Probed by encoding a test swatch and checking the MIME type the browser put on the result. Browsers fall back to PNG without saying so when they can’t encode a type, so an unprobed “AVIF” button hands you a PNG with the wrong extension. Anything marked no is switched off above rather than faked.
Downscaling runs as successive halving rather than one jump, because a single draw from 4000 px to 400 px samples about one source pixel in a hundred and aliases badly on fine detail.
- Every conversion here is a re-encode. The image is decoded to raw pixels and encoded again. There is no way to transcode losslessly between these formats in a browser canvas.
- Metadata does not survive. The canvas hands the encoder pixels only, so EXIF (camera, lens, GPS, timestamps), the ICC colour profile and the orientation tag are all gone from the output. Losing the ICC profile matters: a Display-P3 or Adobe RGB source will be re-tagged as sRGB, so saturated colours can shift visibly.
- Orientation is applied, not dropped. The EXIF rotation is read from the JPEG’s APP1 segment and baked into the pixels, so phone photos come out upright instead of sideways.
- PNG output is not optimised. The browser’s PNG encoder does none of the palette reduction or filter search that
pngquantoroxipngdo, so PNG → PNG is frequently larger than what you started with. When that happens it is stated below, not hidden. - Nothing is uploaded. No server, no API key, no telemetry on your files — the work happens in this tab and the bytes never leave it.
About Image Converter
Convert images between PNG, JPEG and WebP with resizing and quality control, plus a plain account of what each re-encode actually costs.
What it does
Drop in one image or a batch, choose an output format, set dimensions and quality, and download the result. Conversion runs on a canvas in your browser, so even large photographs never get uploaded anywhere.
What re-encoding costs
JPEG is lossy, and every save discards a little more detail — converting JPEG to JPEG is generational loss, not a neutral operation. Going from JPEG to PNG will not restore what the first encode threw away; it just stores the damaged pixels losslessly, usually in a much bigger file. Converting away from PNG discards transparency unless the target supports it, and re-encoding drops EXIF metadata, including the orientation flag that tells a viewer which way is up.
Common questions
- Will converting a JPEG to PNG improve its quality?
- No. The detail lost in the original JPEG encode is gone. PNG will store the existing pixels without further loss, but the file will usually be considerably larger for no visible gain.
- What happens to transparency?
- PNG and WebP keep an alpha channel. JPEG has none, so transparent areas are composited onto a background colour.
- Is EXIF data kept?
- No — re-encoding drops metadata, including GPS coordinates. That is often exactly what you want before sharing a photo, but it also means the orientation flag goes, so the tool applies rotation to the pixels themselves.
- Are my images uploaded?
- No. Everything happens in your browser — nothing you enter is uploaded, and the tool keeps working with no network connection.