Is this a Gaussian blur or a box blur?

It's a box blur: each pixel becomes the unweighted average of its neighbors within the chosen radius, applied as two passes (horizontal, then vertical) for speed. It's a close, fast approximation of a Gaussian blur rather than a true weighted Gaussian kernel.

Does the blur radius apply per frame or across the whole animation?

Per frame: each frame is blurred independently using its own pixels, so there's no motion-blur trail carried over between frames.

Will blurring change the GIF's colors?

Slightly. Averaging neighboring pixels can shift subtle color detail, and re-encoding then quantizes the result to this category's shared 216-color-plus-transparency palette.

Can I blur only part of a frame instead of the whole thing?

Not with this tool: it blurs the entire frame uniformly. For a region-only softening effect, use the GIF Pixelator or GIF Censor tool instead.

GIF Blurrer - Box Blur Every Frame

Overview

Introduction

A blur can soften harsh compression artifacts, de-emphasize a busy background, or create a dreamy visual effect, and this tool applies that effect consistently to every frame of an animated GIF.

The blur runs entirely in your browser, frame by frame, before the animation is re-encoded and handed back to you.

What Is GIF Blurrer?

A per-frame box blur for animated GIFs: each frame is independently blurred at a chosen radius using the same separable box-blur algorithm this codebase's PNG blurrer applies to static images.

Box blur averages each pixel with its neighbors within the radius in two passes (horizontal then vertical), a fast, simple approximation of a true Gaussian blur.

How GIF Blurrer Works

The GIF is decoded into fully composited RGBA frames. Each frame is passed through the shared `blurPng` box-blur function independently, so no information leaks between frames.

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

When To Use GIF Blurrer

Use it to soften a busy or distracting background across an animated clip.

Use it to reduce visible compression blockiness in a low-quality source GIF.

Often used alongside GIF Sharpener, GIF Pixelator and GIF Watermark Remover.

Features

Advantages

Consistent blur strength across every frame, since each is processed independently and identically.
Reuses this codebase's already-tested box-blur implementation rather than a new, unverified algorithm.
Simple, single radius parameter to control blur strength.

Limitations

Box blur is an approximation of Gaussian blur; it can leave faint square-ish artifacts at very large radii compared to a true weighted Gaussian kernel.
It can let a bit of color bleed through fully-transparent neighboring pixels near hard alpha edges, the same known limitation as the underlying PNG blurrer.
There's no region option; the whole frame is blurred uniformly.

Examples

Softening a screen-recording GIF

Input

A 15-frame screen-recording GIF, blur radius 3

Output

The same 15 frames, each independently box-blurred with radius 3, re-encoded with the same timing.

Every frame is blurred on its own; the animation's timing and loop behavior are unchanged.

Best Practices & Notes

Best Practices

Start with a small radius (2-4px) since box blur strength increases quickly with radius.
If you only need to soften a specific area, use the GIF Pixelator or GIF Censor tool's region option instead of blurring the whole frame.
Preview the result before committing to a very high radius, since detail loss at high radii is difficult to reverse.

Developer Notes

This tool calls the PNG category's exported `blurPng(image, radius)` once per decoded frame rather than reimplementing box blur, keeping the blur math defined in exactly one place across both categories.

GIF Blurrer Use Cases

Softening a busy or cluttered background behind an animated subject
Reducing visible blockiness in a low-quality re-encoded GIF
Creating a soft-focus, dreamy visual effect for a decorative animation

Common Mistakes

Setting the radius very high expecting a smooth Gaussian look; box blur at high radii can look boxier than a true Gaussian blur.
Blurring the whole frame when only a small region actually needed softening.

Tips

Combine with the GIF Sharpener afterward at a modest amount if the blur softened detail you still want to partially recover.
If edges near transparent regions look off, try a smaller radius.

GIF Blurrer