1/16th of a pixel count.  The error at a given pixel is propagated

+ * to its not-yet-processed neighbors using the standard F-S fractions,

+ *		...	(here)	7/16

+ *		3/16	5/16	1/16

+ * We work left-to-right on even rows, right-to-left on odd rows.

+ *

+ * We can get away with a single array (holding one row's worth of errors)

+ * by using it to store the current row's errors at pixel columns not yet

+ * processed, but the next row's errors at columns already processed.  We

+ * need only a few extra variables to hold the errors immediately around the

+ * current column.  (If we are lucky, those variables are in registers, but

+ * even if not, they're probably cheaper to access than array elements are.)

+ *

+ * The fserrors[] array is indexed [component#][position].

+ * We provide (#columns + 2) entries per component; the extra entry at each

+ * end saves us from special-casing the first and last pixels.

+ *

+ * Note: on a wide image, we might not have enough room in a PC's near data

+ * segment to hold the error array; so it is allocated with alloc_large.

+ */

+

+#if BITS_IN_JSAMPLE == 8

+typedef INT16 FSERROR;		/* 16 bits should be enough */

+typedef int LOCFSERROR;		/* use 'int' for calculation temps */

+#else

+typedef INT32 FSERROR;		/* may need more than 16 bits */

+typedef INT32 LOCFSERROR;	/* be sure calculation temps are big enough */

+#endif

+

+typedef FSERROR FAR *FSERRPTR;	/* pointer to error array (in FAR storage!) */

+

+

+/* Private subobject */

+

+#define MAX_Q_COMPS 4		/* max components I can handle */

+

+typedef struct {

+  struct jpeg_color_quantizer pub; /* public fields */

+

+  /* Initially allocated colormap is saved here */

+  JSAMPARRAY sv_colormap;	/* The color map as a 2-D pixel array */

+  int sv_actual;		/* number of entries in use */

+

+  JSAMPARRAY colorindex;	/* Precomputed mapping for speed */

+  /* colorindex[i][j] = index of color closest to pixel value j in component i,

+   * premultiplied as described above.  Since colormap indexes must fit into

+   * JSAMPLEs, the entries of this array will too.

+   */

+  boolean is_padded;		/* is the colorindex padded for odither? */

+

+  int Ncolors[MAX_Q_COMPS];	/* # of values alloced to each component */

+

+  /* Variables for ordered dithering */

+  int row_index;		/* cur row's vertical index in dither matrix */

+  ODITHER_MATRIX_PTR odither[MAX_Q_COMPS]; /* one dither array per component */

+

+  /* Variables for Floyd-Steinberg dithering */

+  FSERRPTR fserrors[MAX_Q_COMPS]; /* accumulated errors */

+  boolean on_odd_row;		/* flag to remember which row we are on */

+} my_cquantizer;

+

+typedef my_cquantizer * my_cquantize_ptr;

+

+

+/*

+ * Policy-making subroutines for create_colormap and create_colorindex.

+ * These routines determine the colormap to be used.  The rest of the module

+ * only assumes that the colormap is orthogonal.

+ *

+ *  * select_ncolors decides how to divvy up the available colors

+ *    among the components.

+ *  * output_value defines the set of representative values for a component.

+ *  * largest_input_value defines the mapping from input values to

+ *    representative values for a component.

+ * Note that the latter two routines may impose different policies for

+ * different components, though this is not currently done.

