Image guide · Updated September 19, 2026
Choose JPEG, PNG, WebP, or AVIF for the actual image
Use the receiving app’s format support, the image’s detail, and the need for transparency before chasing the smallest number.
JPEG: a familiar choice for opaque photos
JPEG is widely used for continuous-tone photographs. It has no transparency. Fine text and sharp colored edges can develop visible ringing at low quality, so a screenshot is a poor test of how a photograph will look. The Compress JPG page starts with JPEG selected; a transparent source still needs an explicit background choice.
PNG: crisp graphics and lossless pixels
PNG is useful for screenshots, small diagrams, and graphics with transparency when preserving the prepared pixel values matters. Detailed photographic content can be much larger as PNG than as a lossy format. In MallowDesk, its quality preset changes optimization effort, not a lossy color threshold.
WebP: a useful web delivery option
WebP supports transparency and can reduce bytes for many images. MallowDesk’s WebP output uses lossy encoding, so compare small text and thin edges rather than assuming it is identical to PNG. Confirm that the site, editor, or upload form accepts WebP before converting an entire batch.
AVIF: compare savings against processing time
AVIF supports transparency and can produce compact results, but encoding is more computationally expensive. Target mode samples fewer AVIF quality levels to bound repeated work. Our app outputs 8-bit images; it does not promise to preserve HDR or wide-gamut color. A smaller AVIF is not useful if the receiving app rejects it.
How to make a fair comparison
Start each format from the same original, at the same dimensions. Repeatedly converting a lossy JPEG to another lossy format compounds changes and makes the comparison misleading. Equal quality numbers across codecs are not equal visual quality. Compare actual output files at the intended display size, then inspect a close view for artifacts.
Use examples as evidence, not a ranking
Our examples label synthetic textures, gradients, transparent graphics, and text separately. Their byte counts are measurements for those files and settings, not predictions for your photograph. Download a source and reproduce the settings, then try your own image. Preserve the original so another format choice remains possible.
Try it with a reproducible example
Open the source files, measured outputs, and settings. Use the same source for each comparison and inspect the actual result.