hist *histogram(read_info *input_image, int reqcolors, int speed_tradeoff)
{
hist *hist;
int ignorebits=0;
const rgb_pixel *const *input_pixels = (const rgb_pixel *const *)input_image->row_pointers;
int cols = input_image->width, rows = input_image->height;
double gamma = input_image->gamma;
assert(gamma > 0);
/*
** Step 2: attempt to make a histogram of the colors, unclustered.
** If at first we don't succeed, increase ignorebits to increase color
** coherence and try again.
*/
if (speed_tradeoff > 7) ignorebits++;
int maxcolors = (1<<17) + (1<<18)*(10-speed_tradeoff);
verbose_printf(" making histogram...");
for (; ;) {
hist = pam_computeacolorhist(input_pixels, cols, rows, gamma, maxcolors, ignorebits, speed_tradeoff < 9);
if (hist) break;
ignorebits++;
verbose_printf("too many colors!\n scaling colors to improve clustering...");
}
verbose_printf("%d colors found\n", hist->size);
return hist;
}
int msQuantizeRasterBuffer(rgbaPixel *pixelsIn,int height,int width,
unsigned int *reqcolors, rgbaPixel *palette,
unsigned int *palette_scaling_maxval)
{
register rgbaPixel *pP;
register int col;
unsigned char newmaxval;
acolorhist_vector achv, acolormap=NULL;
int row;
int colors;
int newcolors = 0;
int x;
*palette_scaling_maxval = 255;
int row_step = width*4;
rgbaPixel **apixels=(rgbaPixel**)malloc(height*sizeof(rgbaPixel**));
for(row=0;row<height;row++) {
apixels[row]=(rgbaPixel*)(&(pixelsIn[row*width]));
}
/*
** Step 2: attempt to make a histogram of the colors, unclustered.
** If at first we don't succeed, lower maxval to increase color
** coherence and try again. This will eventually terminate, with
** maxval at worst 15, since 32^3 is approximately MAXCOLORS.
[GRR POSSIBLE BUG: what about 32^4 ?]
*/
for ( ; ; ) {
achv = pam_computeacolorhist(
apixels, width, height, MAXCOLORS, &colors );
if ( achv != (acolorhist_vector) 0 )
break;
newmaxval = *palette_scaling_maxval / 2;
for ( row = 0; row < height; ++row )
for ( col = 0, pP = apixels[row]; col < width; ++col, ++pP )
PAM_DEPTH( *pP, *pP, *palette_scaling_maxval, newmaxval );
*palette_scaling_maxval = newmaxval;
}
newcolors = MS_MIN(colors, *reqcolors);
acolormap = mediancut(achv, colors, width*height, *palette_scaling_maxval, newcolors);
pam_freeacolorhist(achv);
*reqcolors = newcolors;
for (x = 0; x < newcolors; ++x) {
palette[x].r = acolormap[x].acolor.r;
palette[x].g = acolormap[x].acolor.g;
palette[x].b = acolormap[x].acolor.b;
palette[x].a = acolormap[x].acolor.a;
}
free(acolormap);
free(apixels);
return MS_SUCCESS;
}
/**
* Compute a palette for the given RGBA rasterBuffer using a median cut quantization.
* - rb: the rasterBuffer to quantize
* - reqcolors: the desired number of colors the palette should contain. will be set
* with the actual number of entries in the computed palette
* - forced_palette: entries that should appear in the computed palette
* - num_forced_palette_entries: number of entries contained in "force_palette". if 0,
* "force_palette" can be NULL
* - palette_scaling_maxval: the quantization process may have to reduce the image depth
* by iteratively dividing the pixels by 2. In case palette_scaling_maxval is set to
* something different than 255, the returned palette colors have to be scaled back up to
* 255, and rb's pixels will have been scaled down to maxsize (see bug #3848)
*/
int msQuantizeRasterBuffer(rasterBufferObj *rb,
unsigned int *reqcolors, rgbaPixel *palette,
rgbaPixel *forced_palette, int num_forced_palette_entries,
unsigned int *palette_scaling_maxval)
{
rgbaPixel **apixels=NULL; /* pointer to the start rows of truecolor pixels */
register rgbaPixel *pP;
register int col;
unsigned char newmaxval;
acolorhist_vector achv, acolormap=NULL;
int row;
int colors;
int newcolors = 0;
int x;
/* int channels; */
assert(rb->type == MS_BUFFER_BYTE_RGBA);
*palette_scaling_maxval = 255;
apixels=(rgbaPixel**)msSmallMalloc(rb->height*sizeof(rgbaPixel*));
for(row=0; row<rb->height; row++) {
apixels[row]=(rgbaPixel*)(&(rb->data.rgba.pixels[row * rb->data.rgba.row_step]));
}
/*
** Step 2: attempt to make a histogram of the colors, unclustered.
** If at first we don't succeed, lower maxval to increase color
** coherence and try again. This will eventually terminate, with
** maxval at worst 15, since 32^3 is approximately MAXCOLORS.
[GRR POSSIBLE BUG: what about 32^4 ?]
