diff --git a/src/enc/predictor_enc.c b/src/enc/predictor_enc.c index f3715f51..802e8969 100644 --- a/src/enc/predictor_enc.c +++ b/src/enc/predictor_enc.c @@ -177,12 +177,15 @@ static uint8_t NearLosslessComponent(uint8_t value, uint8_t predict, } } +static WEBP_INLINE uint8_t NearLosslessDiff(uint8_t a, uint8_t b) { + return (uint8_t)((((int)(a) - (int)(b))) & 0xff); +} + // Quantize every component of the difference between the actual pixel value and // its prediction to a multiple of a quantization (a power of 2, not larger than // max_quantization which is a power of 2, smaller than max_diff). Take care if // value and predict have undergone subtract green, which means that red and // blue are represented as offsets from green. -#define NEAR_LOSSLESS_DIFF(a, b) (uint8_t)((((int)(a) - (int)(b))) & 0xff) static uint32_t NearLossless(uint32_t value, uint32_t predict, int max_quantization, int max_diff, int used_subtract_green) { @@ -199,7 +202,7 @@ static uint32_t NearLossless(uint32_t value, uint32_t predict, } if ((value >> 24) == 0 || (value >> 24) == 0xff) { // Preserve transparency of fully transparent or fully opaque pixels. - a = NEAR_LOSSLESS_DIFF(value >> 24, predict >> 24); + a = NearLosslessDiff(value >> 24, predict >> 24); } else { a = NearLosslessComponent(value >> 24, predict >> 24, 0xff, quantization); } @@ -212,16 +215,15 @@ static uint32_t NearLossless(uint32_t value, uint32_t predict, // The amount by which green has been adjusted during quantization. It is // subtracted from red and blue for compensation, to avoid accumulating two // quantization errors in them. - green_diff = NEAR_LOSSLESS_DIFF(new_green, value >> 8); + green_diff = NearLosslessDiff(new_green, value >> 8); } - r = NearLosslessComponent(NEAR_LOSSLESS_DIFF(value >> 16, green_diff), + r = NearLosslessComponent(NearLosslessDiff(value >> 16, green_diff), (predict >> 16) & 0xff, 0xff - new_green, quantization); - b = NearLosslessComponent(NEAR_LOSSLESS_DIFF(value, green_diff), + b = NearLosslessComponent(NearLosslessDiff(value, green_diff), predict & 0xff, 0xff - new_green, quantization); return ((uint32_t)a << 24) | ((uint32_t)r << 16) | ((uint32_t)g << 8) | b; } -#undef NEAR_LOSSLESS_DIFF #endif // (WEBP_NEAR_LOSSLESS == 1) // Stores the difference between the pixel and its prediction in "out".