Image Transparency
What image transparency is, which formats support alpha channels, and how transparency works in screenshots and exports.
Image transparency lets some pixels be fully or partly see-through, so the background behind the image shows. It is stored in an alpha channel, an extra value per pixel next to red, green and blue. In 8-bit images, alpha 0 is fully transparent and alpha 255 is fully opaque.
Partial alpha values allow soft edges, shadows and glass effects. Images store alpha either straight, with color and opacity separate, or premultiplied, with color already multiplied by opacity. Mixing up the two produces dark or light fringes at edges.
Some formats have only binary transparency: a pixel is either fully visible or fully transparent.
Convert image formats
Converting to a format without alpha removes transparency. Image Converter converts between PNG, JPG and WebP; choose PNG or WebP to keep it.
How transparency works
When an image with alpha is drawn, each pixel is blended with what is behind it in proportion to its opacity. A logo with a soft shadow on a transparent PNG blends correctly on white, gray or a photo. When the same image is flattened, the background color is fixed into the pixels.
Formats that support transparency
| Format | Transparency |
|---|---|
| PNG | Full alpha, 8 or 16 bits |
| WebP | Full alpha, lossy or lossless |
| AVIF and HEIC | Full alpha |
| TIFF | Full alpha |
| GIF | Binary, one transparent palette color |
| JPG | None |
| SVG | Opacity per shape |
Transparency and screenshots
Most screenshots are fully opaque, because they record a rectangle of the screen. On macOS, a window capture made with Shift+Command+4 and then Space can include the window shadow with transparent surroundings, saved as PNG. Exporting such an image to JPG fills the transparent area with a solid color.
Common mistakes
- Saving a transparent logo as JPG.
- Using GIF for soft shadows, which gives jagged edges.
- Placing a transparent dark icon on a dark background where it disappears.
- Previewing on a white background only.
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Common questions
Does WebP support transparency?
Yes, in both lossy and lossless modes.
Why did my transparent image get a black background?
The app that opened or converted it does not support alpha, or flattened it onto black.
Sources
Related resources
- Image background removal: making a background transparent.
- Export formats: PNG and WebP exports.
Taking the same screenshots again and again?
Temposhot captures a screen, window or area on a timer and exports the set as a PDF, images, ZIP or MP4. The free browser tools fix single images.
Related resources
Related terms
- PNGHow the PNG image format works, when to use it for screenshots, and how it compares to JPG and WebP.
- Image Background RemovalHow image background removal works, where it is used, and the difference between AI-powered and manual removal techniques.
- WebPWhat WebP is, how it compares to PNG and JPG, and when to use it for screenshots.
- GIFWhat GIF is, how it compares to video formats, and when animated GIFs are the right choice for motion content.
- Image FormatOverview of common image formats — PNG, JPG, WebP, AVIF — and when to use each.