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raze/libraries/jpeg/jquant1.c
Christoph Oelckers 718112a8fe - added external libraries for music format playback and decompression from GZDoom. 
Currently none of these is being used, but eventually they will, once more code gets ported over.
So it's better to have them right away and avoid editing the project file too much, only to revert that later.
2019-09-22 08:59:48 +02:00

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/*
* 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 */
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