Quick answer
To compare JPEG image results, keep input, format and settings fixed and change one variable. JPEG suits photos and gradients, compresses well but has no transparency; repeated saves accumulate loss.
Why it matters
Changing several variables at once makes results unattributable.
Quality 80-85% is usually enough for the web.
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
- Quality 80-85% is usually enough for the web.
- Transparent backgrounds need PNG/WebP.
FAQ
How do I compare two JPEG image results?
To compare JPEG image results, keep input, format and settings fixed and change one variable. JPEG suits photos and gradients, compresses well but has no transparency; repeated saves accumulate loss.
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 JPEG