How can I sharpen tiny thumbnails in Photoshop while keeping JPEG file size low?
Asked 11/15/2010
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2 answers
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I’m exporting very small thumbnails (about 120×80 px) for a photo app. Lightroom’s output sharpening for Screen/High looks best, but the JPEGs stay larger than I want, often around 25 KB. Photoshop’s Save for Web can hit my target size much more easily, but my current sharpening results don’t look as good.
In Photoshop I’m resizing to 120×80 with Bicubic Sharper and then applying Unsharp Mask, but I’m unsure what sharpening approach works best for thumbnails. What sharpening settings or techniques work well for very small web thumbnails without causing obvious halos or bloating JPEG size?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
15y ago
2 Answers
2
I find LR's output sharpening better than any techniques and settings I tried from PS:
- various unsharp mask settings (including the 2 mentioned here)
- sharpen > fade sharpen
- high pass sharpening
- Photokit's Output Sharpening
Nothing beats my LR output sharpening with "Sharpen for Screen High"
I have found out how to get them small.
- Update LR to 3.2, this will improve LR's "Limit File Size To".
I used 20KB as target. - The last thing was quite a surprise for me.
In LR I selected "Minimize Metadata" about the same as PS' > save for web > oprimized setting. LR seems to minimize.. not so minimal.
So I had a look with Exiftool and there was still a bunch of metadata. When I deleted all metadata with Exiftool I shaved of 10KB!
Off course by doing this command you will deleted also your ICC profile, copyrights etc, but you can also delete or add anything you want. A command line I use (and converted into an service on OSX, so it's accessible from finder's context menu) is:
_
/* delete all exit data except for the ICC Profile, add copyright, overwrite the original */
exiftool -all= --icc_profile:all -copyright='your copyright, name, website ect. here' -overwrite_original newfile.jpg
All images resized from 3000x2000 to 120x80 in Photoshop > Save for the Web, quality 75, optimized
No Sharpening: (12KB)
http://immoshots.com/test/thumbnail-sharpening/_DSC5068-PS-SafeForWeb-NoSharp.jpg
Unsharp Mask, amount 300%, radius 0.2, threshold 0 (16KB)
http://immoshots.com/test/thumbnail-sharpening/_DSC5068-PS-unsharp-300-0.2-0.jpg
Sharpen > Fade 50% (16KB)
http://immoshots.com/test/thumbnail-sharpening/_DSC5068-PS-sharpen-fade-50.jpg
Highpass technique (16KB)
http://immoshots.com/test/thumbnail-sharpening/_DSC5068-PS-HighPass-0.9.jpg
and finally LR + exiftool (8KB)
LR, limit file size: 20KB, sharpen for screen High
http://immoshots.com/test/thumbnail-sharpening/_DSC5068-LR.jpg
Look at the blue stripe above the waterline, the greens, the diagonal lines running up the mast.
Just for reference I have a higher res of the example.
Originally by user2181. Source · Licensed CC BY-SA 4.0
user2181
15y ago
0
Generated from our catalog & community — verify before relying on it.
For thumbnails this small, simple sharpening usually works better than more elaborate techniques. Community experience here suggests Unsharp Mask is enough; high-pass, smart sharpen, and plug-ins are generally overkill at 120×80.
A good approach in Photoshop is:
- resize first
- apply Unsharp Mask with a very small radius
- export with Save for Web at moderate JPEG quality
Settings that worked well in the answers were:
- Amount 300%, Radius 0.2, Threshold 0
- or Amount 50%, Radius 0.5, Threshold 2
The key is the small radius: after downsampling, thumbnails contain fine detail, so a tiny radius sharpens without creating strong halos. Stronger sharpening can also increase JPEG size, because extra high-frequency detail compresses less efficiently.
If file size is the priority, try slightly reducing sharpening strength and use Save for Web with moderate JPEG quality. Also strip metadata, since embedded metadata can add surprisingly large overhead on tiny files. Lightroom may retain more metadata than expected; removing all metadata can save significant space, though doing so may also remove the ICC profile.
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