WP_Image_Editor_GD::load

	public function load() {
		if ( $this->image ) {
			return true;
		}

		if ( ! is_file( $this->file ) && ! preg_match( '|^https?://|', $this->file ) ) {
			return new WP_Error( 'error_loading_image', __( 'File doesn’t exist?' ), $this->file );
		}

		// Set artificially high because GD uses uncompressed images in memory.
		wp_raise_memory_limit( 'image' );

		$this->image = @imagecreatefromstring( file_get_contents( $this->file ) );

		if ( ! is_resource( $this->image ) ) {
			return new WP_Error( 'invalid_image', __( 'File is not an image.' ), $this->file );
		}

		$size = @getimagesize( $this->file );
		if ( ! $size ) {
			return new WP_Error( 'invalid_image', __( 'Could not read image size.' ), $this->file );
		}

		if ( function_exists( 'imagealphablending' ) && function_exists( 'imagesavealpha' ) ) {
			imagealphablending( $this->image, false );
			imagesavealpha( $this->image, true );
		}

		$this->update_size( $size[0], $size[1] );
		$this->mime_type = $size['mime'];

		return $this->set_quality();
	}