diff --git a/ChangeLog.md b/ChangeLog.md index ebe26b66..461931bc 100644 --- a/ChangeLog.md +++ b/ChangeLog.md @@ -22,6 +22,12 @@ djpeg. decompress a specially-crafted malformed JPEG image with a specified image width or height of 0 using the C version of TJBench. +5. The TurboJPEG API will now decompress 4:4:4 JPEG images with 2x1, 1x2, 3x1, +or 1x3 luminance and chrominance sampling factors. This is a non-standard way +of specifying 1x subsampling (normally 4:4:4 JPEGs have 1x1 luminance and +chrominance sampling factors), but the JPEG format and the libjpeg API both +allow it. + 2.0.1 ===== diff --git a/turbojpeg.c b/turbojpeg.c index 3f7cd640..b3caa0d4 100644 --- a/turbojpeg.c +++ b/turbojpeg.c @@ -359,6 +359,23 @@ static int getSubsamp(j_decompress_ptr dinfo) retval = i; break; } } + /* Handle 4:4:4 images whose sampling factors are specified in + non-standard ways. */ + if (dinfo->comp_info[0].h_samp_factor * + dinfo->comp_info[0].v_samp_factor <= + D_MAX_BLOCKS_IN_MCU / pixelsize[i] && i == TJSAMP_444) { + int match = 0; + for (k = 1; k < dinfo->num_components; k++) { + if (dinfo->comp_info[i].h_samp_factor == + dinfo->comp_info[0].h_samp_factor && + dinfo->comp_info[i].v_samp_factor == + dinfo->comp_info[0].v_samp_factor) + match++; + if (match == dinfo->num_components - 1) { + retval = i; break; + } + } + } } } return retval;