Guide
Image formats for game art
There are a lot of image formats and most advice about them is written for photographers. Here is the version for people shipping sprites and textures.
The short answer
- Sprites, UI, anything with transparency: PNG. Lossless, universally supported, alpha channel. This is the default and you rarely need to argue with it.
- Large photographic textures with no transparency: JPEG if size matters and you can accept artefacts, otherwise PNG.
- Web delivery: WebP, which is smaller than both at comparable quality and supports alpha.
- Source art you will edit again: PSD or TIFF, which keep layers or lossless full-depth data.
- Lighting data, HDRI skies: EXR or HDR, which store values brighter than white.
Lossless versus lossy
A lossless format reproduces every pixel exactly as it was written. A lossy format throws away information the encoder judges you will not notice, in exchange for a smaller file.
For game art, that judgement is often wrong. Lossy compression is tuned for photographs — smooth gradients, natural noise, no hard edges. Pixel art and UI are the opposite: flat colour, hard edges, thin lines. JPEG puts visible ringing around a one-pixel outline and mottles a flat background.
Lossy artefacts also accumulate. Every time you open a JPEG, change something and re-save it, the encoder re-quantises what the last pass already damaged. Keep a lossless master and export lossy copies from it, rather than editing the lossy copy repeatedly.
Transparency
If your art has any transparency at all — a sprite with a shaped outline, a UI panel with rounded corners, a particle with a soft edge — you need a format with an alpha channel. That rules out JPEG entirely, and it rules out HDR (Radiance), which stores three colour channels and a shared exponent but no alpha.
When you export to a format that cannot carry alpha, the transparency has to go somewhere. It gets flattened onto a background colour, white by default. A sprite that looked correct with a soft shadow will come out with a white halo. This is the single most common surprise when exporting to JPEG.
The formats, one at a time
| Format | Alpha | Compression | Use it for |
|---|---|---|---|
| PNG | Yes | Lossless | The default for sprites, UI and anything with transparency. |
| JPEG | No | Lossy | Large photographic textures where file size dominates and there is no transparency. |
| WebP | Yes | Both | Web delivery. Smaller than PNG losslessly, and smaller than JPEG lossily, with alpha in both modes. |
| AVIF | Yes | Both | Newer and smaller still, at the cost of slower encoding and patchier tool support. |
| TIFF | Yes | Usually lossless | An interchange format for print and scanning pipelines. Flexible to the point of being unpredictable — many "TIFF" files use compression a given tool cannot read. |
| TGA | Yes | None or RLE | A very old, very simple format. Still common in game pipelines precisely because nothing about it is clever. |
| PSD | Yes | RLE | Photoshop working files. Keeps layers; large. A flattened composite is stored alongside, which is what viewers display. |
| DDS | Yes | Block (BC1–BC7) | Textures compressed in the form the GPU reads directly, so they stay compressed in video memory. |
| HDR | No | RLE | Radiance format. Environment maps and lighting probes. |
| EXR | Yes | Several | The film and VFX standard for high dynamic range, with float precision and arbitrary channels. |
| GIF | 1-bit | Lossless, 256 colours | Little reason to use it for new art. Transparency is on or off per pixel, with no partial opacity. |
A note on DDS and block compression
DDS is different in kind from the others. Where PNG compresses an image to store it and then decompresses it fully into memory, DDS holds a block-compressed texture that the GPU samples while still compressed. A BC1 texture uses about a sixth of the memory of the raw version, permanently.
That is a large win, and it costs quality. Block compression works on 4×4 pixel groups and approximates the colours in each. It is fine for organic surfaces and noticeably poor for sharp gradients and text. It is also lossy and irreversible, so keep the PNG or TGA the DDS was built from.
High dynamic range
Ordinary formats store each channel as a value between 0 and 255, where 255 means "as bright as white". That cannot represent a sun, a bright window or a specular highlight several times brighter than paper white.
HDR and EXR store floating point values with no upper bound. This matters for image-based lighting: an HDRI sky used as a light source needs the sun to be genuinely thousands of times brighter than the sky around it.
The consequence for viewing is that any HDR image has to be tone-mapped down to be shown on an ordinary screen, and different tools make different choices about how. CropViewer clamps linearly, which is predictable, but it means very bright areas display as flat white — they are not clipped in the file, only in the preview.
Choosing an export format in CropViewer
CropViewer opens PNG, JPEG, WebP, GIF, BMP, AVIF, TIFF, TGA, PSD, DDS, HDR and EXR, and exports to PNG, JPEG, WebP, TIFF, BMP, TGA, HDR and EXR. Save As offers the options that matter for each: compression level for PNG, quality and progressive encoding for JPEG, lossless mode for WebP.
If you are unsure, export PNG. It is lossless, it keeps your alpha, and every tool downstream will read it.