Hi Nathan,
Output with trunk: Value: 12632255 Should be: 1073741823
There was already a bug in the code before I patched it. Basically the static_cast to integer_t should have been applied to src only. Please review my patch. The function is more verbose now but I thing it's more clear. Index: channel_algorithm.hpp =================================================================== --- channel_algorithm.hpp (revision 66416) +++ channel_algorithm.hpp (working copy) @@ -226,8 +226,20 @@ template <typename SrcChannelV, typename DstChannelV> struct channel_converter_unsigned_integral_nondivisible<SrcChannelV,DstChannelV,true,false> { DstChannelV operator()(SrcChannelV src) const { - typedef typename base_channel_type<DstChannelV>::type dest_t; - return DstChannelV(static_cast<dest_t>( src * unsigned_integral_max_value<DstChannelV>::value) / unsigned_integral_max_value<SrcChannelV>::value); + + // make sure the operation below doesn't overflow dst's integeral data type. + // e.g. dst is 30bit and src is 8 bit can result in 38bit value + typedef typename detail::min_fast_uint< unsigned_integral_num_bits< SrcChannelV >::value + + unsigned_integral_num_bits< DstChannelV >::value + >::type integer_t; + + typedef typename base_channel_type< DstChannelV >::type dest_t; + + integer_t src_ = static_cast< integer_t >( src ); + integer_t dst_max = unsigned_integral_max_value<DstChannelV>::value; + integer_t src_max = unsigned_integral_max_value<SrcChannelV>::value; + + return static_cast< dest_t >( src_ * dst_max / src_max ); } }; Regards, Christian