int main(int argc, char *const argv[])
{
char *map_output_file = NULL;
if (argc < 3) {
usage(argv[0]);
return 1;
}
opterr = 0;
int c;
while((c = getopt(argc, argv, "ho:")) != -1) {
switch (c) {
case 'h':
usage(argv[0]);
return 0;
case 'o':
map_output_file = optarg;
break;
default:
fprintf(stderr, "Unknown option\n");
return 1;
}
}
if (optind+1 >= argc) {
fprintf(stderr, "You must specify at least 2 files to compare\n");
return 1;
}
const char *file1 = argv[optind];
png24_image image1 = {};
int retval = read_image(file1, &image1);
if (retval) {
fprintf(stderr, "Can't read %s\n", file1);
return retval;
}
dssim_image *original = dssim_create_image(image1.row_pointers, DSSIM_RGBA, image1.width, image1.height, image1.gamma);
free(image1.row_pointers);
free(image1.rgba_data);
for (int arg = optind+1; arg < argc; arg++) {
const char *file2 = argv[arg];
png24_image image2 = {};
retval = read_image(file2, &image2);
if (retval) {
fprintf(stderr, "Can't read %s\n", file2);
break;
}
if (image1.width != image2.width || image1.height != image2.height) {
fprintf(stderr, "Image %s has different size than %s\n", file2, file1);
break;
}
dssim_image *modified = dssim_create_image(image2.row_pointers, DSSIM_RGBA, image2.width, image2.height, image2.gamma);
free(image2.row_pointers);
free(image2.rgba_data);
float *map = NULL;
double dssim = dssim_compare(original, modified, map_output_file ? &map : NULL);
dssim_dealloc_image(modified);
printf("%.6f\t%s\n", dssim, file2);
if (map) {
dssim_rgba *out = (dssim_rgba*)map;
for(int i=0; i < image2.width*image2.height; i++) {
const float max = 1.0 - map[i];
const float maxsq = max * max;
out[i] = (dssim_rgba) {
.r = to_byte(max * 3.0),
.g = to_byte(maxsq * 3.0),
.b = to_byte((max-0.5) * 2.0f),
.a = 255,
};
}
if (write_image(map_output_file, out, image2.width, image2.height)) {
fprintf(stderr, "Can't write %s\n", map_output_file);
free(map);
return 1;
}
free(map);
}
}
dssim_dealloc_image(original);
return retval;
}
/*
* given a source image, a destination filepath and a set of image metadata thresholds,
* search for the lowest-quality version of the source image whose properties fall within our
* thresholds.
* this will produce an image file that looks the same to the casual observer, but which
* contains much less information and results in a smaller file.
* typical savings on unoptimized images vary widely from 10-80%, with 25-50% being most common.
*/
MagickWand * search_quality(MagickWand *mw, const char *dst,
const struct imgmin_options *opt)
{
MagickWand *tmp = NULL;
char tmpfile[MAX_PATH] = "/tmp/imgminXXXXXX";
if (0 == strcmp("-", dst))
{
if (-1 == mkstemp(tmpfile))
{
perror("mkstemp");
return CloneMagickWand(mw);
}
} else {
strcpy(tmpfile, dst);
}
/*
* The overwhelming majority of JPEGs are TrueColorType; it is those types, with a low
* unique color count, that we must avoid.
*/
if (!enough_colors(mw, opt))
{
fprintf(stdout, " Color count is too low, skipping...\n");
return CloneMagickWand(mw);
}
if (quality(mw) < opt->quality_in_min)
{
fprintf(stdout, " Quality < %u, won't second-guess...\n", opt->quality_in_min);
return CloneMagickWand(mw);
}
size_t width = MagickGetImageWidth(mw);
size_t height = MagickGetImageHeight(mw);
dssim_info *dssim = dssim_init(1);
void *convert_data = convert_row_start(mw);
dssim_set_original_float_callback(dssim, width, height, convert_row_callback, convert_data);
convert_row_finish(convert_data);
{
ExceptionInfo *exception = AcquireExceptionInfo();
const double original_density = color_density(mw);
unsigned qmax = min(quality(mw), opt->quality_out_max);
unsigned qmin = opt->quality_out_min;
unsigned steps = 0;
/*
* binary search of quality space for optimally lowest quality that
* produces an acceptable level of distortion
*/
while (qmax > qmin + 1 && steps < opt->max_steps)
{
double density_ratio;
unsigned q;
steps++;
q = (qmax + qmin) / 2;
/* change quality */
tmp = CloneMagickWand(mw);
MagickSetImageCompressionQuality(tmp, q);
/* apply quality change */
MagickWriteImages(tmp, tmpfile, MagickTrue);
DestroyMagickWand(tmp);
tmp = NewMagickWand();
MagickReadImage(tmp, tmpfile);
void *convert_data = convert_row_start(tmp);
dssim_set_modified_float_callback(dssim, width, height, convert_row_callback, convert_data);
convert_row_finish(convert_data);
double error = 20.0 * dssim_compare(dssim, NULL); // scaled to threshold of previous implementation
density_ratio = fabs(color_density(tmp) - original_density) / original_density;
/* color density ratio threshold is an alternative quality measure.
