PNG behaves differently from JPG
PNG compression is lossless: it reorganizes pixel data rather than discarding visual detail. The shared interface shows three preset buttons, but the current browser encoder ignores quality values for PNG. This page therefore makes no promise that Extreme will be smaller than Quality.
Good PNG candidates
Interface captures, diagrams, logos, icons, flat artwork, and images with transparency can suit PNG. Complex photographs often remain large because lossless encoding must retain every decoded colour value.
How to evaluate the result
- Add one genuine PNG.
- Run a preset; the output remains PNG at the same dimensions.
- Compare byte size. If it is not smaller, keep the original or consider another format deliberately.
When re-encoding is not enough
Large photo-like PNG files may need reduced dimensions or a format change. Read the measured format comparison before choosing WebP or JPG; those options can be smaller by accepting different trade-offs.
PNG-specific questions
Do the PNG compression levels reduce quality?
No. Browser Canvas does not expose a lossy PNG quality control, so all three choices use lossless PNG encoding and can produce the same result.
Does PNG transparency remain?
Yes. The PNG Canvas output supports alpha transparency; this page does not flatten it onto a background.
Why did the PNG not shrink?
PNG sources are often already optimized. If re-encoding is larger, FiloTool returns the original rather than replacing it with a worse result.
Should I convert PNG to WebP instead?
Possibly for web delivery, but that changes format and may use lossy compression. Keep PNG when lossless pixels or broad alpha support matter.
Does this remove metadata?
The Canvas re-encoding path writes visible pixels and ordinarily omits source metadata. Use Image Metadata when inspection and removal verification are the goal.