How to convert images without losing quality
What "losing quality" actually means, when it is unavoidable, and how to pick a format and a setting so the loss is invisible.
Published 3 Aug 2026 by the FlipMyFile team
Almost every guide on this subject starts by promising lossless conversion and then quietly recommends a lossy format. Let us be more precise than that, because the precision is what lets you make a good decision.
Two completely different kinds of loss
The first kind is compression loss. JPG, lossy WebP and AVIF all work by discarding information your eye is bad at noticing — fine gradations in busy areas, subtle colour shifts. Once discarded it is gone, and no later conversion brings it back.
The second kind is generation loss, and it is the one that actually ruins images. Every time you open a JPG and save it again, the encoder throws away a little more. Do that five times and the difference is obvious. This is why an image that has been forwarded through three chat apps looks like it was photographed off a screen.
When conversion is genuinely lossless
Converting into a lossless format never adds new damage. PNG to PNG, JPG to PNG, WebP to PNG — none of these degrade anything. What they cannot do is repair damage that is already baked in. A JPG converted to PNG is a perfect copy of a lossy image.
This trips people up constantly. Converting a blurry JPG to PNG does not sharpen it; it just makes the file five times larger while preserving every artefact exactly.
Picking the right target format
| If your image is… | Use | Why |
|---|---|---|
| A photograph for the web | WebP at 82 | Same look as JPG 90, roughly 30% smaller |
| A photograph that must open anywhere | JPG at 85 | Universally supported, loss invisible |
| A logo, icon or screenshot | PNG or WebP | Sharp edges survive; JPG smears them |
| Anything with transparency | PNG or WebP | JPG has no alpha channel at all |
| An archive master copy | PNG | Lossless, so re-editing costs nothing |
The quality number, demystified
Quality settings are not percentages of anything. Quality 50 does not mean "half as good". They are encoder parameters with a non-linear relationship to what you see.
- JPG 90–100: file size climbs steeply for a difference you will not see. Rarely worth it.
- JPG 80–85: the sweet spot for photographs. This is where almost everything should sit.
- JPG 70–80: acceptable for background images and thumbnails.
- Below 70: blocky edges appear around text and hard lines. Visible on screenshots long before it is visible on photos.
WebP sits about eight points lower for the same perceived quality — WebP 82 looks like JPG 90. That gap is the entire reason the format exists.
What about transparency
JPG cannot store transparency. Not "poorly" — at all. Every transparent pixel has to be replaced with a solid colour when you convert. If a tool does this without asking, you usually get black, and the result looks broken.
This is why our PNG to JPG tool asks which colour should replace transparency before it does anything, and defaults to white. If keeping transparency matters, convert to WebP instead — it has a full alpha channel and still produces much smaller files than PNG.
A practical checklist
- Start from the original file, not from an earlier conversion.
- Photograph destined for the web? WebP at 82.
- Needs to open in any program at all? JPG at 85.
- Has transparency or sharp edges? Stay lossless — PNG or WebP.
- Compare the before and after size. If the saving is tiny, the file was already compressed and you are only losing quality.
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