Is responsive_images_zoom enabled by default?

No. responsive_images_zoom is not in CoreFilters, the default RewriteLevel; it runs only when you enable it by name with EnableFilters.

How do I enable responsive_images_zoom on Apache and nginx?

Add ModPagespeedEnableFilters responsive_images_zoom on Apache or pagespeed EnableFilters responsive_images_zoom; on nginx. On IIS, add pagespeed EnableFilters responsive_images_zoom to pagespeed.config.

filter · Image filters

Responsive images zoom (responsive_images_zoom)

Q: What does the responsive_images_zoom filter do?

responsive_images_zoom adds a small script next to the srcset attributes that responsive_images generates, so that when the visitor zooms the page the browser picks a variant that stays sharp at the zoomed size instead of upscaling the one chosen for the original zoom level. Enable it together with responsive_images; on its own it does nothing. Not a core filter; test it with your image markup first.

Category:: Image
CoreFilters:: No
OptimizeForBandwidth:: No
Risk:: Not rated

responsive_images_zoom adds a small script next to the srcset attributes that responsive_images generates, so that when the visitor zooms the page the browser picks a variant that stays sharp at the zoomed size instead of upscaling the one chosen for the original zoom level. Enable it together with responsive_images; on its own it does nothing. Not a core filter; test it with your image markup first.

When to use it

Not in CoreFilters: it runs only when you enable it by name.

Risks

Adds a script to every page with responsive images.
Extra variants are fetched on zoom, which costs bandwidth on pages visitors zoom often.

Configuration

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

Apache

ModPagespeedEnableFilters responsive_images_zoom

nginx

pagespeed EnableFilters responsive_images_zoom;

IIS (pagespeed.config)

pagespeed EnableFilters responsive_images_zoom

ModPagespeedEnableFilters responsive_images,responsive_images_zoom

pagespeed EnableFilters responsive_images,responsive_images_zoom;

Scoping, ForbidFilters and the thresholds filters read: Choosing filters .

Frequently asked questions

What does the responsive_images_zoom filter do?: responsive_images_zoom adds a small script next to the srcset attributes that responsive_images generates, so that when the visitor zooms the page the browser picks a variant that stays sharp at the zoomed size instead of upscaling the one chosen for the original zoom level. Enable it together with responsive_images; on its own it does nothing. Not a core filter; test it with your image markup first.
Is responsive_images_zoom enabled by default?: No. responsive_images_zoom is not in CoreFilters, the default RewriteLevel; it runs only when you enable it by name with EnableFilters.
How do I enable responsive_images_zoom on Apache and nginx?: Add ModPagespeedEnableFilters responsive_images_zoom on Apache or pagespeed EnableFilters responsive_images_zoom; on nginx. On IIS, add pagespeed EnableFilters responsive_images_zoom to pagespeed.config.

convert_gif_to_png — Convert GIF to PNG
convert_jpeg_to_avif — Convert JPEG to AVIF
convert_jpeg_to_progressive — Progressive JPEG
convert_jpeg_to_webp — Convert JPEG to WebP
convert_png_to_jpeg — Convert PNG to JPEG
convert_to_avif_animated — Animated AVIF
convert_to_avif_lossless — Lossless AVIF
convert_to_webp_animated — Animated WebP

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