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