+ */

+

+

+LOCAL(int)

+select_ncolors (j_decompress_ptr cinfo, int Ncolors[])

+/* Determine allocation of desired colors to components, */

+/* and fill in Ncolors[] array to indicate choice. */

+/* Return value is total number of colors (product of Ncolors[] values). */

+{

+  int nc = cinfo->out_color_components; /* number of color components */

+  int max_colors = cinfo->desired_number_of_colors;

+  int total_colors, iroot, i, j;

+  boolean changed;

+  long temp;

+  static const int RGB_order[3] = { RGB_GREEN, RGB_RED, RGB_BLUE };

+

+  /* We can allocate at least the nc'th root of max_colors per component. */

+  /* Compute floor(nc'th root of max_colors). */

+  iroot = 1;

+  do {

+    iroot++;

+    temp = iroot;		/* set temp = iroot ** nc */

+    for (i = 1; i < nc; i++)

+      temp *= iroot;

+  } while (temp <= (long) max_colors); /* repeat till iroot exceeds root */

+  iroot--;			/* now iroot = floor(root) */

+

+  /* Must have at least 2 color values per component */

+  if (iroot < 2)

+    ERREXIT1(cinfo, JERR_QUANT_FEW_COLORS, (int) temp);

+

+  /* Initialize to iroot color values for each component */

+  total_colors = 1;

+  for (i = 0; i < nc; i++) {

+    Ncolors[i] = iroot;

+    total_colors *= iroot;

+  }

+  /* We may be able to increment the count for one or more components without

+   * exceeding max_colors, though we know not all can be incremented.

+   * Sometimes, the first component can be incremented more than once!

+   * (Example: for 16 colors, we start at 2*2*2, go to 3*2*2, then 4*2*2.)

+   * In RGB colorspace, try to increment G first, then R, then B.

+   */

+  do {

+    changed = FALSE;

+    for (i = 0; i < nc; i++) {

+      j = (cinfo->out_color_space == JCS_RGB ? RGB_order[i] : i);

+      /* calculate new total_colors if Ncolors[j] is incremented */

+      temp = total_colors / Ncolors[j];

+      temp *= Ncolors[j]+1;	/* done in long arith to avoid oflo */

+      if (temp > (long) max_colors)

+	break;			/* won't fit, done with this pass */

+      Ncolors[j]++;		/* OK, apply the increment */

+      total_colors = (int) temp;

+      changed = TRUE;

+    }

+  } while (changed);

+

+  return total_colors;

+}

+

+

+LOCAL(int)

+output_value (j_decompress_ptr cinfo, int ci, int j, int maxj)

+/* Return j'th output value, where j will range from 0 to maxj */

+/* The output values must fall in 0..MAXJSAMPLE in increasing order */

+{

+  /* We always provide values 0 and MAXJSAMPLE for each component;

+   * any additional values are equally spaced between these limits.

+   * (Forcing the upper and lower values to the limits ensures that

+   * dithering can't produce a color outside the selected gamut.)

+   */

+  return (int) (((INT32) j * MAXJSAMPLE + maxj/2) / maxj);

+}

+

+

+LOCAL(int)

+largest_input_value (j_decompress_ptr cinfo, int ci, int j, int maxj)

+/* Return largest input value that should map to j'th output value */

+/* Must have largest(j=0) >= 0, and largest(j=maxj) >= MAXJSAMPLE */

+{

+  /* Breakpoints are halfway between values returned by output_value */

+  return (int) (((INT32) (2*j + 1) * MAXJSAMPLE + maxj) / (2*maxj));

+}

+

+

+/*

+ * Create the colormap.

+ */

+

+LOCAL(void)

+create_colormap (j_decompress_ptr cinfo)

+{

+  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;

+  JSAMPARRAY colormap;		/* Created colormap */

+  int total_colors;		/* Number of distinct output colors */

+  int i,j,k, nci, blksize, blkdist, ptr, val;

+

+  /* Select number of colors for each component */

+  total_colors = select_ncolors(cinfo, cquantize->Ncolors);

+

+  /* Report selected color counts */

+  if (cinfo->out_color_components == 3)

+    TRACEMS4(cinfo, 1, JTRC_QUANT_3_NCOLORS,

+	     total_colors, cquantize->Ncolors[0],

+	     cquantize->Ncolors[1], cquantize->Ncolors[2]);

