Still Picture profile allows for a single still picture to be encoded with the same constraints as the Main profile. As a subset of the Main profile the Main Still Picture profile allows for a bit depth of 8 bits per sample with 4:2:0 chroma sampling. An objective performance comparison was done in April 2012 in which HEVC reduced the average bit rate for images by 56% compared to JPEG. A PSNR based performance comparison for still image compression was done in May 2012 using the HEVC HM 6.0 encoder and the reference software encoders for the other standards. For still images HEVC reduced the average bit rate by 15.8% compared to H.264/MPEG-4 AVC, 22.6% compared to JPEG 2000, 30.0% compared to JPEG XR, 31.0% compared to WebP, and 43.0% compared to JPEG. A performance comparison for still image compression was done in January 2013 using the HEVC HM 8.0rc2 encoder, Kakadu version 6.0 for JPEG 2000, and IJG version 6b for JPEG. The performance comparison used PSNR for the objective assessment and mean opinion score (MOS) values for the subjective assessment. The subjective assessment used the same test methodology and images as those used by the JPEG committee when it evaluated JPEG XR. For 4:2:0 chroma sampled images the average bit rate reduction for HEVC compared to JPEG 2000 was 20.26% for PSNR and 30.96% for MOS while compared to JPEG it was 61.63% for PSNR and 43.10% for MOS. A PSNR based HEVC performance comparison for still image compression was done in April 2013 by Nokia. HEVC has a larger performance improvement for higher resolution images than lower resolution images and a larger performance improvement for lower bit rates than higher bit rates. For lossy compression to get the same PSNR as HEVC took on average 1.4× more bits with JPEG 2000, 1.6× more bits with JPEG-XR, and 2.3× more bits with JPEG. A compression efficiency study of HEVC, JPEG, JPEG XR, and WebP was done in October 2013 by Mozilla. The study showed that HEVC was significantly better at compression than the other image formats that were tested. Four different methods for comparing image quality were used in the study which were Y-SSIM, RGB-SSIM, IW-SSIM, and PSNR-HVS-M. Version 2 profiles Version 2 of HEVC adds 21 range extensions profiles, two scalable extensions profiles, and one multi-view profile: Monochrome, Monochrome 12, Monochrome 16, Main 12, Main 4:2:2 10,