Why it helps to know image formats
Game development involves a lot of images: characters, backgrounds, UI, icons, and more. Images come in many file formats, such as PNG and JPEG, and the format affects image quality, file size, and whether transparent areas are supported.
Choosing an unsuitable format can result in blurry images, white boxes around transparent backgrounds, or unnecessarily large files. Understanding the differences between formats can help you avoid these problems.
Three differences to know first
1. Lossless and lossy compression
Images are large when stored as-is, so most formats compress the data. There are two main kinds of compression.
- Lossless compression: The original image can be restored exactly. There is no loss in quality, but the file tends to be larger.
- Lossy compression: Information that has little effect on how the image looks is discarded to make the file smaller. The file gets smaller, but the image quality is reduced.
2. Whether transparency is supported
To place a character with a transparent background over your game screen, you need a format that supports transparency. If you save in a format that does not, the transparent areas are filled in, usually with white.
3. Limits on colors and animation
Some formats limit the number of colors you can use, and some can store animation. Converting an image with many colors, such as a photo, to a format with few colors can change its look a lot.
Comparison of the main formats
| Format | Compression | Transparency | Characteristics |
|---|---|---|---|
| PNG | Lossless | Supported | The standard format with no loss in quality. Files are somewhat large. |
| JPEG | Lossy | Not supported | Suited to photos. Small files, but quality drops with each save. |
| WebP | Lossless or lossy | Supported | Better compression than PNG and JPEG. Also supports animation. |
| GIF | Lossless (up to 256 colors) | Fully transparent or opaque only | Used for simple animations. Strong color limits. |
| BMP | Uncompressed | Not supported | Simple and highly compatible, but files are large. |
| AVIF | Mainly lossy | Supported | A newer format with high compression and small files. Some browsers cannot read it. |
| SVG | Vector | Supported | Stays sharp at any size. Stores shapes instead of pixels. |
| ICO | Bundles multiple sizes | Supported | For favicons and application icons. |
Characteristics of each format
PNG
PNG uses lossless compression and supports transparency. Because quality does not degrade, it suits pixel art, UI, and illustrations where you want crisp edges. When in doubt, start with PNG and you are unlikely to go far wrong. Files can get large for images with many colors, such as photos.
JPEG
JPEG uses lossy compression and makes small files easily. It suits photos and backgrounds where colors change smoothly. It does not support transparency, so transparent areas become white or similar. It also tends to produce blocky noise around edges, so it is not suited to pixel art or sharp line art.
WebP
Developed by Google, WebP lets you choose lossless or lossy compression. It supports transparency, and its strength is that it can make files smaller than PNG or JPEG at similar quality. For web games running in the browser, it is a strong choice when you want lighter loading. However, some game engines may not import it, so check the formats your engine supports first.
GIF
GIF is limited to 256 colors and is used for simple animations. Transparency is all or nothing: a pixel is either transparent or opaque, with no semi-transparency. It works for assets with few colors, but PNG is more common for game assets.
BMP
BMP is a simple, uncompressed format. Its compatibility is high, but its files are large, so there are few occasions to use it for game assets.
AVIF
AVIF is a newer format that is light thanks to its high compression. However, depending on your environment, it may not be readable. If you use it in a game you distribute, check its support first.
SVG
SVG is a vector format that describes a picture with lines and shapes rather than pixels. It stays sharp when enlarged, so it suits logos and simple icons. It is not suited to photos or to pixel art drawn dot by dot.
ICO
ICO is an icon-specific format used for favicons and application icons. Its feature is that it can hold several sizes, such as 16 px, 32 px, and 256 px, in a single file.
Choosing a format for game development
| Use | Recommended format | Why |
|---|---|---|
| Pixel art and sprites | PNG | No loss in quality and transparency is available. JPEG blurs the edges. |
| UI and icon assets | PNG | Transparency is available and edges stay crisp. |
| Photos and realistic backgrounds | JPEG / WebP | Keeps files small even for images with many colors. |
| Lighter assets for a web game | WebP | Can be smaller than PNG and JPEG, so loading is faster. |
| Logos and simple shapes | SVG | Stays sharp at any size. |
| Site favicons and app icons | ICO / PNG | Multiple sizes can be bundled (ICO). |
Keep your original working files in a lossless format such as PNG, and convert them to the format you need when you distribute the game.
What to watch for when converting
- Lost quality does not come back: Converting a JPEG to PNG does not restore the quality that was already lost. Converting from one lossy format to another can reduce quality further.
- Transparency can be lost: JPEG and BMP have no transparency, so transparent areas are replaced with white. In GIF, semi-transparent pixels become either fully transparent or opaque.
- Colors can be reduced: Converting to GIF limits the image to 256 colors.
- Animation may keep only the first frame: When you convert an animated GIF or similar, only the first frame may be converted.
- SVG becomes a fixed-size image: Converting SVG to another format turns it into a regular pixel image, which gets rough when enlarged.
Convert with our tool
Our Image Format Converter lets you choose an image and convert it to PNG, JPEG, WebP, GIF, BMP, or ICO. The source format is detected automatically, and everything is processed in your browser, so your images are never sent to a server. You can also set the JPEG quality and choose lossless or lossy for WebP.
Format support can differ depending on your browser and your game engine version. Be sure to also check the official documentation for the environment you use.