Understanding Quantum Range and Depth in PHP with the ImageMagick Package

The getQuantumRange is a useful function, since many of the ImageMagick functions accept parameters from 0 to a maximum of the Quantum Range.  When getting a return value for this, it doesn't return a string.  It actually returns an array, with one type being a String ('quantumRangeLong') and the other type being a Long Int ('quantumRangeString').  The Quantum value (the difference between the high and the low) is the maximum number of color values expressible in a single pixel within an image.  Sometimes, this is called the number of unique colors expressible in a single pixel.  Here's some sample code and the results, given a color, BMP file photograph that is 600x450 pixels...

<?php

            // Author: holdoffhunger@gmail.com
   
        // Imagick Type
        // ---------------------------------------------

    $imagick_type = new Imagick();
   
        // Open File
        // ---------------------------------------------
       
    $file_to_grab = "image_workshop_directory/test.bmp";
   
    $file_handle_for_viewing_image_file = fopen($file_to_grab, 'a+');
   
        // Grab File
        // ---------------------------------------------

    $imagick_type->readImageFile($file_handle_for_viewing_image_file);
   
        // Get Quantum Range
        // ---------------------------------------------
       
    $imagick_type_quantum_range = $imagick_type->getQuantumRange();
   
        // Print Results
        // ---------------------------------------------

    print("<pre>");
    print_r($imagick_type_quantum_range);
    print("</pre>");

?>

Output:

Array
(
    [quantumRangeLong] => 65535
    [quantumRangeString] => 65535
)

The getQuantumDepth works much like the other "Depth" functions and much like the getQuantumRange function.  Like the Depth functions, it returns a value indicating the number of bits to store the unique color values -- 16-bit = 2^16 unique colors, which is 65,535 (counting starts at '0' in binary, as opposed to '1' in decimal).  Like the getQuantumRange function, it returns an array with two values, one being a long integer ('quantumDepthLong') and the other being a string ('quantumDepthLong').  The only difference, besides the variable types, is that the string version has a 'Q' prefixed to it.

Here's some sample code and the results, given a color, BMP file photograph that is 600x450 pixels...

<?php

            // Author: holdoffhunger@gmail.com
   
        // Imagick Type
        // ---------------------------------------------

    $imagick_type = new Imagick();
   
        // Open File
        // ---------------------------------------------
       
    $file_to_grab = "image_workshop_directory/test.bmp";
   
    $file_handle_for_viewing_image_file = fopen($file_to_grab, 'a+');
   
        // Grab File
        // ---------------------------------------------

    $imagick_type->readImageFile($file_handle_for_viewing_image_file);
   
        // Get Quantum Depth
        // ---------------------------------------------
       
    $imagick_type_quantum_depth = $imagick_type->getQuantumDepth();
   
        // Print Results
        // ---------------------------------------------

    print("<pre>");
    print_r($imagick_type_quantum_depth);
    print("</pre>");

?>

Output:

Array
(
    [quantumDepthLong] => 16
    [quantumDepthString] => Q16
)

Official Function Page: http://www.php.net/manual/en/imagick.getquantumrange.php and http://www.php.net/manual/en/imagick.getquantumdepth.php

// Note: All code appearing on the PHP Revolution blog by the blog owner is released under the Hacktivismo Enhanced-Source Software License Agreement (HESSLA), unless otherwise noted.  http://www.hacktivismo.com/about/hessla.php