About

BPG (Better Portable Graphics) achieves 30 - 50% smaller file sizes than JPEG at equivalent visual quality by leveraging HEVC intra-frame compression. The problem: virtually no browser, image viewer, or CMS supports BPG natively. Opening a .bpg file in Windows Photos or uploading it to WordPress fails silently. This tool embeds a full HEVC decoder compiled to JavaScript, performing real decompression of transform coefficients, motion compensation, and loop filtering - identical to desktop decoders. Output quality is user-controllable; setting quality below 85% introduces visible DCT artifacts around edges. For archival photography originally shot in BPG, maintain quality at 92 - 100% to preserve detail.

Formulas

BPG stores pixel data in YCbCr color space. Conversion to RGB for JPEG output uses ITU-R BT.601 matrix transformation:

R = Y + 1.402 ⋅ (Cr − 128)

G = Y − 0.344136 ⋅ (Cb − 128) − 0.714136 ⋅ (Cr − 128)

B = Y + 1.772 ⋅ (Cb − 128)

where Y = luminance (0 - 255), Cb = blue-difference chroma, Cr = red-difference chroma. JPEG quality Q maps to quantization table scaling:

S = {

5000Q if Q < 50200 − 2Q if Q ≥ 50

where S = scaling factor applied to baseline quantization matrices. Lower Q values produce smaller files with more compression artifacts.

Reference Data

Format	Compression	Max Resolution	Color Depth	Alpha Channel	Browser Support	Typical Use Case
BPG	HEVC Intra (Lossy/Lossless)	16384 × 16384	8 - 14 bit	Yes	None	High-compression photography
JPEG	DCT (Lossy)	65535 × 65535	8 bit	No	Universal	Web images, photos
PNG	DEFLATE (Lossless)	Unlimited	1 - 16 bit	Yes	Universal	Graphics, screenshots
WebP	VP8 (Lossy/Lossless)	16383 × 16383	8 bit	Yes	Modern browsers	Web optimization
AVIF	AV1 Intra (Lossy/Lossless)	65535 × 65535	8 - 12 bit	Yes	Chrome, Firefox	Next-gen web images
HEIC	HEVC (Lossy/Lossless)	8192 × 8192	8 - 10 bit	Yes	Safari only	Apple device photos
JPEG XL	VarDCT/Modular	Unlimited	8 - 32 bit	Yes	Limited	Future replacement
TIFF	Various (LZW, ZIP)	Unlimited	1 - 32 bit	Yes	None native	Print, archival
GIF	LZW (Lossless)	65535 × 65535	8 bit indexed	Yes (1-bit)	Universal	Animations, icons
BMP	None/RLE	32767 × 32767	1 - 32 bit	Yes	Universal	Windows legacy
ICO	None/PNG	256 × 256	1 - 32 bit	Yes	Universal	Favicons, icons
SVG	XML (Vector)	Infinite	N/A	Yes	Universal	Logos, illustrations

Frequently Asked Questions

BPG uses patented HEVC/H.265 compression. Browser vendors and OS developers avoided native support due to licensing costs from MPEG-LA. You need a dedicated decoder - this tool embeds one compiled to JavaScript, performing full HEVC intra-frame decompression client-side.

Use quality 92 - 100% for archival conversion. BPG at quality 28 roughly equals JPEG at quality 80 visually. Converting BPG to JPEG below 85% compounds quantization artifacts from both encoders, degrading edges and gradients noticeably.

No. JPEG does not support alpha channels. Transparent regions are composited against white during conversion. If you need transparency, export the decoded image data to PNG instead - this tool focuses on JPEG output for maximum compatibility.

BPG employs HEVC transforms with variable block sizes (4×4 to 64×64 CTUs), advanced motion prediction repurposed for intra-frame coding, Sample Adaptive Offset filtering, and CABAC entropy coding. JPEG uses fixed 8×8 DCT blocks with simpler Huffman coding, limiting compression efficiency.

The decoder runs in browser memory. Practical limits are approximately 50MB input files or 16384×16384 pixel dimensions. Larger files may cause memory errors on devices with under 4GB RAM. Processing occurs entirely on your device - no server upload required.

HEVC decompression involves inverse integer transforms, deblocking filters, and SAO post-processing for each coding tree unit. The JavaScript decoder is slower than native implementations. A 4000×3000 pixel image typically decodes in 2 - 5 seconds depending on device CPU.