Changeset 60246 for trunk/src/wp-includes/class-wp-image-editor-imagick.php

Timestamp:

05/22/2025 09:38:22 PM (15 months ago)

Author:

adamsilverstein

Message:

Media: fix degraded handling for 24 bit PNG uploads.

Add additional logic to correctly identify indexed PNG images so output PNGs correctly match the uploaded image depth.

Fix a regression introduced in WordPress 6.8 [59589] where uploaded Truecolor PNG images (meaning > 8 bit) were mis-identified as indexed (8 bit) images, causing output images to be indexed instead of Truecolor resulting in a noticeable visual degradation.

Props elvismdev, wildworks, SirLouen, siliconforks, joemcgill, iamshashank, nosilver4u.
Fixes #63448.

File:

• trunk/src/wp-includes/class-wp-image-editor-imagick.php (modified) (1 diff)

trunk/src/wp-includes/class-wp-image-editor-imagick.php

@@ -485 +485 @@
                                 $this->image->setOption( 'png:compression-level', '9' );
                                 $this->image->setOption( 'png:compression-strategy', '1' );
-                                // Check to see if a PNG is indexed, and find the pixel depth.
-                                if ( is_callable( array( $this->image, 'getImageDepth' ) ) ) {
-                                        $indexed_pixel_depth = $this->image->getImageDepth();
-
-                                        // Indexed PNG files get some additional handling.
-                                        if ( 0 < $indexed_pixel_depth && 8 >= $indexed_pixel_depth ) {
-                                                // Check for an alpha channel.
-                                                if (
-                                                        is_callable( array( $this->image, 'getImageAlphaChannel' ) )
-                                                        && $this->image->getImageAlphaChannel()
-                                                ) {
-                                                        $this->image->setOption( 'png:include-chunk', 'tRNS' );
-                                                } else {
-                                                        $this->image->setOption( 'png:exclude-chunk', 'all' );
-                                                }
-
-                                                // Reduce colors in the images to maximum needed, using the global colorspace.
-                                                $max_colors = pow( 2, $indexed_pixel_depth );
-                                                if ( is_callable( array( $this->image, 'getImageColors' ) ) ) {
-                                                        $current_colors = $this->image->getImageColors();
-                                                        $max_colors     = min( $max_colors, $current_colors );
-                                                }
-                                                $this->image->quantizeImage( $max_colors, $this->image->getColorspace(), 0, false, false );
-
-                                                /**
-                                                 * If the colorspace is 'gray', use the png8 format to ensure it stays indexed.
-                                                 */
-                                                if ( Imagick::COLORSPACE_GRAY === $this->image->getImageColorspace() ) {
-                                                        $this->image->setOption( 'png:format', 'png8' );
-                                                }
+
+                                // Indexed PNG files get some additional handling.
+                                // See #63448 for details.
+                                if (
+                                        is_callable( array( $this->image, 'getImageProperty' ) )
+                                        && '3' === $this->image->getImageProperty( 'png:IHDR.color-type-orig' )
+                                ) {
+
+                                        // Check for an alpha channel.
+                                        if (
+                                                is_callable( array( $this->image, 'getImageAlphaChannel' ) )
+                                                && $this->image->getImageAlphaChannel()
+                                        ) {
+                                                $this->image->setOption( 'png:include-chunk', 'tRNS' );
+                                        } else {
+                                                $this->image->setOption( 'png:exclude-chunk', 'all' );
                                         }
+                                        // Set the image format to Indexed PNG.
+                                        $this->image->setOption( 'png:format', 'png8' );
+
+                                } else {
+                                        $this->image->setOption( 'png:exclude-chunk', 'all' );
                                 }
                         }