QOI to JPG Converter

Encoding: the QOI uses lossless, byte-aligned run, index, difference and literal codes; JPG uses lossy DCT coding in 8×8 pixel blocks, with colour usually stored at half resolution, and the download is a standard JPEG at the quality you choose.

Bit depth: 8 bits per channel in the QOI; JPG allows 8 bits per channel, and the JPG written here has 8 bits per channel.

Colour: RGB or RGBA, tagged sRGB or linear in the QOI; JPG supports YCbCr shown as RGB, greyscale, or CMYK from print software, written here as 8-bit sRGB.

Transparency: the QOI stores it as a full 8-bit alpha channel; the JPG has none, so transparent areas are filled with the colour you choose.

Metadata: the QOI can carry none: a 14-byte header holds only size, channels and colour space; JPG can carry EXIF (camera, date, GPS), XMP, IPTC and an ICC profile in APP segments, but nothing is copied across.

QOI is a modern lossless format that encodes 20-50 times faster than PNG with similar file sizes. It is popular in games and tools that value speed and simplicity.

A QOI file is a 14-byte header ('qoif', width, height, channels, colour space), a stream of chunks that each encode a run, an index into 64 recently seen colours, a small difference from the previous pixel or a literal value, and an 8-byte end marker.

QOI files usually come from game engines, emulators and tools that want lossless images without a PNG library.

JPEG is the universal photo format. It compresses by discarding fine detail the eye is least sensitive to, which makes photos small but blurs sharp edges and text if pushed too far.

A JPEG starts with the bytes FF D8 and is a run of marker segments: APP1 carries EXIF and often a thumbnail, APP2 an ICC profile, DQT the quantization tables that decide the quality, and SOS the compressed scan, which ends at FF D9.

JPG is the better choice for photographs that need to open anywhere, while QOI suits fast lossless storage in games and tools.

JPG strengths: Opens everywhere: every browser, phone, camera, printer and app; Small files for photographs; Adjustable quality from tiny to near-lossless. Drawbacks to weigh: No transparency; Lossy: every re-save loses a little more; Blocky artifacts around text, logos and sharp lines.