Choose the appropriate image format
PNG preserves transparency and uses lossless compression. JPEG suits photographs but has no transparency. WebP can balance size and quality depending on browser support.
Example and limitations
A transparent logo converted to JPEG gets a white background. Quality affects JPEG and WebP, not PNG. Renaming an extension does not convert an image; this tool actually re-encodes it.
Is a smaller size guaranteed?
No. It depends on the image, format and quality; compare the result with the original.