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dwebp: add PAM output support

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retains the alpha channel rather than stripping it as with PPM.

display from ImageMagick can render the files

Change-Id: I4f3a5d332937e0aeaf4e3fbd214fdae3b5382fb8
This commit is contained in:
James Zern
2012-07-20 16:06:06 -07:00
parent c3a207b9f4
commit d919ed06eb
2 changed files with 27 additions and 8 deletions
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26
examples/dwebp.c
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@ -59,6 +59,7 @@ extern void* VP8GetCPUInfo; // opaque forward declaration.
// Output types
typedef enum {
PNG = 0,
PAM,
PPM,
PGM,
ALPHA_PLANE_ONLY // this is for experimenting only
@ -201,15 +202,22 @@ static int WritePNG(FILE* out_file, const WebPDecBuffer* const buffer) {
}
#endif
static int WritePPM(FILE* fout, const WebPDecBuffer* const buffer) {
static int WritePPM(FILE* fout, const WebPDecBuffer* const buffer, int alpha) {
const uint32_t width = buffer->width;
const uint32_t height = buffer->height;
const unsigned char* const rgb = buffer->u.RGBA.rgba;
const int stride = buffer->u.RGBA.stride;
const size_t bytes_per_px = alpha ? 4 : 3;
uint32_t y;
fprintf(fout, "P6\n%d %d\n255\n", width, height);
if (alpha) {
fprintf(fout, "P7\nWIDTH %d\nHEIGHT %d\nDEPTH 4\nMAXVAL 255\n"
"TUPLTYPE RGB_ALPHA\nENDHDR\n", width, height);
} else {
fprintf(fout, "P6\n%d %d\n255\n", width, height);
}
for (y = 0; y < height; ++y) {
if (fwrite(rgb + y * stride, width, 3, fout) != 3) {
if (fwrite(rgb + y * stride, width, bytes_per_px, fout) != bytes_per_px) {
return 0;
}
}
@ -289,8 +297,10 @@ static void SaveOutput(const WebPDecBuffer* const buffer,
#else
ok &= WritePNG(fout, buffer);
#endif
} else if (format == PAM) {
ok &= WritePPM(fout, buffer, 1);
} else if (format == PPM) {
ok &= WritePPM(fout, buffer);
ok &= WritePPM(fout, buffer, 0);
} else if (format == PGM) {
ok &= WritePGM(fout, buffer);
} else if (format == ALPHA_PLANE_ONLY) {
@ -314,7 +324,8 @@ static void Help(void) {
printf("Usage: dwebp in_file [options] [-o out_file]\n\n"
"Decodes the WebP image file to PNG format [Default]\n"
"Use following options to convert into alternate image formats:\n"
" -ppm ......... save the raw RGB samples as color PPM\n"
" -pam ......... save the raw RGBA samples as a color PAM\n"
" -ppm ......... save the raw RGB samples as a color PPM\n"
" -pgm ......... save the raw YUV samples as a grayscale PGM\n"
" file with IMC4 layout.\n"
" Other options are:\n"
@ -367,6 +378,8 @@ int main(int argc, const char *argv[]) {
config.options.no_fancy_upsampling = 1;
} else if (!strcmp(argv[c], "-nofilter")) {
config.options.bypass_filtering = 1;
} else if (!strcmp(argv[c], "-pam")) {
format = PAM;
} else if (!strcmp(argv[c], "-ppm")) {
format = PPM;
} else if (!strcmp(argv[c], "-version")) {
@ -434,6 +447,9 @@ int main(int argc, const char *argv[]) {
output_buffer->colorspace = bitstream->has_alpha ? MODE_RGBA : MODE_RGB;
#endif
break;
case PAM:
output_buffer->colorspace = MODE_RGBA;
break;
case PPM:
output_buffer->colorspace = MODE_RGB; // drops alpha for PPM
break;