+  else

+    TRACEMS1(cinfo, 1, JTRC_QUANT_NCOLORS, total_colors);

+

+  /* Allocate and fill in the colormap. */

+  /* The colors are ordered in the map in standard row-major order, */

+  /* i.e. rightmost (highest-indexed) color changes most rapidly. */

+

+  colormap = (*cinfo->mem->alloc_sarray)

+    ((j_common_ptr) cinfo, JPOOL_IMAGE,

+     (JDIMENSION) total_colors, (JDIMENSION) cinfo->out_color_components);

+

+  /* blksize is number of adjacent repeated entries for a component */

+  /* blkdist is distance between groups of identical entries for a component */

+  blkdist = total_colors;

+

+  for (i = 0; i < cinfo->out_color_components; i++) {

+    /* fill in colormap entries for i'th color component */

+    nci = cquantize->Ncolors[i]; /* # of distinct values for this color */

+    blksize = blkdist / nci;

+    for (j = 0; j < nci; j++) {

+      /* Compute j'th output value (out of nci) for component */

+      val = output_value(cinfo, i, j, nci-1);

+      /* Fill in all colormap entries that have this value of this component */

+      for (ptr = j * blksize; ptr < total_colors; ptr += blkdist) {

+	/* fill in blksize entries beginning at ptr */

+	for (k = 0; k < blksize; k++)

+	  colormap[i][ptr+k] = (JSAMPLE) val;

+      }

+    }

+    blkdist = blksize;		/* blksize of this color is blkdist of next */

+  }

+

+  /* Save the colormap in private storage,

+   * where it will survive color quantization mode changes.

+   */

+  cquantize->sv_colormap = colormap;

+  cquantize->sv_actual = total_colors;

+}

+

+

+/*

+ * Create the color index table.

+ */

+

+LOCAL(void)

+create_colorindex (j_decompress_ptr cinfo)

+{

+  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;

+  JSAMPROW indexptr;

+  int i,j,k, nci, blksize, val, pad;

+

+  /* For ordered dither, we pad the color index tables by MAXJSAMPLE in

+   * each direction (input index values can be -MAXJSAMPLE .. 2*MAXJSAMPLE).

+   * This is not necessary in the other dithering modes.  However, we

+   * flag whether it was done in case user changes dithering mode.

+   */

+  if (cinfo->dither_mode == JDITHER_ORDERED) {

+    pad = MAXJSAMPLE*2;

+    cquantize->is_padded = TRUE;

+  } else {

+    pad = 0;

+    cquantize->is_padded = FALSE;

+  }

+

+  cquantize->colorindex = (*cinfo->mem->alloc_sarray)

+    ((j_common_ptr) cinfo, JPOOL_IMAGE,

+     (JDIMENSION) (MAXJSAMPLE+1 + pad),

+     (JDIMENSION) cinfo->out_color_components);

+

+  /* blksize is number of adjacent repeated entries for a component */

+  blksize = cquantize->sv_actual;

+

+  for (i = 0; i < cinfo->out_color_components; i++) {

+    /* fill in colorindex entries for i'th color component */

+    nci = cquantize->Ncolors[i]; /* # of distinct values for this color */

+    blksize = blksize / nci;

+

+    /* adjust colorindex pointers to provide padding at negative indexes. */

+    if (pad)

+      cquantize->colorindex[i] += MAXJSAMPLE;

+

+    /* in loop, val = index of current output value, */

+    /* and k = largest j that maps to current val */

+    indexptr = cquantize->colorindex[i];

+    val = 0;

+    k = largest_input_value(cinfo, i, 0, nci-1);

+    for (j = 0; j <= MAXJSAMPLE; j++) {

+      while (j > k)		/* advance val if past boundary */

+	k = largest_input_value(cinfo, i, ++val, nci-1);

+      /* premultiply so that no multiplication needed in main processing */

+      indexptr[j] = (JSAMPLE) (val * blksize);

+    }

+    /* Pad at both ends if necessary */

+    if (pad)

+      for (j = 1; j <= MAXJSAMPLE; j++) {

+	indexptr[-j] = indexptr[0];

+	indexptr[MAXJSAMPLE+j] = indexptr[MAXJSAMPLE];

+      }

+  }

+}

+

+

+/*

+ * Create an ordered-dither array for a component having ncolors

+ * distinct output values.

