diff options
Diffstat (limited to 'drivers/webp/enc/alpha.c')
| -rw-r--r-- | drivers/webp/enc/alpha.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/drivers/webp/enc/alpha.c b/drivers/webp/enc/alpha.c index 1842b36401..03e3ad07f5 100644 --- a/drivers/webp/enc/alpha.c +++ b/drivers/webp/enc/alpha.c @@ -19,7 +19,7 @@ #include "../utils/filters.h" #include "../utils/quant_levels.h" #include "../utils/utils.h" -#include "webp/format_constants.h" +#include "../webp/format_constants.h" // ----------------------------------------------------------------------------- // Encodes the given alpha data via specified compression method 'method'. @@ -67,6 +67,11 @@ static int EncodeLossless(const uint8_t* const data, int width, int height, WebPConfigInit(&config); config.lossless = 1; + // Enable exact, or it would alter RGB values of transparent alpha, which is + // normally OK but not here since we are not encoding the input image but an + // internal encoding-related image containing necessary exact information in + // RGB channels. + config.exact = 1; config.method = effort_level; // impact is very small // Set a low default quality for encoding alpha. Ensure that Alpha quality at // lower methods (3 and below) is less than the threshold for triggering @@ -74,7 +79,11 @@ static int EncodeLossless(const uint8_t* const data, int width, int height, config.quality = 8.f * effort_level; assert(config.quality >= 0 && config.quality <= 100.f); - ok = (VP8LEncodeStream(&config, &picture, bw) == VP8_ENC_OK); + // TODO(urvang): Temporary fix to avoid generating images that trigger + // a decoder bug related to alpha with color cache. + // See: https://code.google.com/p/webp/issues/detail?id=239 + // Need to re-enable this later. + ok = (VP8LEncodeStream(&config, &picture, bw, 0 /*use_cache*/) == VP8_ENC_OK); WebPPictureFree(&picture); ok = ok && !bw->error_; if (!ok) { @@ -113,7 +122,6 @@ static int EncodeAlphaInternal(const uint8_t* const data, int width, int height, assert(method >= ALPHA_NO_COMPRESSION); assert(method <= ALPHA_LOSSLESS_COMPRESSION); assert(sizeof(header) == ALPHA_HEADER_LEN); - // TODO(skal): have a common function and #define's to validate alpha params. filter_func = WebPFilters[filter]; if (filter_func != NULL) { |