By CutImage · Updated
A good format depends on the pixels and where they will be used. A photograph, a transparent logo and a screenshot have different failure modes. Choose based on the result you can inspect, then confirm the destination accepts that file type.
| Format | Useful starting point | Watch for |
|---|---|---|
| JPEG | Opaque photographs and broad upload compatibility | No transparency; ringing or blocks around text |
| PNG | Transparent graphics, diagrams and crisp screenshots | Large files for detailed photographs |
| WebP | Web delivery with adjustable quality and transparency | The receiving app must accept WebP; compare edges at your selected quality |
Photographs: compare JPEG and WebP
Start by resizing to the required dimensions. Export a JPEG or WebP around 80% quality and compare the result with the source. Look at hair, foliage, shadow gradients and high-contrast edges. If artifacts are visible, increase quality or keep more pixels.
Two files at “80%” are not equivalent across formats or browser encoders. The slider is an input to the encoder, not a measurement of the percentage of original detail retained. A smaller file is useful only if it still meets the visual requirement.
Logos and screenshots: inspect edges and transparency
For a logo with a transparent background, PNG is a straightforward lossless pixel encoding. WebP also supports alpha, but CutImage’s quality slider uses a lossy export path, so inspect small lettering. JPEG fills transparent areas with white in this converter. That can suit a white page but will show a box on a dark background.
For a screenshot with small interface text, try PNG first. Compare with a WebP export at the same dimensions. Thin lines and text halos are easier to notice at 100% zoom than in a small thumbnail. If you have the original vector logo, using that original SVG on your website may be better than rasterizing it and tracing it back.
What “lossless” does and does not mean here
PNG encodes its input pixels without the lossy quantization used by JPEG. It cannot reverse damage already in a JPEG source. A JPEG-to-PNG conversion can therefore be much larger while looking the same. Browser decoding, color conversion and Canvas export also mean this is not an archival metadata-preserving workflow.
A practical comparison workflow
- Keep the original and create the intended dimensions with Resize.
- Use Convert to export PNG, JPEG or WebP.
- Compare the output size and inspect the downloaded file at its intended display scale.
- Confirm the destination accepts the format and that transparency behaves as expected.
CutImage does not encode AVIF, GIF, BMP or JPEG XL. Browser-readable animated inputs become still images in this workflow. If animation, a particular color profile or editable layers matter, keep a workflow designed for those requirements.
Format reference: MDN’s image file type guide.