imagecolorclosestalpha

Get the index of the closest color to the specified color + alpha

&reftitle.description; `int` `imagecolorclosestalpha` `GdImage` `image` `int` `red` `int` `green` `int` `blue` `int` `alpha`

Returns the index of the color in the palette of the image which is "closest" to the specified RGB value and `alpha` level.

&reftitle.parameters;

&gd.image.description;

`red`

- &gd.value.red;

`green`

- &gd.value.green;

`blue`

- &gd.value.blue;

`alpha`

- A value between `0` and `127`. `0` indicates completely opaque while `127` indicates completely transparent.

The colors parameters are integers between 0 and 255 or hexadecimals between 0x00 and 0xFF.
&reftitle.returnvalues;

Returns the index of the closest color in the palette.

&reftitle.examples;

### Search for a set of colors in an image

    <?php
    // Start with an image and convert it to a palette-based image
    $im = imagecreatefrompng('figures/imagecolorclosest.png');
    imagetruecolortopalette($im, false, 255);

    // Search colors (RGB)
    $colors = array(
        array(254, 145, 154, 50),
        array(153, 145, 188, 127),
        array(153, 90, 145, 0),
        array(255, 137, 92, 84)
    );

    // Loop through each search and find the closest color in the palette.
    // Return the search number, the search RGB and the converted RGB match
    foreach($colors as $id => $rgb)
    {
        $result = imagecolorclosestalpha($im, $rgb[0], $rgb[1], $rgb[2], $rgb[3]);
        $result = imagecolorsforindex($im, $result);
        $result = "({$result['red']}, {$result['green']}, {$result['blue']}, {$result['alpha']})";

        echo "#$id: Search ($rgb[0], $rgb[1], $rgb[2], $rgb[3]); Closest match: $result.\n";
    }

    imagedestroy($im);
    ?>

&example.outputs.similar;

    #0: Search (254, 145, 154, 50); Closest match: (252, 150, 148, 0).
    #1: Search (153, 145, 188, 127); Closest match: (148, 150, 196, 0).
    #2: Search (153, 90, 145, 0); Closest match: (148, 90, 156, 0).
    #3: Search (255, 137, 92, 84); Closest match: (252, 150, 92, 0).

&reftitle.seealso;

- `imagecolorexactalpha`
- `imagecolorclosest`
- `imagecolorclosesthwb`