+ */

+

+LOCAL(ODITHER_MATRIX_PTR)

+make_odither_array (j_decompress_ptr cinfo, int ncolors)

+{

+  ODITHER_MATRIX_PTR odither;

+  int j,k;

+  INT32 num,den;

+

+  odither = (ODITHER_MATRIX_PTR)

+    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

+				SIZEOF(ODITHER_MATRIX));

+  /* The inter-value distance for this color is MAXJSAMPLE/(ncolors-1).

+   * Hence the dither value for the matrix cell with fill order f

+   * (f=0..N-1) should be (N-1-2*f)/(2*N) * MAXJSAMPLE/(ncolors-1).

+   * On 16-bit-int machine, be careful to avoid overflow.

+   */

+  den = 2 * ODITHER_CELLS * ((INT32) (ncolors - 1));

+  for (j = 0; j < ODITHER_SIZE; j++) {

+    for (k = 0; k < ODITHER_SIZE; k++) {

+      num = ((INT32) (ODITHER_CELLS-1 - 2*((int)base_dither_matrix[j][k])))

+	    * MAXJSAMPLE;

+      /* Ensure round towards zero despite C's lack of consistency

+       * about rounding negative values in integer division...

+       */

+      odither[j][k] = (int) (num<0 ? -((-num)/den) : num/den);

+    }

+  }

+  return odither;

+}

+

+

+/*

+ * Create the ordered-dither tables.

+ * Components having the same number of representative colors may 

+ * share a dither table.

+ */

+

+LOCAL(void)

+create_odither_tables (j_decompress_ptr cinfo)

+{

+  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;

+  ODITHER_MATRIX_PTR odither;

+  int i, j, nci;

+

+  for (i = 0; i < cinfo->out_color_components; i++) {

+    nci = cquantize->Ncolors[i]; /* # of distinct values for this color */

+    odither = NULL;		/* search for matching prior component */

+    for (j = 0; j < i; j++) {

+      if (nci == cquantize->Ncolors[j]) {

+	odither = cquantize->odither[j];

+	break;

+      }

+    }

+    if (odither == NULL)	/* need a new table? */

+      odither = make_odither_array(cinfo, nci);

+    cquantize->odither[i] = odither;

+  }

+}

+

+

+/*

+ * Map some rows of pixels to the output colormapped representation.

+ */

+

+METHODDEF(void)

+color_quantize (j_decompress_ptr cinfo, JSAMPARRAY input_buf,

+		JSAMPARRAY output_buf, int num_rows)

+/* General case, no dithering */

+{

+  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;

+  JSAMPARRAY colorindex = cquantize->colorindex;

+  register int pixcode, ci;

+  register JSAMPROW ptrin, ptrout;

+  int row;

+  JDIMENSION col;

+  JDIMENSION width = cinfo->output_width;

+  register int nc = cinfo->out_color_components;

+

+  for (row = 0; row < num_rows; row++) {

+    ptrin = input_buf[row];

+    ptrout = output_buf[row];

+    for (col = width; col > 0; col--) {

+      pixcode = 0;

+      for (ci = 0; ci < nc; ci++) {

+	pixcode += GETJSAMPLE(colorindex[ci][GETJSAMPLE(*ptrin++)]);

+      }

+      *ptrout++ = (JSAMPLE) pixcode;

+    }

+  }

+}

+

+

+METHODDEF(void)

