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.
2 files changed