If it's exceeded, pretend MSE was higher to increase quality */
if (density_ratio > opt->color_density_ratio) {
error *= 1.25 + density_ratio; // fudge factor
}
/* eliminate half search space based on whether distortion within thresholds */
if (error > opt->error_threshold)
{
qmin = q;
} else {
qmax = q;
}
if (opt->show_progress)
{
fprintf(stdout, "%.2f/%.2f@%u ", error, density_ratio, q);
}
/* Stop searching if close enough to the target */
if (fabs(error - opt->error_threshold) < opt->error_threshold * ERROR_THRESHOLD_INACCURACY) {
qmax = q;
break;
}
}
if (opt->show_progress)
{
putc('\n', stdout);
}
MagickSetImageCompressionQuality(mw, qmax);
/* "Chroma sub-sampling works because human vision is relatively insensitive to
* small areas of colour. It gives a significant reduction in file sizes, with
* little loss of perceived quality." [3]
*/
#if MagickLibVersion >= 0x630 /* FIXME: available in 0x660, not available in 0x628, not sure which version it was introduced in */
(void) MagickSetImageProperty(mw, "jpeg:sampling-factor", "2x2");
#endif
/* strip an image of all profiles and comments */
(void) MagickStripImage(mw);
MagickWriteImages(mw, tmpfile, MagickTrue);
(void) DestroyMagickWand(tmp);
tmp = NewMagickWand();
MagickReadImage(tmp, tmpfile);
exception = DestroyExceptionInfo(exception);
}
return tmp;
}
int main(int argc, char *const argv[])
{
char *map_output_file = NULL;
if (argc < 3) {
usage(argv[0]);
return 1;
}
opterr = 0;
int c;
while((c = getopt(argc, argv, "ho:")) != -1) {
switch (c) {
case 'h':
usage(argv[0]);
return 0;
case 'o':
map_output_file = optarg;
break;
default:
fprintf(stderr, "Unknown option\n");
return 1;
}
}
if (optind+1 >= argc) {
fprintf(stderr, "You must specify at least 2 files to compare\n");
return 1;
}
const char *file1 = argv[optind];
png24_image image1 = {};
int retval = read_image(file1, &image1);
if (retval) {
fprintf(stderr, "Can't read %s (%d)\n", file1, retval);
return retval;
}
dssim_attr *attr = dssim_create_attr();
dssim_image *original = dssim_create_image(attr, image1.row_pointers, DSSIM_RGBA, image1.width, image1.height, get_gamma(&image1));
free(image1.row_pointers);
free(image1.rgba_data);
for (int arg = optind+1; arg < argc; arg++) {
const char *file2 = argv[arg];
png24_image image2 = {};
retval = read_image(file2, &image2);
if (retval) {
fprintf(stderr, "Can't read %s (%d)\n", file2, retval);
break;
}
if (image1.width != image2.width || image1.height != image2.height) {
fprintf(stderr, "Image %s has different size than %s\n", file2, file1);
retval = 4;
break;
}
dssim_image *modified = dssim_create_image(attr, image2.row_pointers, DSSIM_RGBA, image2.width, image2.height, get_gamma(&image2));
free(image2.row_pointers);
free(image2.rgba_data);
if (!modified) {
fprintf(stderr, "Unable to process image %s\n", file2);
retval = 4;
break;
}
if (map_output_file) {
dssim_set_save_ssim_maps(attr, 1, 1);
}
double dssim = dssim_compare(attr, original, modified);
dssim_dealloc_image(modified);
printf("%.8f\t%s\n", dssim, file2);
if (map_output_file) {
dssim_ssim_map map_meta = dssim_pop_ssim_map(attr, 0, 0);
dssim_px_t *map = map_meta.data;
dssim_rgba *out = (dssim_rgba*)map;
for(int i=0; i < map_meta.width*map_meta.height; i++) {
const dssim_px_t max = 1.0 - map[i];
const dssim_px_t maxsq = max * max;
out[i] = (dssim_rgba) {
.r = to_byte(max * 3.0),
.g = to_byte(maxsq * 6.0),
.b = to_byte(max / ((1.0 - map_meta.dssim) * 4.0)),
.a = 255,
};
}
if (write_image(map_output_file, out, map_meta.width, map_meta.height)) {
fprintf(stderr, "Can't write %s\n", map_output_file);
free(map);
return 1;
}
free(map);
}
}
dssim_dealloc_image(original);
dssim_dealloc_attr(attr);
return retval;
}
