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filter is not described

jpeg_quality filter-hook . WP 2.5.0

Filters the JPEG compression quality for backward-compatibility.

Applies only during initial editor instantiation, or when set_quality() is run manually without the $quality argument.

set_quality() has priority over the filter.

The filter is evaluated under two contexts: 'image_resize', and 'edit_image', (when a JPEG image is saved to file).

Usage

add_filter( 'jpeg_quality', 'filter_function_name_8912', 10, 2 );
function filter_function_name_8912( $quality, $context ){
	// filter...

	return $quality;
}
$quality(int)
Quality level between 0 (low) and 100 (high) of the JPEG.
$context(string)
Context of the filter.

Where the hook is called

WP_Image_Editor::set_quality()
wp_save_image_file()
wp-includes/class-wp-image-editor.php 257
$quality = apply_filters( 'jpeg_quality', $quality, 'image_resize' );
wp-admin/includes/image-edit.php 352
return imagejpeg( $image, $filename, apply_filters( 'jpeg_quality', 90, 'edit_image' ) );

Where the hook is used (in WP core)

Does not used.