PNG to JPG
What PNG to JPG actually does
This is the one conversion that destroys something, and the thing it destroys is the part most converters handle worst. A PNG can be transparent. A JPG cannot. Anything transparent has to be painted over with a solid colour before the JPG is written, and a converter that does not ask fills it with whatever its canvas defaulted to, which is usually black. That is where the black box around a logo comes from. Here the fill colour is a control that appears the moment a file carrying transparency is in the queue, defaulted to white because that is what most documents sit on, and the conversion paints the chosen colour underneath the picture rather than letting the encoder guess. The quality setting is the other half of the trade: a JPG is smaller than a PNG because it throws detail away, and the size of each result is reported next to the size it started at.
How to use it
- Add the PNG files. Anything transparent is flagged on its row.
- Choose the colour that replaces the transparent areas, then choose the quality. Higher keeps more detail and costs more bytes.
- Convert and compare the before and after sizes on each row before downloading.
Useful for
- Shrink a screenshot or an export that a PNG makes needlessly large.
- Meet an upload limit on a form that will not take a PNG.
- Put a logo with a transparent background onto a solid colour deliberately rather than accidentally.
Limits worth knowing
- The transparency is gone once converted. Keep the PNG if the cutout is still needed.
- A soft or feathered edge blends into the fill colour, so an edge meant for a dark page looks wrong on white.
- Text and flat graphics compress badly as JPG and can show ringing around the letters. A PNG or a WebP holds them better.
- Colour profiles are not carried through.
Questions people ask
Why does my transparent PNG go black in other converters?
An empty canvas is transparent black, and drawing a transparent image onto it leaves those pixels as they were. The JPEG encoder then discards the alpha channel and keeps the black. Painting a colour first is the fix, and it is why the fill control exists.
Which quality should I choose?
Eighty to ninety suits photographs. Below about seventy the artefacts start to show on flat colour and around text.
Can I convert a folder of them at once?
Yes. Add as many as sixty, and each one reports its own size change.