Image compression troubleshooting: a step-by-step checklist

SlimPic guide · Updated October 4, 2026

Keep the original and test one affected image first. Match the symptom below instead of repeatedly applying the same settings.

The file never appears in the list

1. Check that it is JPG, PNG, or WebP. HEIC, HEIF, GIF, and PDF are unsupported. Renaming a file does not convert it.
2. Check the limits: 50MB per file, 20 files, 200MB total, 80 megapixels, and 32,768px on an edge.
3. Open it in another image viewer. If that also fails, the source may be damaged or only partly downloaded.

Text or faces look blurry

A small target can require both quality and dimension reductions. Start again from the original and try 300KB instead of 100KB, for example, without exceeding your destination’s limit. Check the advanced width and height limits too. Inspect names, numbers, and faces in the downloaded file, not only the small preview. If no readable result fits the allowed size, ask the receiving service for another submission method.

A transparent background became white

JPEG cannot store transparency. Start again from the transparent original and explicitly select PNG or WebP. Converting the white-background JPEG to PNG will not restore transparency.

The file meets 500KB but the destination rejects it

1. Select the new download, not the original.
2. If JPEG is required, explicitly choose JPG. Auto output may be WebP.
3. Distinguish per-file limits from the combined attachment limit. Check actual bytes.
4. An exact 600×800px requirement is different from a maximum bounding box. SlimPic preserves aspect ratio and does not crop.
5. Filename rules and destination errors cannot be fixed by compression.

Processing stops or the tab closes

Decoded pixels can require much more memory than the stored file. Try one image at a time and close unnecessary tabs. Switching apps or locking the screen may pause processing. Reloading, closing the page, or confirming a language change clears selected photos and results. Download completed results first.

The download is not in my photo library

Check the browser’s download list and the Files or Downloads folder. Extract a ZIP before viewing its images. Adding files to a photo library depends on your device and browser; SlimPic does not write to the library automatically.

Still stuck?

Contact us with your browser and device, source format and size, target size, and error text. Do not send ID documents or private originals. If possible, check whether a non-private sample reproduces the issue.