How to convert files without unnecessary quality loss
Note: General information only. Check the requirements of the app, service or recipient that will use the file.
A conversion does not always reduce quality. The main risk is encoding a file with lossy compression, especially when you repeatedly re-encode an already compressed copy. Keep the original and check the exported result before replacing anything.
Lossless and lossy formats
Lossless compression preserves the encoded pixel data when it is decoded. PNG is a lossless format, which can suit screenshots, text and graphics with flat areas. Lossy formats such as JPEG discard some image information to reduce file size; the visible effect depends on the image and encoding settings.
Saving an edited JPEG again can introduce additional loss if the app decodes and re-encodes it. The amount varies, and some tools can perform special lossless operations. For a comparison of common web formats, see our guide to image formats.
A practical conversion workflow
- Check whether the destination format uses lossy or lossless compression and whether it supports the features you need, such as transparency.
- Work from the original file instead of a copy that has already been compressed.
- Choose settings for the intended use. Text, screenshots and sharp-edged graphics may need different settings from photographs.
- If you only need a smaller file, compare compression with resizing; resizing permanently changes pixel dimensions.
- Open the exported file at its intended viewing size and check text, edges, colors and any required details.
- Keep the original until you have confirmed that the exported file works.
Resizing is different from compression
Resizing changes the number of pixels. Reducing an image from 4,000 to 1,000 pixels wide removes spatial detail; enlarging it later cannot restore the original pixels. Compression changes how image data is stored, and lossy compression may discard information even when dimensions stay the same. Choose based on how the file will be viewed or printed.
Documents and repeated conversions
When exporting a document, use the original editor’s export function where possible. Printing and scanning can turn selectable text into an image and may reduce clarity. A PDF can also contain compressed images; inspect the export settings and keep an unchanged copy when signatures or other important content must be preserved.
Frequently asked questions
For a practical comparison of image formats, see the image format guide.
Frequently asked questions
Does converting JPEG to PNG restore lost detail?
No. PNG can preserve the decoded pixels from that point onward, but it cannot recover information already discarded by JPEG compression.
Does every second JPEG save reduce quality?
Not necessarily. It depends on whether the software re-encodes the image and which settings or lossless operations it uses. Keep the original and compare the output.
Is there one JPEG quality setting that is always best?
No. The visual result and file size depend on the image, encoder and intended use. Preview the result instead of relying on a universal number.