Find Where an Uploaded Image Became Blurry
Compare the original, your export and the delivered file to separate source blur, resizing, compression and display scaling.
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Keep three files or views for comparison
Start with the original, the exact file you uploaded and the version the destination displays. Compare the same small detail in all three. If it is already blurry in the original, changing the delivery format cannot recover the missing factual detail. If the export is clear but the delivered version is not, investigate the publishing path.
Do not assume every service recompresses every file. Some serve the original; others generate multiple sizes. Record the actual downloaded dimensions and bytes, or inspect the image resource in the browser, instead of diagnosing from the upload interface alone.
Separate a smaller file from a smaller pixel grid
If a proportional image changes from 6000 pixels wide to 1200, its width becomes one fifth of the original. Its total pixel count becomes one twenty-fifth, not one fifth. That calculation describes the grid only; it does not measure visual quality or predict the compressed file's bytes.
If the delivered width and height are unchanged but small text has developed ringing or blocks, lossy re-encoding is one possibility. Compare at the same display size. Different zoom levels can make one version appear sharper even before you examine its pixels.
Check how large the browser draws the image
A 400-pixel source displayed at 800 CSS pixels has to be enlarged. On a high-density display, even a source that matches the CSS width may look softer than a larger candidate. For an illustrative 300 CSS-pixel slot, compare 300- and 600-pixel exports rather than assuming one is sufficient.
A responsive site may also choose an undersized resource because its srcset or sizes information is inaccurate. Inspect the selected resource as well as the CSS box. TheImageIs upscaling tool uses browser resampling; making a small file larger does not verify or reconstruct the scene's missing details.
Change one stage and test again
Return to the original and export a candidate at the destination's recommended dimensions and an acceptable quality setting. Upload it as a test and compare the delivered copy. Preparing the file yourself gives you a controlled input, but does not prevent the destination from processing it again.
Check transfers between devices as well: a preview copied from a chat may differ from the original attachment. Compare actual files instead of assuming all email or messaging paths behave alike. Keep a short record of source dimensions, export settings and delivered dimensions so the next correction targets the stage that changed.
Trace a visible detail across the upload path
A guided exercise, not a benchmark. Inspect your own output; results depend on the source and settings.
- Preserve the original and the exact uploaded export as separate files.
- Download or inspect the actual delivered resource and record its dimensions and bytes.
- Compare the same detail at equal display size in all three versions.
- Change one factor in a new export, upload a test and repeat the comparison.
You can identify whether the detail was lost in the source, export, transfer, destination processing or display scaling.
Sources & further reading
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