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)
Unsharp Mask, amount 300%, radius 0.2, threshold 0 (16KB)
Sharpen > Fade 50% (16KB)
Highpass technique (16KB)
and finally LR + exiftool (8KB)
LR, limit file size: 20KB, sharpen for screen High
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.