Quick answer
The most common Avatars and thumbnails mistakes are overwriting originals, ignoring format/quality and not checking the output. Avatars only need 256-512px; uploading the original is slow and wasteful.
Why it matters
These mistakes cause irreversible data or quality loss.
Crop square before resizing to avoid distortion.
Step by step
- Back up the original; never overwrite the only copy.
- Confirm the target platform's format, dimensions and size limit.
- Cap the longest side first, then quality; change one variable at a time.
- Compare size and sharpness after compressing, and step back one setting if needed.
- Keep the original until the output is confirmed.
Common mistakes
- Chasing the smallest file and blurring text/edges.
- Converting transparent PNG to JPEG, turning transparency white or black.
- Recompressing the same file and accumulating loss.
- Overwriting the original, so a bad result cannot be undone.
Checklist
- Original backed up.
- Output format/dimensions/size meet the platform.
- Text is readable and transparency is correct.
- Verified in the real page/email/upload field.
- Original kept until confirmed.
Key facts
- Crop square before resizing to avoid distortion.
- Use PNG/WebP for transparent avatars.
FAQ
What are common Avatars and thumbnails mistakes?
The most common Avatars and thumbnails mistakes are overwriting originals, ignoring format/quality and not checking the output. Avatars only need 256-512px; uploading the original is slow and wasteful.
How long does it take?
Usually 1-3 minutes; for intermittent issues, run 30 seconds and retest elsewhere.
Is data uploaded?
Runs locally and does not upload video/audio; extensions may still read the page.
Source: MDN Canvas