Online Image Sharpen Tool
Enhance image edges and local details. Processing takes place locally in your browser.
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What Online Image Sharpen Tool actually does
Sharpens one image with a selectable 3 by 3 or 5 by 5 convolution mask. The 3 by 3 mask is selected initially and Intensity ranges from 0% to 100%, default 25%.
Checkable example
At 0% the original pixels are retained; at 100% the complete kernel result is used. Higher strength or the larger mask can emphasize halos, sensor noise and compression blocks, and clipped channel values cannot be recovered.
Controls, output and limits
The 3 by 3 kernel is [0,-1,0; -1,5,-1; 0,-1,0]. The 5 by 5 option uses center weight 17 with surrounding -1 and -2 weights. Filtered RGB is blended with the original by strength/100 and alpha is preserved.
The tool accepts one browser-decodable image no larger than 25 MiB (26214400 bytes) and 24,000,000 decoded pixels. Output dimensions stay unchanged and the PNG download uses -sharpen in its filename; source format, metadata and animation are not kept.
Generate with the default 3 by 3 mask first and inspect edges at full size before increasing strength. This is browser-local convolution, not AI restoration, deblurring, upscaling or recovery of detail absent from the source.
Choose one 3×3 or 5×5 mask; default 3×3. The linked slider and number field accept 0–100%, default 25%, with displayed step 0.01. RGB convolution is first clamped to 0–255 and rounded to a byte, then blended with the source and rounded again. For one channel with center 100 and four adjacent values 0, the 3×3 sum 500 becomes 255; at 50% the result is 178.
Changing strength or mask clears the result, disables download and cancels an unfinished task. Generate again, inspect, then download separately. Loading a new image or clearing also cancels the old task. Clear removes the images but retains strength and mask.
One browser-readable image must meet both limits: 25 MiB (26214400 bytes) and 24000000 decoded pixels. Output is a static PNG with the same dimensions and preserved alpha. Strength 0 is neutral for the decoded pixels, not a byte-identical copy of the original file. Animation and original metadata are not retained.
Processing takes place locally in your browser.