wp-includes/class-wp-image-editor-imagick.php:399Sets Image Compression quality on a 1-100% scale.
$qualityintoptionalnull$dimsarrayoptionalarray()true|WP_Error public function set_quality( $quality = null, $dims = array() ) { $quality_result = parent::set_quality( $quality, $dims ); if ( is_wp_error( $quality_result ) ) { return $quality_result; } else { $quality = $this->get_quality(); } try { switch ( $this->mime_type ) { case 'image/jpeg': $this->image->setImageCompressionQuality( $quality ); $this->image->setCompressionQuality( $quality ); $this->image->setImageCompression( imagick::COMPRESSION_JPEG ); break; case 'image/webp': $webp_info = wp_get_webp_info( $this->file ); if ( 'lossless' === $webp_info['type'] ) { // Use WebP lossless settings. $this->image->setImageCompressionQuality( 100 ); $this->image->setCompressionQuality( 100 ); $this->image->setOption( 'webp:lossless', 'true' ); parent::set_quality( 100 ); } else { $this->image->setImageCompressionQuality( $quality ); $this->image->setCompressionQuality( $quality ); } break; case 'image/avif': // Set the AVIF encoder to work faster, with minimal impact on image size. $this->image->setOption( 'heic:speed', 7 ); $this->image->setImageCompressionQuality( $quality ); $this->image->setCompressionQuality( $quality ); break; default: $this->image->setImageCompressionQuality( $quality ); $this->image->setCompressionQuality( $quality ); } } catch ( Exception $e ) { return new WP_Error( 'image_quality_error', $e->getMessage() ); } return true; }Introduced in 3.5.0. One change between 6.7.7 and 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
$dims added.verified against sourcesrc/wp-includes/class-wp-image-editor-imagick.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.