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1Fix the driver behind crashes, sound loss and screen glitches2Clear out junk files and repair common Windows errors3Scan for outdated or missing drivers - takes under a minuteTo generate thumbnail images for WordPress pages, enable featured images in your theme, register an image size that fits your layout, assign a featured image to each page, and request the registered size in your template. If you add or change the size after images are already in the Media Library, regenerate those image files; changing theme code alone does not rebuild them.
What “thumbnail” means in WordPress
WordPress uses “Featured Image” and “Post Thumbnail” for the image that represents a page, post, or custom post type. A thumbnail can also mean a smaller, generated image file derived from an upload. Assigning a featured image chooses the source image for content; registering an image size tells WordPress what derivative to create and lets template code request it.
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The steps below cover both meanings: assigning an image to a page and generating and displaying a layout-sized derivative.
Enable featured images for pages
Your theme must support post thumbnails for the Featured Image control to appear in the editor. Add this to the theme’s setup code, commonly in functions.php or a file loaded by it:
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add_action( 'after_setup_theme', function () {
add_theme_support( 'post-thumbnails' );
} );If you want support limited to pages rather than all supported post types, you can scope it:
add_action( 'after_setup_theme', function () {
add_theme_support( 'post-thumbnails', array( 'page' ) );
} );Make theme changes in a child theme or another maintainable theme-code location so an update does not overwrite them. If your site uses a block theme or a page builder, check its documentation too: its editor controls and templates may differ from a classic theme’s.
Register an image size for the page layout
Choose dimensions and a crop that match the actual card, archive, or page layout where the image will appear. Register a named size during theme setup:
add_action( 'after_setup_theme', function () {
add_theme_support( 'post-thumbnails' );
add_image_size( 'page-card', 640, 360, true );
} );Here, page-card is the size name, and 640 by 360 defines a fixed frame. With the final argument set to true, WordPress crops to that frame, centered by default. The crop can instead specify horizontal and vertical positions:
add_image_size( 'page-card', 640, 360, array( 'center', 'top' ) );Use false for proportional scaling instead of a hard crop:
add_image_size( 'page-card', 640, 360, false );Proportional scaling preserves the image’s aspect ratio, so its resulting dimensions may not fill a fixed card frame. A hard crop fills the frame but cuts off parts of the source. Preview representative images in the real layout before settling on a crop, especially where faces, text, or logos need to stay visible.
WordPress has built-in image size names including thumbnail, medium, medium_large, large, full, and post-thumbnail. Use a custom name when the built-in sizes do not fit the layout, and use the same name when registering and requesting it.
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A free scan shows the junk files, broken settings and background clutter dragging Windows down - then fixes them in one click.Free scan · Windows 10 & 11Request the size in the page template
In the loop that renders pages, request the registered size by name:
the_post_thumbnail( 'page-card' );For example, a classic theme template can display each page’s featured image like this:
if ( have_posts() ) {
while ( have_posts() ) {
the_post();
the_post_thumbnail( 'page-card' );
the_title( '<h2>', '</h2>' );
}
}This function outputs the image for the current post in the loop. If a page has no featured image, it will not output one; add a fallback separately if the design requires a placeholder. Block themes and page builders may use different template controls, but the key requirement remains that the displayed image uses the intended registered size.
Assign a featured image to a page
- Open the page in the WordPress editor.
- In the editor sidebar, find the Featured Image control. If it is missing, confirm the theme has post-thumbnail support and that the page post type is supported.
- Select an existing Media Library image or upload one, then set it as the featured image.
- Update the page and check the relevant archive, card, or template to confirm the image and crop look right.
In some editor layouts, the sidebar may be hidden or the control may be unavailable because of theme or post-type configuration. Check the editor’s available panels and the active theme’s documentation before changing code or installing another plugin.
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Regenerate image sizes for existing uploads
Registering a new size affects image processing for new uploads. It does not create that derivative for images already in the Media Library. After adding or changing a size, regenerate the existing files with WP-CLI or an admin plugin.
WP-CLI
Run this from the WordPress installation directory in an environment where WP-CLI is configured:
wp media regenerateReview the command’s options in your installed WP-CLI version if you need to limit the operation rather than process the library broadly. Back up the site’s media files before a large regeneration job, and allow enough time and storage for it to finish.
Admin plugins
Simple Image Sizes describes controls for creating custom sizes and choosing which sizes to regenerate under Settings → Media; its plugin listing specifies PHP 8. reGenerate Thumbnails Advanced describes selective rebuilding, including featured images. Check each plugin’s current compatibility with your WordPress, PHP, and theme setup before using it, and back up media before bulk processing.
Choose the method that fits your access
| Method | Access needed | Useful when | Considerations |
|---|---|---|---|
| Theme code and template | Ability to edit or maintain theme code | You need a stable named size that matches the site’s layout | The size must be registered and requested consistently; changes do not rebuild existing files. |
| WP-CLI regeneration | Shell or hosting access with WP-CLI available | You want to regenerate existing derivatives from the site environment | Bulk work can take time; check command options and back up media first. |
| Admin plugin | WordPress administration access | You need a dashboard interface or selective regeneration controls | Compatibility depends on the plugin, WordPress, PHP, and theme versions; verify before a large job. |
Troubleshooting common problems
The Featured Image control is missing
- Confirm the active theme calls
add_theme_support( 'post-thumbnails' )during theme setup. - If support is scoped, confirm the
pagepost type is included. - Check whether the editor sidebar or relevant panel is hidden, and consult the theme or page-builder documentation.
The displayed image has the wrong dimensions or crop
- Confirm the template requests the intended registered name, such as
page-card, rather than a different built-in size. - Check that the crop argument matches the layout: proportional scaling preserves the full image, while hard cropping fills a frame and removes part of the source.
- Verify the rendered component’s actual aspect ratio before choosing dimensions; a theme or page builder may define its own image behavior.
A new size does not appear for older images
Existing uploads need regeneration after a size is registered or changed. Run wp media regenerate or use a compatible plugin to create the missing derivatives.
The page has no image
Registering a size does not assign a featured image. Set one in the page editor, or add template fallback behavior if the design should show an image when none is assigned.
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curl -G "https://api.screenshotneo.com/v1/shot" -d access_key=YOUR_API_KEY --data-urlencode url=https://example.com -o shot.webpSee the ScreenshotNeo API documentation for request options. It can remove cookie and consent banners, newsletter popups, and chat widgets before capture; bot checks, blank pages, and failed loads are not billed. Its MCP server lets AI agents take screenshots. The Free plan includes 1,000 screenshots a month with no card; paid plans start at $5 for 3,000.
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