Why won't my JPEG get smaller enough for web use?
Asked 9/10/2019
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2 answers
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I'm exporting film scans as JPEGs for my website, but even at very low JPEG quality in Photoshop, the files are still over 2 MB. For example, a 17.4 MB JPEG exported with Save for Web or Export As at around 20% quality still ends up about 2.6 MB. Why is there a limit to how much it will compress, and how can I get images closer to about 300 KB for web use without ruining them?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
6y ago
2 Answers
7
I do not know at which resolution you scanned your image, but i'm willing to bet that it is way larger than needed or useful for web viewing.
The first thing you should do is resize the image down to some useful dimensions. Think about how large it will be viewed and resize accordingly (keep in mind that currently a high end monitor resolution is 2560x1440).
Furthermore, your image might contain a lot of noise, which doesn't compress well. Running a denoising filter might reduce file size and even improve quality (careful there, don't make it look unnatural).
Originally by user32110. Source · Licensed CC BY-SA 4.0
user32110
6y ago
0
Generated from our catalog & community — verify before relying on it.
JPEG quality alone usually isn’t enough if the image dimensions are still very large. Your scans are likely much higher resolution than needed for web display, so the main fix is to resize the image first, then export it as JPEG.
Why this happens:
- JPEG compression has limits; some detail and noise don’t compress efficiently.
- Large images contain far more pixels than a website needs.
- Noise/grain can also keep file sizes higher.
What to do:
- Keep your original full-resolution scan.
- Make a web copy resized to the actual display size you need.
- As a rough guide, something around 2000 px on the long edge is already enough for most web uses, and often smaller is fine.
- Then export that resized version as JPEG at a moderate quality setting.
- If the scan is very noisy or grainy, light denoising may help reduce file size, but don’t overdo it.
In short: to reach ~300 KB, you’ll usually need fewer pixels, not just harsher compression.
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