kc3-lang/libjpeg-turbo

2015-08-29T18:05:43

Fix negative shift with IFAST FDCT and qual=100 With certain images, compressing using quality=100 and the fast integer forward DCT will cause the divisor passed to compute_reciprocal() to be 1. In those cases, the library already disables the SIMD quantization algorithm to avoid 16-bit overflow. However, compute_reciprocal() doesn't properly handle the divisor==1 case, so we need to use special values in that case so that the C quantization algorithm will behave like an identity function.