+color_quantize3 (j_decompress_ptr cinfo, JSAMPARRAY input_buf,

+		 JSAMPARRAY output_buf, int num_rows)

+/* Fast path for out_color_components==3, no dithering */

+{

+  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;

+  register int pixcode;

+  register JSAMPROW ptrin, ptrout;

+  JSAMPROW colorindex0 = cquantize->colorindex[0];

+  JSAMPROW colorindex1 = cquantize->colorindex[1];

+  JSAMPROW colorindex2 = cquantize->colorindex[2];

+  int row;

+  JDIMENSION col;

+  JDIMENSION width = cinfo->output_width;

+

+  for (row = 0; row < num_rows; row++) {

+    ptrin = input_buf[row];

+    ptrout = output_buf[row];

+    for (col = width; col > 0; col--) {

+      pixcode  = GETJSAMPLE(colorindex0[GETJSAMPLE(*ptrin++)]);

+      pixcode += GETJSAMPLE(colorindex1[GETJSAMPLE(*ptrin++)]);

+      pixcode += GETJSAMPLE(colorindex2[GETJSAMPLE(*ptrin++)]);

+      *ptrout++ = (JSAMPLE) pixcode;

+    }

+  }

+}

+

+

+METHODDEF(void)

+quantize_ord_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf,

+		     JSAMPARRAY output_buf, int num_rows)

+/* General case, with ordered dithering */

+{

+  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;

+  register JSAMPROW input_ptr;

+  register JSAMPROW output_ptr;

+  JSAMPROW colorindex_ci;

+  int * dither;			/* points to active row of dither matrix */

+  int row_index, col_index;	/* current indexes into dither matrix */

+  int nc = cinfo->out_color_components;

+  int ci;

+  int row;

+  JDIMENSION col;

+  JDIMENSION width = cinfo->output_width;

+

+  for (row = 0; row < num_rows; row++) {

+    /* Initialize output values to 0 so can process components separately */

+    FMEMZERO((void FAR *) output_buf[row],

+	     (size_t) (width * SIZEOF(JSAMPLE)));

+    row_index = cquantize->row_index;

+    for (ci = 0; ci < nc; ci++) {

+      input_ptr = input_buf[row] + ci;

+      output_ptr = output_buf[row];

+      colorindex_ci = cquantize->colorindex[ci];

+      dither = cquantize->odither[ci][row_index];

+      col_index = 0;

+

+      for (col = width; col > 0; col--) {

+	/* Form pixel value + dither, range-limit to 0..MAXJSAMPLE,

+	 * select output value, accumulate into output code for this pixel.

+	 * Range-limiting need not be done explicitly, as we have extended

+	 * the colorindex table to produce the right answers for out-of-range

+	 * inputs.  The maximum dither is +- MAXJSAMPLE; this sets the

+	 * required amount of padding.

+	 */

+	*output_ptr += colorindex_ci[GETJSAMPLE(*input_ptr)+dither[col_index]];

+	input_ptr += nc;

+	output_ptr++;

+	col_index = (col_index + 1) & ODITHER_MASK;

+      }

+    }

+    /* Advance row index for next row */

+    row_index = (row_index + 1) & ODITHER_MASK;

+    cquantize->row_index = row_index;

+  }

+}

+

+

+METHODDEF(void)

+quantize3_ord_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf,

+		      JSAMPARRAY output_buf, int num_rows)

+/* Fast path for out_color_components==3, with ordered dithering */

+{

+  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;

+  register int pixcode;

+  register JSAMPROW input_ptr;

+  register JSAMPROW output_ptr;

+  JSAMPROW colorindex0 = cquantize->colorindex[0];

+  JSAMPROW colorindex1 = cquantize->colorindex[1];

+  JSAMPROW colorindex2 = cquantize->colorindex[2];

+  int * dither0;		/* points to active row of dither matrix */

+  int * dither1;

+  int * dither2;

