What does the strength value actually control?

It scales the sharpening kernel's contrast boost. 0 leaves the frame unchanged, 100 applies the classic unsharp-mask kernel, and values up to 200 push the effect further, amplifying edge contrast more aggressively.

Will sharpening fix a blurry or low-resolution source GIF?

It can improve perceived crispness by boosting local contrast at edges, but it can't recover detail that was never captured. Very blurry or low-resolution sources will still look soft, just with harder edges.

Does sharpening affect transparency?

No, only the RGB channels are sharpened; each pixel's alpha channel is left untouched, matching the underlying PNG sharpener's behavior.

Can sharpening introduce visible artifacts?

Yes, at high strengths it can produce visible haloing around high-contrast edges, the same known tradeoff as any unsharp-mask filter.

GIF Sharpener - Unsharp Mask Every Frame

Overview

Introduction

GIFs re-encoded through lossy pipelines or downscaled from a larger source can look slightly soft. This tool boosts edge contrast on every frame to make the animation read as crisper.

The sharpening runs entirely client-side, frame by frame, before the animation is handed back to you as a new GIF.

What Is GIF Sharpener?

A per-frame unsharp-mask sharpening filter for animated GIFs: each frame is independently sharpened using the same 3x3 "plus" convolution kernel this codebase's PNG sharpener applies to static images.

The kernel boosts each pixel relative to its four orthogonal neighbors, amplifying local contrast at edges without needing a full 2D Gaussian-difference pass.

How GIF Sharpener Works

The GIF is decoded into fully composited RGBA frames. Each frame is passed through the shared `sharpenPng` function independently, so no information is carried over between frames.

The sharpened frames are then re-encoded into a new GIF, preserving the original frame delays and loop count.

When To Use GIF Sharpener

Use it when a GIF looks slightly soft after resizing, screen-capturing, or a previous lossy conversion.

Use it to make fine on-screen text or UI details in a recorded GIF read more clearly.

Often used alongside GIF Blurrer, GIF Pixelator and GIF Frame Cross-Fader.

Features

Advantages

Consistent sharpening strength across every frame, since each is processed independently and identically.
Reuses this codebase's already-tested unsharp-mask implementation rather than a new, unverified algorithm.
A single 0-200 strength control makes the effect easy to dial in.

Limitations

Can't recover detail that was never present in the source; it only boosts existing edge contrast.
High strengths can introduce visible haloing artifacts around high-contrast edges.
There's no region option; the whole frame is sharpened uniformly.

Examples

Sharpening a slightly soft screen recording

Input

A 10-frame GIF, sharpen amount 120

Output

The same 10 frames, each independently sharpened with a slightly-stronger-than-classic unsharp kernel, re-encoded with the same timing.

Every frame is sharpened on its own with amount 120 (above the classic k=1 amount of 100); the animation's timing and loop behavior are unchanged.

Best Practices & Notes

Best Practices

Start near 100 (the classic unsharp-mask strength) and adjust up or down from there.
If haloing appears around edges, reduce the strength rather than trying to counteract it with blur.
Sharpening after resizing, rather than before, usually gives a crisper final result.

Developer Notes

This tool calls the PNG category's exported `sharpenPng(image, amount)` once per decoded frame rather than reimplementing the unsharp kernel, keeping the sharpening math defined in exactly one place across both categories.

GIF Sharpener Use Cases

Crisping up on-screen text or UI details in a recorded tutorial GIF
Restoring some perceived detail after a GIF has been resized down
Giving a slightly soft animated graphic a punchier, higher-contrast look

Common Mistakes

Pushing the strength far past 100 and introducing visible edge haloing.
Expecting sharpening to fix genuinely low-resolution or heavily compressed source material.

Tips

If the result looks too harsh, back the strength down in increments of 20-30 rather than large jumps.
Pair with the GIF Blurrer at a very low radius first if the source has noisy compression artifacts that sharpening would otherwise amplify.

GIF Sharpener