Online Image Edge Enhancement Tool

What Online Image Edge Enhancement Tool actually does

Sharpens one image with a convolution-mask choice: 3 by 3 is selected by default or 5 by 5. There is no strength slider, threshold, selective mask or per-channel option; the chosen fixed kernel is applied to the complete decoded image.

Checkable example

Verified example: in a uniform grayscale image of 100 with a center value 110, the 3 by 3 mask changes that center to 150 while the 5 by 5 mask changes it to 230. The larger mask can therefore create stronger local contrast and clip bright or dark detail sooner.

Controls, output and limits

The 3 by 3 kernel is [0,-1,0;-1,5,-1;0,-1,0]. The 5 by 5 kernel has center weight 13 and subtracts 12 axial and surrounding neighbors. RGB channels are processed independently, edge samples repeat the nearest source pixel, results clamp to 0..255 and alpha remains unchanged.

Input is one browser-decodable image up to 25 MiB (26 214 400 B) and 24,000,000 pixels. Output dimensions match the source. Press Generate after choosing the mask, inspect the preview and download a PNG named from the source base plus -edgeEnhance.png; no original-format output is offered.

This is fixed spatial sharpening, not AI enhancement, deblurring, super-resolution or restoration of detail absent from the source. It can amplify noise, compression blocks and halos, especially with 5 by 5, so preserve the original and compare at actual display size.