Convert JPG to PNG

Lossless does not mean the quality comes back

PNG is a lossless format, which means it will not discard anything when it saves. That is a real property, and it matters for the next edit. But the JPG you are converting has already discarded detail, and PNG cannot restore what is not there. So converting to PNG makes your file larger without improving the picture. What it does is protect the current quality from further loss, which is genuinely useful if you are about to edit the file again.

• PNG will not lose anything further, so repeated saves are safe.
• It cannot recover detail the JPG discarded at the moment it was created.
• The file will be noticeably larger, often several times the JPG.
• It adds no transparency, because JPG has no alpha channel to carry across.

NoteThe honest reason to convert a JPG to PNG is to make further edits safely, not to make the existing image sharper.

The real reason: text and hard edges

A JPG stores a photograph well and an edge badly, because the compression works on blocks of colour and a sharp boundary between two colours is expensive to represent. Text is the worst case, and so are logos, screenshots, and diagrams. Converting such an image to PNG stops any further softening, which helps when you are about to add text to it, crop it repeatedly, or hand it to a printer. It does not repair edges that are already broken in the JPG.

• Text, logos, and diagrams benefit from lossless storage, especially before further editing.
• A screenshot saved as JPG has already blurred its text. PNG preserves what is left, no more.
• If text is critical, re-capture or re-export from the original rather than converting.
• For a pure photograph, the JPG to PNG conversion is usually not worth the file size.

Size, and when it is genuinely the wrong tool

A 4 megapixel photograph is often around 1 MB as a JPG and can exceed 5 MB as a PNG. That is a real cost when uploading to a form with a size limit or attaching to an email. So the decision is straightforward: if the image is a photograph that does not need further editing, keep the JPG. If it needs lossless handling, or contains text or graphic edges, convert to PNG and accept the size. If the size limit is the binding constraint, then the answer is a different tool, not a different extension.

What does not change

The pixel dimensions are identical, and no new detail appears. What differs is the storage method and the file size, and whether the result can be edited again without further loss. It is worth being clear about this because "lossless" is often read as "better", and here it means "will not get worse from here", which is a smaller promise than people expect.

• Dimensions and visible content are unchanged.
• No sharpness or detail is added.
• File size increases substantially.
• Transparency is not added, because there is none to carry over.
• Further edits will not degrade the file, which is the actual benefit.