*/
for ( ; ; ) {
achv = pam_computeacolorhist(
apixels, rb->width, rb->height, MAXCOLORS, &colors );
if ( achv != (acolorhist_vector) 0 )
break;
newmaxval = *palette_scaling_maxval / 2;
for ( row = 0; row < rb->height; ++row )
for ( col = 0, pP = apixels[row]; col < rb->width; ++col, ++pP )
PAM_DEPTH( *pP, *pP, *palette_scaling_maxval, newmaxval );
*palette_scaling_maxval = newmaxval;
}
newcolors = MS_MIN(colors, *reqcolors);
acolormap = mediancut(achv, colors, rb->width*rb->height, *palette_scaling_maxval, newcolors);
pam_freeacolorhist(achv);
*reqcolors = newcolors;
for (x = 0; x < newcolors; ++x) {
palette[x].r = acolormap[x].acolor.r;
palette[x].g = acolormap[x].acolor.g;
palette[x].b = acolormap[x].acolor.b;
palette[x].a = acolormap[x].acolor.a;
}
free(acolormap);
free(apixels);
return MS_SUCCESS;
}
/**
* Compute a palette for the given RGBA rasterBuffer using a median cut quantization.
* - rb: the rasterBuffer to quantize
* - reqcolors: the desired number of colors the palette should contain. will be set
* with the actual number of entries in the computed palette
* - palette: preallocated array of palette entries that will be populated by the
* function
* - maxval: max value of pixel intensity. In some cases, the input data has to
* be rescaled to compute the quantization. if the returned value of maxscale is
* less than 255, this means that the input pixels have been rescaled, and that
* the returned palette must be upscaled before being written to the png file
* - forced_palette: entries that should appear in the computed palette
* - num_forced_palette_entries: number of entries contained in "force_palette". if 0,
* "force_palette" can be NULL
*/
int _mapcache_imageio_quantize_image(mapcache_image *rb,
unsigned int *reqcolors, rgbaPixel *palette,
unsigned int *maxval,
rgbaPixel *forced_palette, int num_forced_palette_entries) {
rgbaPixel **apixels=NULL; /* pointer to the start rows of truecolor pixels */
register rgbaPixel *pP;
register int col;
unsigned char newmaxval;
acolorhist_vector achv, acolormap=NULL;
int row;
int colors;
int newcolors = 0;
int x;
/* int channels; */
*maxval = 255;
apixels=(rgbaPixel**)malloc(rb->h*sizeof(rgbaPixel**));
if(!apixels) return MAPCACHE_FAILURE;
for(row=0;row<rb->h;row++) {
apixels[row]=(rgbaPixel*)(&(rb->data[row * rb->stride]));
}
/*
** Step 2: attempt to make a histogram of the colors, unclustered.
** If at first we don't succeed, lower maxval to increase color
** coherence and try again. This will eventually terminate, with
** maxval at worst 15, since 32^3 is approximately MAXCOLORS.
[GRR POSSIBLE BUG: what about 32^4 ?]
*/
for ( ; ; ) {
achv = pam_computeacolorhist(
apixels, rb->w, rb->h, MAXCOLORS, &colors );
if ( achv != (acolorhist_vector) 0 )
break;
newmaxval = *maxval / 2;
for ( row = 0; row < rb->h; ++row )
for ( col = 0, pP = apixels[row]; col < rb->w; ++col, ++pP )
PAM_DEPTH( *pP, *pP, *maxval, newmaxval );
*maxval = newmaxval;
}
newcolors = MAPCACHE_MIN(colors, *reqcolors);
acolormap = mediancut(achv, colors, rb->w*rb->h, *maxval, newcolors);
pam_freeacolorhist(achv);
*reqcolors = newcolors;
for (x = 0; x < newcolors; ++x) {
palette[x].r = acolormap[x].acolor.r;
palette[x].g = acolormap[x].acolor.g;
palette[x].b = acolormap[x].acolor.b;
palette[x].a = acolormap[x].acolor.a;
}
free(acolormap);
free(apixels);
return MAPCACHE_SUCCESS;
}
