Image Sharpen FS

This is a small pixel-space sharpening node - the finishing kind you drop near the end of a graph when an image comes out a touch soft and you want to crisp up the edges without re-rendering. Nothing exotic: it takes an image, sharpens it, hands it back. What makes it slightly more interesting than a stock sharpen is that it lets you choose the character of the sharpening by picking which kind of blur it works against.

It's one of the image utilities bundled into RES4LYF (by ClownsharkBatwing), a pack whose headline act is flow-matching samplers and schedulers but which carries a few post-process helpers like this alongside them.

How it works

Sharpening, at heart, is "find the difference between the image and a blurred copy of it, then add that difference back to exaggerate edges." The choices here are about how that blurred copy is made. A median blur is edge-preserving and tends to sharpen without amplifying fine noise as much; a gaussian blur is the classic smooth kind and gives a more conventional unsharp-mask feel. The method switch (hard vs linear) changes how the sharpened result is blended back in. You don't need the math - just know that median-vs-gaussian and hard-vs-linear give you four flavors to taste-test on a given image.

The inputs and output

• images - the image (or batch) to sharpen. Pixel space, so after VAE Decode.
• type (default median) - the blur kernel behind the sharpen: median (edge-preserving, gentler on noise) or gaussian (classic unsharp feel).
• method (default hard) - how the effect is applied back: hard or linear. linear tends to read as the softer, more gradual of the two.
• intensity (default 6) - the strength. This is an integer and it climbs fast; 6 is already a firm sharpen, so if edges look crunchy or haloed, come down from there.

The single output is image - on to Save Image or whatever comes next.

Installing it

ComfyUI Manager: search RES4LYF, install, restart. Or manually: cd ComfyUI/custom_nodes && git clone https://github.com/ClownsharkBatwing/RES4LYF, then cd RES4LYF && pip install -r requirements.txt in your venv (portable ComfyUI uses the embedded pip). Restart, hard-refresh F5. No models to download.

Where people get burned

• Over-sharpening. intensity 6 is not subtle. Halos around high-contrast edges and a gritty, oversharpened look mean back it off. Sharpening is the last 5% of an image, not a fix for a blurry generation.
• Wrong order. Sharpen after upscaling and any grain/color work, right before saving. Sharpen early and a later resize undoes it or amplifies the artifacts.
• Fixing softness at the wrong layer. If the whole image is mushy, the problem is usually upstream - sampler, steps, or a soft upscaler. A sharpen pass papers over it; it doesn't add detail that was never rendered.
• Node won't load. It's the RES4LYF sharpen node; the pack must be installed for ComfyUI to find it.