WP_Image_Editor_GD::_save( resource $image, string|null $filename = null, string|null $mime_type = null )

	protected function _save( $image, $filename = null, $mime_type = null ) {
		list( $filename, $extension, $mime_type ) = $this->get_output_format( $filename, $mime_type );

		if ( ! $filename )
			$filename = $this->generate_filename( null, null, $extension );

		if ( 'image/gif' == $mime_type ) {
			if ( ! $this->make_image( $filename, 'imagegif', array( $image, $filename ) ) )
				return new WP_Error( 'image_save_error', __('Image Editor Save Failed') );
		}
		elseif ( 'image/png' == $mime_type ) {
			// convert from full colors to index colors, like original PNG.
			if ( function_exists('imageistruecolor') && ! imageistruecolor( $image ) )
				imagetruecolortopalette( $image, false, imagecolorstotal( $image ) );

			if ( ! $this->make_image( $filename, 'imagepng', array( $image, $filename ) ) )
				return new WP_Error( 'image_save_error', __('Image Editor Save Failed') );
		}
		elseif ( 'image/jpeg' == $mime_type ) {
			if ( ! $this->make_image( $filename, 'imagejpeg', array( $image, $filename, $this->get_quality() ) ) )
				return new WP_Error( 'image_save_error', __('Image Editor Save Failed') );
		}
		else {
			return new WP_Error( 'image_save_error', __('Image Editor Save Failed') );
		}

		// Set correct file permissions
		$stat = stat( dirname( $filename ) );
		$perms = $stat['mode'] & 0000666; //same permissions as parent folder, strip off the executable bits
		@ chmod( $filename, $perms );

		/**
		 * Filters the name of the saved image file.
		 *
		 * @since WP-2.6.0
		 *
		 * @param string $filename Name of the file.
		 */
		return array(
			'path'      => $filename,
			'file'      => wp_basename( apply_filters( 'image_make_intermediate_size', $filename ) ),
			'width'     => $this->size['width'],
			'height'    => $this->size['height'],
			'mime-type' => $mime_type,
		);
	}