Options

Pixel’s Settings page has three sections: Output and Canvas, described here, and Fonts. AI provider keys are not among them: they live in the global settings, see Assistant. Each section saves on its own: its Discard and Save sit in the section’s header.

Output

Output applies to every image on the site. Pixel stores it in the sleek-pixel_settings option, which the SettingsOperations_saveOptions operation and wp sleek pixel settings set write.

File format

The format of every rendered file: PNG (the default), JPEG or WebP. Facebook and X generally expect PNG or JPEG for og:image; a WebP image may not show in their previews. After a change, each image renders again in the new format on its next request, and its earlier file is deleted.

Image processing

How an image that has no rendered file yet is produced for a signed-in user:

• Synchronous (the default) renders the file during the request that needs it, so the image is there on the first view at the cost of a slower response for that one request.
• Asynchronous queues the file and renders it in a background request after the page is sent. A REST response and a feed render at once even then, because no later view would show them the image.

A visitor who is not signed in never waits for a render, whatever this setting says: their request queues the file like Asynchronous does, so no visitor can make the site render. While a file is queued, Pixel uses the image’s last rendered file for the same post and use, from before the design or Pixel changed. When there is none it leaves the page’s existing Open Graph and Twitter Card tags and its featured image untouched, and its PHP functions and shortcode return nothing. A file is queued once: later requests wait for that render, and queue it again only when it has not finished within ten minutes.

The background render runs on the site it was queued on, also when a network’s sites share the queue, in the language the page was requested in and with the page values the page had.

The block editor sidebar panel, WP-CLI, wp sleek pixel render and cron jobs always render synchronously, whatever this setting says.

Canvas

Canvas holds editor preferences. They belong to the signed-in user, not the site, so every administrator keeps their own; the User_read and User_save operations serve them.

From the command line

wp sleek pixel settings get prints the Output settings and wp sleek pixel settings set changes them, for example --imageProcessing=async. The CLI reference has their arguments.