Sharpen increases perceived sharpness by enhancing edges (high-frequency details).
It’s useful for correcting images that look soft after resizing, or making text/logos look crisper.
sharpen
Description
Sets the sharpening strength (sigma).
Higher values produce a stronger sharpening effect, but depending on the image, it may also increase noise/grain.
Format
?sharpen={sigma}
Supported range
0.3 ~ 20
Examples
Request
Result
?sharpen=1.2
Apply light sharpening
?sharpen=3
Apply stronger sharpening (may increase noise)
Using with other options
Applying sharpen after downscaling with width often helps reduce the slight softness introduced during resizing.
Recommended starting points
A good starting range is 1.0–1.5.
For logos/text, you’ll often notice a clear difference around ~2.0.
For photos with lots of smooth areas (skin, gradients), higher sharpening can look harsh or noisy—start low and increase gradually.
