imagecolorstotal - PHP code example

PHP Function ImagecolorsTotal

php function imagecolorstotal is an inbuilt function in PHP which helps us to find the number of colors present in an images palette. It takes a GdImage resource as its parameter. The image is the resource returned by one of the image creation functions like imagecreatetruecolor ( ) or imagecreate( ).

Unlike a lot of other web scripting languages, PHP offers an inbuilt GD library that allows you to dynamically create and edit images as well as to output them directly to the browser. The GD Library is included with most PHP installations and can be enabled by running ?php echo phpinfo();?>.

Aside from working with images, PHP can also work with information stored in the headers of JPEG, PNG, svg and TIFF files. This can include the image type, image width and height, attributes, created date and last modified date. To access this metadata in PHP, you need to ensure that it has been compiled with --enable-exif and that mbstring has been enabled.

Getting an image's colors can be a daunting task for someone who is not familiar with the image formats used by digital cameras. Fortunately, the GD image library in PHP includes some useful functions to simplify this process. In this article, we will discuss some of these, and look at an example that shows how they can be used to convert a true color image into grayscale. We'll then demonstrate how to get a list of the colors that are present in the image, and how to calculate the number of different colors that are present in the image's palette.

imagecolorstotal example

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' ) );
            }
        } elseif ( 'image/webp' == $mime_type ) {
            if ( ! function_exists( 'imagewebp' ) || ! $this->make_image( $filename, 'imagewebp', array( $image, $filename, $this->get_quality() ) ) ) {

  public function getTransparentColor() {
    if (!$this->getResource() || $this->getType() != IMAGETYPE_GIF) {
      return NULL;
    }
    // Find out if a transparent color is set, will return -1 if no     // transparent color has been defined in the image.     $transparent = imagecolortransparent($this->getResource());
    if ($transparent >= 0) {
      // Find out the number of colors in the image palette. It will be 0 for       // truecolor images.       $palette_size = imagecolorstotal($this->getResource());
      if ($palette_size == 0 || $transparent < $palette_size) {
        // Return the transparent color, either if it is a truecolor image         // or if the transparent color is part of the palette.         // Since the index of the transparent color is a property of the         // image rather than of the palette, it is possible that an image         // could be created with this index set outside the palette size.         // (see http://stackoverflow.com/a/3898007).         $rgb = imagecolorsforindex($this->getResource(), $transparent);
        unset($rgb['alpha']);
        return Color::rgbToHex($rgb);
      }
    }