Imagick::getImageColors

    (PECL imagick 2, PECL imagick 3)

    Imagick::getImageColors — Gets the number of unique colors in the image

    Description

    public Imagick::getImageColors(): int

    Gets the number of unique colors in the image.

    Parameters

    This function has no parameters.

    Return Values

    Returns an int, the number of unique colors in the image.

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    User Contributed Notes 2 notes

    up
    2
    holdoffhunger at gmail dot com
    12 years ago
    I've had difficulty getting this function to return the number of unique colors. Also, I wanted to be able to have an array with each $key value being the RGB of the pixel, and each $value value being the number of times that pixel occurs. Basically, a frequency list. For example, you would have "1 / 0 / 0" for red as a $key value, and "25" for the number of times that pixel color was in the image. So, I wrote some code to do that, using a combination of readImageFile, getImageWidth, getImageHeight, getImagePixelColor, and a simple x/y parser, like so :

    <?php

    // Test File
    // ---------------------------------------------

    // Note: This file was just a picture of a 5x5 red square
    // inside of a gigantic 521x512 black square, and
    // then I did a bunch of random, yellow zigzags.

    $file_to_grab_with_location = "test.bmp";

    $imagick_type = new Imagick();

    // Open File
    // ---------------------------------------------

    $file_handle_for_viewing_image_file = fopen($file_to_grab_with_location, 'a+');
    $imagick_type->readImageFile($file_handle_for_viewing_image_file);

    // Preset Information
    // ---------------------------------------------

    $frequency_list_of_values = array();

    // Parse Pixels
    // ---------------------------------------------

    $image_resolution_width = $imagick_type->getImageWidth();
    $image_resolution_height = $imagick_type->getImageHeight();

    print(    "Image Resolution: Width - $image_resolution_width / Height - $image_resolution_height<br><br>");

    // Parse Image Top-to-Bottom (Y-Variable)
    // ---------------------------------------------

    for($y = 0; $y < $image_resolution_height; $y++)
    {
    // Parse Image Left-to-Right (X-Variable)
    // ---------------------------------------------

    for($x = 0; $x < $image_resolution_width; $x++)
    {

    // Image Pixel Color
    // ---------------------------------------------

    $pixel_to_examine = $imagick_type->getImagePixelColor($x,$y);

    $pixel_to_examine_color_value_red = $pixel_to_examine->getColorValue(imagick::COLOR_RED);
    $pixel_to_examine_color_value_green = $pixel_to_examine->getColorValue(imagick::COLOR_GREEN);
    $pixel_to_examine_color_value_blue = $pixel_to_examine->getColorValue(imagick::COLOR_BLUE);

    // Set Key Value
    // ---------------------------------------------

    $key_value = $pixel_to_examine_color_value_red . " / " .
    $pixel_to_examine_color_value_green . " / " .
    $pixel_to_examine_color_value_blue ;

    // Increment Array Entry for Color
    // ---------------------------------------------

    if(isset($frequency_list_of_values[$key_value]) == TRUE)
    {
    $temp = $frequency_list_of_values[$key_value];
    $temp++;
    $frequency_list_of_values[$key_value] = $temp;
    }
    else
    {
    $frequency_list_of_values[$key_value] = 1;
    }
    }
    }

    // Print Out Array of Values
    // ---------------------------------------------

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

    /*

    Results:
    ------------------

    Image Resolution: Width - 521 / Height - 512

    Array
    (
    [1 / 0 / 0] => 25
    [0 / 0 / 1] => 264107
    [1 / 1 / 0] => 2620
    )

    */

    ?>
    up
    -1
    amaral dot regis at hotmail dot com
    6 years ago
    O exemplo anterior apresentou números fracionados nas chaves da variável $frequency_list_of_values:

    Array
    (
    [1 / 0 / 1] => 157295
    [0.83529411764706 / 0.87843137254902 / 0.82352941176471] => 1
    [0.80392156862745 / 0.84705882352941 / 0.7843137254902] => 2
    [0.8156862745098 / 0.84705882352941 / 0.78823529411765] => 1
    ...

    Então eu fiz uma alteração que melhora o resultado para quem esta buscando saber quais as cores dominantes na imagem, mostrando a chave com o valor rgb exato:
    <?php

    $file_to_grab_with_location     = $imagepath; //caminho relativo ao arquivo de imagem

    $imagick_type = new \Imagick();

    $file_handle_for_viewing_image_file = fopen($file_to_grab_with_location, 'a+');
    $imagick_type->readImageFile($file_handle_for_viewing_image_file);

    $frequency_list_of_values = array();

    $image_resolution_width = $imagick_type->getImageWidth();
    $image_resolution_height = $imagick_type->getImageHeight();

    print(    "Image Resolution: Width - $image_resolution_width / Height - $image_resolution_height<br><br>");

    for(    $y = 0; $y < $image_resolution_height; $y++)
    {

    for(    $x = 0; $x < $image_resolution_width; $x++)
    {

    $pixel_to_examine = $imagick_type->getImagePixelColor($x,$y);

    if(isset(    $frequency_list_of_values[$pixel_to_examine->getColorAsString()]) == TRUE)
    {
    $temp = $frequency_list_of_values[$pixel_to_examine->getColorAsString()];
    $temp++;
    $frequency_list_of_values[$pixel_to_examine->getColorAsString()] = $temp;
    }
    else
    {
    $frequency_list_of_values[$pixel_to_examine->getColorAsString()] = 1;
    }
    }

    arsort($frequency_list_of_values);
    }

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

    ?>

    Resultado:
    Image Resolution: Width - 1965 / Height - 998

    Array
    (
    [srgba(255,0,255,0)] => 451654
    [srgb(54,52,53)] => 281069
    [srgb(177,51,54)] => 130449
    [srgb(236,50,55)] => 64001
    ...

    O método é demorado para imagens muito grandes, pois ele analisa pixel a pixel.
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