# Recompress WebP (recompress_webp)

WebP-specific recompression. How the mod_pagespeed recompress_webp filter works, when to use it, its risks and the Apache, nginx and IIS directives.

Canonical URL: https://modpagespeed.com/docs/filters/recompress_webp/

- Category: Image
- CoreFilters: Yes
- OptimizeForBandwidth: Yes
- Risk: Generally safe

`recompress_webp` re-encodes WebP images the page already serves, at `WebpRecompressionQuality` (default 80). It does not create WebP; converting JPEG or PNG sources to WebP is the conversion filters' job. Animated WebP is never recompressed, and there is no fallback conversion of WebP to JPEG for browsers without WebP support: such sources are left alone rather than transcoded.

## How it works

The recompression filters reduce image file size by re-encoding images at an optimal quality level. They preserve visual quality while removing encoding inefficiencies, and each one handles exactly the format its name says, so a format you do not want re-encoded can be turned off by name without touching the others.

### How each format is recompressed

`recompress_webp` keeps a re-encode only when it is smaller under `ImageLimitOptimizedPercent`, and a losing result is remembered. A small-screen client gets a lower quality still: `WebpRecompressionQualityForSmallScreens` (default 70) applies to the requests the module classifies as small-screen. The filter is a CoreFilter through `rewrite_images` and part of OptimizeForBandwidth.

`recompress_images` is a convenience filter that enables `recompress_jpeg`, `recompress_png`, and `recompress_webp` together with `convert_gif_to_png`, `convert_jpeg_to_progressive`, `convert_jpeg_to_webp`, `convert_png_to_jpeg`, `jpeg_subsampling`, `strip_image_color_profile`, and `strip_image_meta_data`.

## When to use it

- In CoreFilters, the default RewriteLevel: it runs unless you disable it.
- Part of OptimizeForBandwidth, the level that optimizes resources without changing their URLs.
- Also switched on by [`recompress_images`](https://modpagespeed.com/docs/filters/recompress_images/) and [`rewrite_images`](https://modpagespeed.com/docs/filters/rewrite_images/).
- Risk rating on these docs: **Generally safe**.

## Risks

Recompression is lossy. Setting quality too low produces visible artifacts. The default values are conservative and safe for most content. Photographic content can tolerate lower quality than screenshots or text-heavy images.

## Configuration

Enable it in the module configuration, at server, virtual-host or location scope:

**Apache**

```apache
ModPagespeedEnableFilters recompress_webp
```

**nginx**

```nginx
pagespeed EnableFilters recompress_webp;
```

**IIS (pagespeed.config)**

```text
pagespeed EnableFilters recompress_webp
```

It is on by default under CoreFilters; to turn it off:

```text
ModPagespeedDisableFilters recompress_webp   # Apache
pagespeed DisableFilters recompress_webp;   # nginx
pagespeed DisableFilters recompress_webp   # IIS
```

| Parameter                   | Default | Description                                                                       |
| --------------------------- | ------- | --------------------------------------------------------------------------------- |
| `ImageRecompressionQuality` | 85      | General quality level for recompressed images (-1 to 100; -1 uses source quality) |
| `JpegRecompressionQuality`  | -1      | JPEG-specific quality; -1 uses `ImageRecompressionQuality`                        |
| `WebpRecompressionQuality`  | 80      | WebP quality level                                                                |

### On the worker

The worker runs its own pipeline, configured by flags. Its equivalent of this filter is the [image pipeline](https://modpagespeed.com/docs/worker-configuration/#image-pipeline) transform. Always-on baseline under `pagespeed on;`; there is no per-transform off switch.

Scoping, `ForbidFilters` and the thresholds filters read: [Choosing filters](https://modpagespeed.com/docs/filter-selection/).

## Frequently asked questions

**What does the recompress_webp filter do?**

`recompress_webp` re-encodes WebP images the page already serves, at `WebpRecompressionQuality` (default 80). It does not create WebP; converting JPEG or PNG sources to WebP is the conversion filters' job. Animated WebP is never recompressed, and there is no fallback conversion of WebP to JPEG for browsers without WebP support: such sources are left alone rather than transcoded.

**Is recompress_webp enabled by default?**

Yes. `recompress_webp` is in CoreFilters, the default RewriteLevel, so it runs unless you turn it off with `DisableFilters`. It is also part of the OptimizeForBandwidth level.

**How do I turn off recompress_webp?**

Add `ModPagespeedDisableFilters recompress_webp` on Apache or `pagespeed DisableFilters recompress_webp;` on nginx. On IIS, add `pagespeed DisableFilters recompress_webp` to pagespeed.config.

## Related filters

- [`recompress_images`](https://modpagespeed.com/docs/filters/recompress_images/): Recompress images
- [`recompress_jpeg`](https://modpagespeed.com/docs/filters/recompress_jpeg/): Recompress JPEG
- [`recompress_png`](https://modpagespeed.com/docs/filters/recompress_png/): Recompress PNG
- [`convert_gif_to_png`](https://modpagespeed.com/docs/filters/convert_gif_to_png/): Convert GIF to PNG
- [`convert_jpeg_to_avif`](https://modpagespeed.com/docs/filters/convert_jpeg_to_avif/): Convert JPEG to AVIF
- [`convert_jpeg_to_progressive`](https://modpagespeed.com/docs/filters/convert_jpeg_to_progressive/): Progressive JPEG
- [`convert_jpeg_to_webp`](https://modpagespeed.com/docs/filters/convert_jpeg_to_webp/): Convert JPEG to WebP
- [`convert_png_to_jpeg`](https://modpagespeed.com/docs/filters/convert_png_to_jpeg/): Convert PNG to JPEG

This page is drawn from the [recompress_webp entry on Image filters](https://modpagespeed.com/docs/image-filters/#recompress_webp). Every filter in one table: [PageSpeed filters](https://modpagespeed.com/docs/filters/).