diff options
| -rw-r--r-- | bin/pngo.c | 38 |
1 files changed, 23 insertions, 15 deletions
diff --git a/bin/pngo.c b/bin/pngo.c index 6dd88c87..425d4a9a 100644 --- a/bin/pngo.c +++ b/bin/pngo.c @@ -97,13 +97,13 @@ struct PACKED Header { }; static uint8_t bytesPerPixel(struct Header header) { - assert(header.depth == 8); + assert(header.depth >= 8); switch (header.color) { - case GRAYSCALE: return 1; - case TRUECOLOR: return 3; - case INDEXED: return 1; - case GRAYSCALE_ALPHA: return 2; - case TRUECOLOR_ALPHA: return 4; + case GRAYSCALE: return 1 * header.depth / 8; + case TRUECOLOR: return 3 * header.depth / 8; + case INDEXED: return 1 * header.depth / 8; + case GRAYSCALE_ALPHA: return 2 * header.depth / 8; + case TRUECOLOR_ALPHA: return 4 * header.depth / 8; } } @@ -220,6 +220,7 @@ enum PACKED FilterType { FILT_AVERAGE, FILT_PAETH, }; +#define FILT__COUNT (FILT_PAETH + 1) struct FilterBytes { uint8_t x; @@ -230,9 +231,9 @@ struct FilterBytes { static uint8_t paethPredictor(struct FilterBytes f) { int32_t p = (int32_t)f.a + (int32_t)f.b - (int32_t)f.c; - int32_t pa = labs(p - (int32_t)f.a); - int32_t pb = labs(p - (int32_t)f.b); - int32_t pc = labs(p - (int32_t)f.c); + int32_t pa = abs(p - (int32_t)f.a); + int32_t pb = abs(p - (int32_t)f.b); + int32_t pc = abs(p - (int32_t)f.c); if (pa <= pb && pa <= pc) return f.a; if (pb <= pc) return f.b; return f.c; @@ -273,7 +274,7 @@ static struct Scanline *scanlines( for (uint32_t y = 0; y < header.height; ++y) { lines[y].type = &data[y * stride]; lines[y].data = &data[y * stride + 1]; - if (*lines[y].type > FILT_PAETH) { + if (*lines[y].type >= FILT__COUNT) { errx(EX_DATAERR, "%s: invalid filter type %hhu", path, *lines[y].type); } } @@ -307,11 +308,18 @@ static void reconData(struct Header header, const struct Scanline *lines) { static void filterData(struct Header header, const struct Scanline *lines) { uint8_t bpp = bytesPerPixel(header); for (uint32_t y = header.height - 1; y < header.height; --y) { - // TODO: Filter type heuristic. - *lines[y].type = FILT_PAETH; - for (uint32_t i = (bpp * header.width) - 1; i < bpp * header.width; --i) { - lines[y].data[i] = filt(*lines[y].type, filterBytes(lines, bpp, y, i)); + uint8_t filter[FILT__COUNT][bpp * header.width]; + uint32_t heuristic[FILT__COUNT] = { 0 }; + enum FilterType minType = FILT_NONE; + for (enum FilterType type = FILT_NONE; type < FILT__COUNT; ++type) { + for (uint32_t i = 0; i < bpp * header.width; ++i) { + filter[type][i] = filt(type, filterBytes(lines, bpp, y, i)); + heuristic[type] += abs((int8_t)filter[type][i]); + } + if (heuristic[type] < heuristic[minType]) minType = type; } + *lines[y].type = minType; + memcpy(lines[y].data, filter[minType], bpp * header.width); } } @@ -380,7 +388,7 @@ int main(int argc, char *argv[]) { path, header.interlace ); } - if (header.depth != 8) { + if (header.depth < 8) { errx(EX_CONFIG, "%s: unsupported bit depth %hhu", path, header.depth); } |