+  int row_index, col_index;	/* current indexes into dither matrix */

+  int row;

+  JDIMENSION col;

+  JDIMENSION width = cinfo->output_width;

+

+  for (row = 0; row < num_rows; row++) {

+    row_index = cquantize->row_index;

+    input_ptr = input_buf[row];

+    output_ptr = output_buf[row];

+    dither0 = cquantize->odither[0][row_index];

+    dither1 = cquantize->odither[1][row_index];

+    dither2 = cquantize->odither[2][row_index];

+    col_index = 0;

+

+    for (col = width; col > 0; col--) {

+      pixcode  = GETJSAMPLE(colorindex0[GETJSAMPLE(*input_ptr++) +

+					dither0[col_index]]);

+      pixcode += GETJSAMPLE(colorindex1[GETJSAMPLE(*input_ptr++) +

+					dither1[col_index]]);

+      pixcode += GETJSAMPLE(colorindex2[GETJSAMPLE(*input_ptr++) +

+					dither2[col_index]]);

+      *output_ptr++ = (JSAMPLE) pixcode;

+      col_index = (col_index + 1) & ODITHER_MASK;

+    }

+    row_index = (row_index + 1) & ODITHER_MASK;

+    cquantize->row_index = row_index;

+  }

+}

+

+

+METHODDEF(void)

+quantize_fs_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf,

+		    JSAMPARRAY output_buf, int num_rows)

+/* General case, with Floyd-Steinberg dithering */

+{

+  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;

+  register LOCFSERROR cur;	/* current error or pixel value */

+  LOCFSERROR belowerr;		/* error for pixel below cur */

+  LOCFSERROR bpreverr;		/* error for below/prev col */

+  LOCFSERROR bnexterr;		/* error for below/next col */

+  LOCFSERROR delta;

+  register FSERRPTR errorptr;	/* => fserrors[] at column before current */

+  register JSAMPROW input_ptr;

+  register JSAMPROW output_ptr;

+  JSAMPROW colorindex_ci;

+  JSAMPROW colormap_ci;

+  int pixcode;

+  int nc = cinfo->out_color_components;

+  int dir;			/* 1 for left-to-right, -1 for right-to-left */

+  int dirnc;			/* dir * nc */

+  int ci;

+  int row;

+  JDIMENSION col;

+  JDIMENSION width = cinfo->output_width;

+  JSAMPLE *range_limit = cinfo->sample_range_limit;

+  SHIFT_TEMPS

+

+  for (row = 0; row < num_rows; row++) {

+    /* Initialize output values to 0 so can process components separately */

+    FMEMZERO((void FAR *) output_buf[row],

+	     (size_t) (width * SIZEOF(JSAMPLE)));

+    for (ci = 0; ci < nc; ci++) {

+      input_ptr = input_buf[row] + ci;

+      output_ptr = output_buf[row];

+      if (cquantize->on_odd_row) {

+	/* work right to left in this row */

+	input_ptr += (width-1) * nc; /* so point to rightmost pixel */

+	output_ptr += width-1;

+	dir = -1;

+	dirnc = -nc;

+	errorptr = cquantize->fserrors[ci] + (width+1); /* => entry after last column */

+      } else {

+	/* work left to right in this row */

+	dir = 1;

+	dirnc = nc;

+	errorptr = cquantize->fserrors[ci]; /* => entry before first column */

+      }

+      colorindex_ci = cquantize->colorindex[ci];

+      colormap_ci = cquantize->sv_colormap[ci];

+      /* Preset error values: no error propagated to first pixel from left */

+      cur = 0;

+      /* and no error propagated to row below yet */

+      belowerr = bpreverr = 0;

+

+      for (col = width; col > 0; col--) {

+	/* cur holds the error propagated from the previous pixel on the

+	 * current line.  Add the error propagated from the previous line

+	 * to form the complete error correction term for this pixel, and

+	 * round the error term (which is expressed * 16) to an integer.

