Is convert_jpeg_to_webp enabled by default?

Yes. convert_jpeg_to_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 convert_jpeg_to_webp?

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

filter · Image filters

Convert JPEG to WebP (convert_jpeg_to_webp)

Q: What does the convert_jpeg_to_webp filter do?

convert_jpeg_to_webp serves WebP versions of JPEG images to browsers that send Accept: image/webp. The original JPEG is preserved for other browsers.

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

convert_jpeg_to_webp serves WebP versions of JPEG images to browsers that send Accept: image/webp. The original JPEG is preserved for other browsers.

How it works

convert_jpeg_to_webp is the member of the family with the widest reach, because JPEG is where photographic weight usually sits. For a WebP-capable request, the filter encodes a WebP candidate at WebpRecompressionQuality (default 80) and keeps it when it is smaller than the original JPEG. WebP-capable requests (by Accept: image/webp or a known user agent) get HTML pointing at a .webp URL; others get the JPEG URL, so the HTML differs per browser; a CDN caching rewritten HTML must not share it across browsers. The filter runs in CoreFilters through rewrite_images and is listed in OptimizeForBandwidth, but in that level’s in-place mode no WebP is selected.

convert_png_to_jpeg turns a PNG into a JPEG only when the module’s image analysis says the file is photographic, meaning not sensitive to compression noise, and it has no transparent pixels. The analysis is what protects flat graphics: a logo or a diagram analyzes as non-photographic and keeps its PNG. On a photographic PNG without transparency the filter authorizes lossy encoding, and the format that ships depends on the browser: when the request prefers WebP and convert_jpeg_to_webp is on, the file becomes WebP rather than JPEG; otherwise it is re-encoded as JPEG at the JPEG quality setting. A PNG with transparency is never made a JPEG. The converted file is kept only when it is smaller (ImageLimitOptimizedPercent), and a PNG carrying a C2PA content-credentials manifest is left untouched so its provenance chain survives. The filter runs in CoreFilters through rewrite_images.

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 and rewrite_images.
Risk rating on these docs: Generally safe.

Risks

convert_jpeg_to_webp decides per request, so the rewritten HTML names a .webp image for some browsers and a JPEG for others. A CDN or proxy that caches the HTML must not serve one browser’s copy to another; test with your CDN configuration.

Configuration

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

Apache

ModPagespeedEnableFilters convert_jpeg_to_webp

nginx

pagespeed EnableFilters convert_jpeg_to_webp;

IIS (pagespeed.config)

pagespeed EnableFilters convert_jpeg_to_webp

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

ModPagespeedDisableFilters convert_jpeg_to_webp   # Apache
pagespeed DisableFilters convert_jpeg_to_webp;   # nginx
pagespeed DisableFilters convert_jpeg_to_webp   # IIS

Parameter	Default	Description
`ProgressiveJpegMinBytes`	10240	Minimum JPEG size before converting to progressive
`WebpRecompressionQuality`	80	Quality for lossy WebP conversion
`WebpAnimatedRecompressionQuality`	70	Quality for animated WebP conversion

On the worker

The worker runs its own pipeline, configured by flags. Its equivalent of this filter is the 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 .

Frequently asked questions

What does the convert_jpeg_to_webp filter do?: convert_jpeg_to_webp serves WebP versions of JPEG images to browsers that send Accept: image/webp. The original JPEG is preserved for other browsers.
Is convert_jpeg_to_webp enabled by default?: Yes. convert_jpeg_to_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 convert_jpeg_to_webp?: Add ModPagespeedDisableFilters convert_jpeg_to_webp on Apache or pagespeed DisableFilters convert_jpeg_to_webp; on nginx. On IIS, add pagespeed DisableFilters convert_jpeg_to_webp to pagespeed.config.

convert_jpeg_to_avif — Convert JPEG to AVIF
rewrite_images — Optimize images
recompress_jpeg — Recompress JPEG
convert_gif_to_png — Convert GIF to PNG
convert_jpeg_to_progressive — Progressive JPEG
convert_png_to_jpeg — Convert PNG to JPEG
convert_to_webp_animated — Animated WebP
convert_to_webp_lossless — Lossless WebP

This page is drawn from the convert_jpeg_to_webp entry on Image filters. Every filter in one table: PageSpeed filters.