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

imagecolorclosest
imagecolorclosesthwb
GD and Image Functions
PHP Manual

# imagecolorclosestalpha

(PHP 4 >= 4.0.6, PHP 5)

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

### Description

int imagecolorclosestalpha ( resource `$image` , int `$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.

### Parameters

`image`

  An image resource, returned by one of the image creation functions, such as imagecreatetruecolor().

`red`

  Value of red component.

`green`

  Value of green component.

`blue`

  Value of blue component.

`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.

### Return Values

Returns the index of the closest color in the palette.

### Examples

Example #1 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);
?>`

The above example will output something similar to:

    #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).

### Notes

> Note: This function requires GD 2.0.1 or later (2.0.28 or later is recommended).

### See Also

- imagecolorexactalpha() - Get the index of the specified color + alpha
- imagecolorclosest() - Get the index of the closest color to the specified color
- imagecolorclosesthwb() - Get the index of the color which has the hue, white and blackness

imagecolorclosest
imagecolorclosesthwb
GD and Image Functions
PHP Manual