+	 * RIGHT_SHIFT rounds towards minus infinity, so adding 8 is correct

+	 * for either sign of the error value.

+	 * Note: errorptr points to *previous* column's array entry.

+	 */

+	cur = RIGHT_SHIFT(cur + errorptr[dir] + 8, 4);

+	/* Form pixel value + error, and range-limit to 0..MAXJSAMPLE.

+	 * The maximum error is +- MAXJSAMPLE; this sets the required size

+	 * of the range_limit array.

+	 */

+	cur += GETJSAMPLE(*input_ptr);

+	cur = GETJSAMPLE(range_limit[cur]);

+	/* Select output value, accumulate into output code for this pixel */

+	pixcode = GETJSAMPLE(colorindex_ci[cur]);

+	*output_ptr += (JSAMPLE) pixcode;

+	/* Compute actual representation error at this pixel */

+	/* Note: we can do this even though we don't have the final */

+	/* pixel code, because the colormap is orthogonal. */

+	cur -= GETJSAMPLE(colormap_ci[pixcode]);

+	/* Compute error fractions to be propagated to adjacent pixels.

+	 * Add these into the running sums, and simultaneously shift the

+	 * next-line error sums left by 1 column.

+	 */

+	bnexterr = cur;

+	delta = cur * 2;

+	cur += delta;		/* form error * 3 */

+	errorptr[0] = (FSERROR) (bpreverr + cur);

+	cur += delta;		/* form error * 5 */

+	bpreverr = belowerr + cur;

+	belowerr = bnexterr;

+	cur += delta;		/* form error * 7 */

+	/* At this point cur contains the 7/16 error value to be propagated

+	 * to the next pixel on the current line, and all the errors for the

+	 * next line have been shifted over. We are therefore ready to move on.

+	 */

+	input_ptr += dirnc;	/* advance input ptr to next column */

+	output_ptr += dir;	/* advance output ptr to next column */

+	errorptr += dir;	/* advance errorptr to current column */

+      }

+      /* Post-loop cleanup: we must unload the final error value into the

+       * final fserrors[] entry.  Note we need not unload belowerr because

+       * it is for the dummy column before or after the actual array.

+       */

+      errorptr[0] = (FSERROR) bpreverr; /* unload prev err into array */

+    }

+    cquantize->on_odd_row = (cquantize->on_odd_row ? FALSE : TRUE);

+  }

+}

+

+

+/*

+ * Allocate workspace for Floyd-Steinberg errors.

+ */

+

+LOCAL(void)

+alloc_fs_workspace (j_decompress_ptr cinfo)

+{

+  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;

+  size_t arraysize;

+  int i;

+

+  arraysize = (size_t) ((cinfo->output_width + 2) * SIZEOF(FSERROR));

+  for (i = 0; i < cinfo->out_color_components; i++) {

+    cquantize->fserrors[i] = (FSERRPTR)

+      (*cinfo->mem->alloc_large)((j_common_ptr) cinfo, JPOOL_IMAGE, arraysize);

+  }

+}

+

+

+/*

+ * Initialize for one-pass color quantization.

+ */

+

+METHODDEF(void)

+start_pass_1_quant (j_decompress_ptr cinfo, boolean is_pre_scan)

+{

+  my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;

+  size_t arraysize;

+  int i;

+

+  /* Install my colormap. */

+  cinfo->colormap = cquantize->sv_colormap;

+  cinfo->actual_number_of_colors = cquantize->sv_actual;

+

+  /* Initialize for desired dithering mode. */

+  switch (cinfo->dither_mode) {

+  case JDITHER_NONE:

+    if (cinfo->out_color_components == 3)

+      cquantize->pub.color_quantize = color_quantize3;

+    else

+      cquantize->pub.color_quantize = color_quantize;

+    break;

+  case JDITHER_ORDERED:

+    if (cinfo->out_color_components == 3)

+      cquantize->pub.color_quantize = quantize3_ord_dither;

+    else

+      cquantize->pub.color_quantize = quantize_ord_dither;

+    cquantize->row_index = 0;	/* initialize state for ordered dither */

+    /* If user changed to ordered dither from another mode,

+     * we must recreate the color index table with padding.

