JPEG scan notes
The checker scans JPEG markers to identify common baseline and progressive encoding signals.
It is a publishing check for existing JPG files; the first version does not create progressive JPEG output.
Progressive JPEG Checker
Inspect a JPG file before publishing to see whether it uses baseline or progressive encoding and decide if compression or format conversion is useful.
Baseline or progressive checkJPEG marker scanFile detailsNo upload
Progressive JPEG checker
Result preview
Choose an image or enter dimensions to see results.
Choose an image or enter dimensions to see results.
How it works
- 1Choose a JPG or JPEG image.
- 2ImgShrink scans the JPEG structure in the browser.
- 3Review whether the file is baseline, progressive or unknown, then choose a next optimization step if needed.
Privacy and limits
- This first version checks JPEG encoding type; it does not create progressive JPEG output.
- Progressive JPEG is not always smaller or better for every workflow.
- The file is read locally and is not uploaded.
Common use cases
- Check a JPG before uploading it to a website
- Decide whether to recompress or convert a large JPG
- Document whether an image is baseline or progressive during QA
JPEG notes
- Baseline JPEG usually uses SOF0 markers.
- Progressive JPEG usually uses SOF2 markers.
- Some unusual or damaged files may return unknown.
Original test sample
- Upload a known progressive JPEG and confirm the result reports progressive.
- Upload a regular baseline JPG and confirm the result reports baseline.
Frequently asked questions
Are my images uploaded?
No. ImgShrink processes selected images in your browser and does not upload them to a server.
Can this tool guarantee an exact file size?
No. Target compression gets close when possible, but the final bytes depend on image detail, dimensions, format and browser encoding.
Why is an output format unavailable or different?
The browser controls image decoding and export support. Some browsers may not export AVIF or may flatten unsupported transparency.
Source and compatibility notes
This tool works in the browser, so output support depends on what your browser can read and export.
Last checked: 2026-09-07
Notes
- No server-side image processing is used.
- Output format support depends on the browser.
- Animated images and metadata are not treated as guaranteed preserved data.
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