BPG Image format

News

(Apr 21 2018) Release 0.9.8 is available.
An online BPG encoder and viewer.

Introduction

BPG (Better Portable Graphics) is a new image format. Its purpose is to replace the JPEG image format when quality or file size is an issue. Its main advantages are:

High compression ratio. Files are much smaller than JPEG for similar quality.
Supported by most Web browsers with a small Javascript decoder (gzipped size: 56 KB).
Based on a subset of the HEVC open video compression standard.
Supports the same chroma formats as JPEG (grayscale, YCbCr 4:2:0, 4:2:2, 4:4:4) to reduce the losses during the conversion. An alpha channel is supported. The RGB, YCgCo and CMYK color spaces are also supported.
Native support of 8 to 14 bits per channel for a higher dynamic range.
Lossless compression is supported.
Various metadata (such as EXIF, ICC profile, XMP) can be included.
Animation support.

Download

The following archive contains the source code of the bpgenc, bpgdec and bpgview command line utilities (for Linux) and the associated libbpg library (read the README file in the archive). It also includes the source code of the Javascript decoder.

libbpg-0.9.8.tar.gz

Binary distribution for Windows (64 bit only): bpg-0.9.8-win64.zip

Unofficial Github mirror.

For Mac users, the BPG utilities are available in the libbpg Homebrew formula.

Performance

Mozilla did a study of various lossy compressed image formats. HEVC (hence BPG) was a clear winner by a wide margin. BPG files are actually a little smaller than raw HEVC files because the BPG header is smaller than the corresponding HEVC header.
BPG natively supports 8 to 14 bits per channel when most other formats use 8 bits (including most of the JPEG implementations and WEBP). It gives a higher dynamic range (which is important for cameras and new displays) and a slightly better compression ratio (because there are less rounding errors in the decoder).
BPG uses high quality decimation (10 tap Lanczos filter) and interpolation (7 tap Lanczos filter) to handle the chroma samples in 4:2:2 and 4:2:0 formats.
BPG can be supported in hardware with standard HEVC decoders and encoders (it uses a subset of the Main 4:4:4 16 Still Picture Profile, Level 8.5).

Demo

Visual comparison between BPG (x265 encoder), JPEG (mozjpeg encoder), JP2K and WebP
Lena 512x512 image, visual comparison with JPEG
Wikipedia photos
Images with alpha channel
Test images using different color spaces and bit depth
Test animations

Technical information

The specification of the BPG file format is available here.

Licensing

The BPG decoding library uses a modified version of FFmpeg released under the LGPL version 2.1 as HEVC decoder. The BPG decoding library excluding the FFmpeg code is released under the BSD license.
The BPG encoder as a whole is released under the GPL version 2 license. The BPG encoder sources excluding x265 are released under the BSD license. The x265 library is released under the GPL version 2 license. The optional JCTVC HEVC reference encoder is released under the BSD license.
Some of the HEVC algorithms may be protected by patents in some countries (read the FFmpeg Patent Mini-FAQ for more information). Most devices already include or will include hardware HEVC support, so we suggest to use it if patents are an issue.

Fabrice Bellard - http://bellard.org/