+     * This will cost extra space, but probably isn't very likely.

+     */

+    if (! cquantize->is_padded)

+      create_colorindex(cinfo);

+    /* Create ordered-dither tables if we didn't already. */

+    if (cquantize->odither[0] == NULL)

+      create_odither_tables(cinfo);

+    break;

+  case JDITHER_FS:

+    cquantize->pub.color_quantize = quantize_fs_dither;

+    cquantize->on_odd_row = FALSE; /* initialize state for F-S dither */

+    /* Allocate Floyd-Steinberg workspace if didn't already. */

+    if (cquantize->fserrors[0] == NULL)

+      alloc_fs_workspace(cinfo);

+    /* Initialize the propagated errors to zero. */

+    arraysize = (size_t) ((cinfo->output_width + 2) * SIZEOF(FSERROR));

+    for (i = 0; i < cinfo->out_color_components; i++)

+      FMEMZERO((void FAR *) cquantize->fserrors[i], arraysize);

+    break;

+  default:

+    ERREXIT(cinfo, JERR_NOT_COMPILED);

+    break;

+  }

+}

+

+

+/*

+ * Finish up at the end of the pass.

+ */

+

+METHODDEF(void)

+finish_pass_1_quant (j_decompress_ptr cinfo)

+{

+  /* no work in 1-pass case */

+}

+

+

+/*

+ * Switch to a new external colormap between output passes.

+ * Shouldn't get to this module!

+ */

+

+METHODDEF(void)

+new_color_map_1_quant (j_decompress_ptr cinfo)

+{

+  ERREXIT(cinfo, JERR_MODE_CHANGE);

+}

+

+

+/*

+ * Module initialization routine for 1-pass color quantization.

+ */

+

+GLOBAL(void)

+jinit_1pass_quantizer (j_decompress_ptr cinfo)

+{

+  my_cquantize_ptr cquantize;

+

+  cquantize = (my_cquantize_ptr)

+    (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,

+				SIZEOF(my_cquantizer));

+  cinfo->cquantize = (struct jpeg_color_quantizer *) cquantize;

+  cquantize->pub.start_pass = start_pass_1_quant;

+  cquantize->pub.finish_pass = finish_pass_1_quant;

+  cquantize->pub.new_color_map = new_color_map_1_quant;

+  cquantize->fserrors[0] = NULL; /* Flag FS workspace not allocated */

+  cquantize->odither[0] = NULL;	/* Also flag odither arrays not allocated */

+

+  /* Make sure my internal arrays won't overflow */

+  if (cinfo->out_color_components > MAX_Q_COMPS)

+    ERREXIT1(cinfo, JERR_QUANT_COMPONENTS, MAX_Q_COMPS);

+  /* Make sure colormap indexes can be represented by JSAMPLEs */

+  if (cinfo->desired_number_of_colors > (MAXJSAMPLE+1))

+    ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, MAXJSAMPLE+1);

+

+  /* Create the colormap and color index table. */

+  create_colormap(cinfo);

+  create_colorindex(cinfo);

+

+  /* Allocate Floyd-Steinberg workspace now if requested.

+   * We do this now since it is FAR storage and may affect the memory

+   * manager's space calculations.  If the user changes to FS dither

+   * mode in a later pass, we will allocate the space then, and will

+   * possibly overrun the max_memory_to_use setting.

+   */

+  if (cinfo->dither_mode == JDITHER_FS)

+    alloc_fs_workspace(cinfo);

+}

+

+#endif /* QUANT_1PASS_SUPPORTED */