🌀 Fast Laplacian Sharpen

If FastUnsharpSharpen is the polite one, FastLaplacianSharpen is the one that shows up with an electric guitar. It applies a Laplacian kernel - a second-derivative operator that lights up every high-frequency transition, not just edges - to extract detail, then adds it back scaled by strength. Because the Laplacian responds to all detail (including noise), this is the sharpener that can make AI video look dramatically crisper and dramatically worse, often in the same clip.

It's part of the VRGameDevGirl "Fast" sharpening trio, and the pack's own framing calls it "punchy" and good for "detail recovery." That's honest. Where unsharp masking gives you controlled edge contrast, Laplacian gives you that over-sharpened, high-contrast "detail is popping" look. It's the closest thing the pack has to a one-knob detail slider.

The inputs that matter

• images - your IMAGE frame tensor.
• strength - 0.0 to 2.0, default 0.5.
• use_gpu - off by default; flip on if CPU-bound and you have VRAM to spare.

Output: single IMAGE tensor, same shape, chainable with everything else.

Where it wins and where it bites

Use it for recovery: footage that came out of a fast generation looking flat and plastic, where you want every eyelash and thread of fabric back. At low strength (0.3–0.5) it genuinely restores perceived detail that soft encoders smoothed away. It pairs well after upscaling, where the upscaler has added resolution but not detail.

The trap is twofold. First, the Laplacian amplifies noise too - sharpen before film grain and you'll sharpen the noise; grain first, sharpen after, and you get clean detail. Second, over ~0.7 on video you'll see halos and that crunchy, oversharpened "looks like a cheap TV preset" effect. The classic beginner move is cranking strength to 1.5 expecting magic; you get halos. This is the sharpener where the default of 0.5 is genuinely the right place to start, and you should probably end lower than you think.

Install

Standard pack install:

cd ComfyUI/custom_nodes
git clone https://github.com/vrgamegirl19/comfyui-vrgamedevgirl

Or search vrgamedev in ComfyUI Manager, install, restart. No extra deps beyond torch.

Troubleshooting

• Halos / white edges around objects: too much strength. Drop it.
• Video looks noisy or shimmering: you're sharpening noise. Check your grain placement and lower strength; also consider whether the footage was already sharp and doesn't need this pass at all.
• "It did nothing": on already-soft, low-detail footage a Laplacian pass at 0.5 can be subtle. Compare a single frame before/after to see what it's actually doing before you push the dial.

Reach for unsharp for general fixes, Laplacian when you specifically want that aggressive detail-recovery punch and can keep the strength honest. It's the sharpener people blame for ruining video and it's usually the strength slider's fault, not the node's.