is pixel similar

← getHSL   isPixelSimilarQuantum →
Checks the distance between the color described by this ImagickPixel object and that of the provided object, by plotting their RGB values on the color cube. If the distance between the two points is less than the fuzz value given, the colors are similar. Deprecated in favour of ImagickPixel::isPixelSimilar().

A distance of '1' is the maximum distance in the color space e.g. from 0, 0, 0 to 255, 255, 255 in RGB color space.

The only difference between ImagickPixel::isSimilar and ImagickPixel::isPixelSimilar is that isSimilar needs to be scaled by the quantum value.

// The tests below are written with the maximum distance expressed as 255
// so we need to scale them by the square root of 3 - the diagonal length
// of a unit cube.
$root3 = 1.732050807568877;
$tests = array(
    ['rgb(245, 0, 0)', 'rgb(255, 0, 0)', 9 / $root3, false,],
    ['rgb(245, 0, 0)', 'rgb(255, 0, 0)', 10 / $root3, true,],
    ['rgb(0, 0, 0)', 'rgb(7, 7, 0)', 9 / $root3, false,],
    ['rgb(0, 0, 0)', 'rgb(7, 7, 0)', 10 / $root3, true,],
    ['rgba(0, 0, 0, 1)', 'rgba(7, 7, 0, 1)', 9 / $root3, false,],
    ['rgba(0, 0, 0, 1)', 'rgba(7, 7, 0, 1)', 10 / $root3, true,],
    ['rgb(128, 128, 128)', 'rgb(128, 128, 120)', 7 / $root3, false,],
    ['rgb(128, 128, 128)', 'rgb(128, 128, 120)', 8 / $root3, true,],
    ['rgb(0, 0, 0)', 'rgb(255, 255, 255)', 254.9, false,],
    ['rgb(0, 0, 0)', 'rgb(255, 255, 255)', 255, true,],
    ['rgb(255, 0, 0)', 'rgb(0, 255, 255)', 254.9, false,],
    ['rgb(255, 0, 0)', 'rgb(0, 255, 255)', 255, true,],
    ['black', 'rgba(0, 0, 0)', 0.0, true],
    ['black', 'rgba(10, 0, 0, 1.0)', 10.0 / $root3, true],);
$output = "<table width='100%' class='infoTable'><thead>
        <tr>
        <th>
        Color 1
        </th>
        <th>
        Color 2
        </th>
        <th>
            Test distance * 255
        </th>
        <th>
            Is within distance
        </th>
        </tr>
</thead>";
$output .= "<tbody>";
foreach ($tests as $testInfo) {
    $color1 = $testInfo[0];
    $color2 = $testInfo[1];
    $distance = $testInfo[2];
    $expectation = $testInfo[3];
    $testDistance = ($distance / 255.0);
    $color1Pixel = new \ImagickPixel($color1);
    $color2Pixel = new \ImagickPixel($color2);
    $isSimilar = $color1Pixel->isPixelSimilar($color2Pixel, $testDistance);
    if ($isSimilar !== $expectation) {
        echo "Test distance failed. Color [$color1] compared to color [$color2] is not within distance $testDistance FAILED." . NL;
    }
    $layout = "<tr>
        <td>%s</td>
        <td>%s</td>
        <td>%s</td>
        <td style='text-align: center;'>%s</td>
    </tr>";
    $output .= sprintf(
        $layout,
        $color1,
        $color2,
        $distance,
        $isSimilar ? 'yes' : 'no'
    );
}
$output .= "</tbody></table>";
return $output;

// The tests below are written with the maximum distance expressed as 255
// so we need to scale them by the square root of 3 - the diagonal length
// of a unit cube.
$root3 = 1.732050807568877;
$quantum = \Imagick::getQuantum();
$tests = array(
    ['rgb(245, 0, 0)', 'rgb(255, 0, 0)', 9 / $root3, false,],
    ['rgb(245, 0, 0)', 'rgb(255, 0, 0)', 10 / $root3, true,],
    ['rgb(0, 0, 0)', 'rgb(7, 7, 0)', 9 / $root3, false,],
    ['rgb(0, 0, 0)', 'rgb(7, 7, 0)', 10 / $root3, true,],
    ['rgba(0, 0, 0, 1)', 'rgba(7, 7, 0, 1)', 9 / $root3, false,],
    ['rgba(0, 0, 0, 1)', 'rgba(7, 7, 0, 1)', 10 / $root3, true,],
    ['rgb(128, 128, 128)', 'rgb(128, 128, 120)', 7 / $root3, false,],
    ['rgb(128, 128, 128)', 'rgb(128, 128, 120)', 8 / $root3, true,],
    ['rgb(0, 0, 0)', 'rgb(255, 255, 255)', 254.9, false,],
    ['rgb(0, 0, 0)', 'rgb(255, 255, 255)', 255, true,],
    ['rgb(255, 0, 0)', 'rgb(0, 255, 255)', 254.9, false,],
    ['rgb(255, 0, 0)', 'rgb(0, 255, 255)', 255, true,],
    ['black', 'rgba(0, 0, 0)', 0.0, true],
    ['black', 'rgba(10, 0, 0, 1.0)', 10.0 / $root3, true],);
$output = "<table width='100%' class='infoTable'><thead>
        <tr>
        <th>
        Color 1
        </th>
        <th>
        Color 2
        </th>
        <th>
            Test distance * 255
        </th>
        <th>
            Is within distance
        </th>
        </tr>
</thead>";
$output .= "<tbody>";
foreach ($tests as $testInfo) {
    $color1 = $testInfo[0];
    $color2 = $testInfo[1];
    $distance = $testInfo[2];
    $expectation = $testInfo[3];
    $testDistance = ($distance / 255.0);
    $color1Pixel = new \ImagickPixel($color1);
    $color2Pixel = new \ImagickPixel($color2);
    $isSimilar = $color1Pixel->isPixelSimilarQuantum($color2Pixel, $quantum * $testDistance);
    if ($isSimilar !== $expectation) {
        echo "Test distance failed. Color [$color1] compared to color [$color2] is not within distance $testDistance FAILED." . NL;
    }
    $layout = "<tr>
        <td>%s</td>
        <td>%s</td>
        <td>%s</td>
        <td style='text-align: center;'>%s</td>
    </tr>";
    $output .= sprintf(
        $layout,
        $color1,
        $color2,
        $distance,
        $isSimilar ? 'yes' : 'no'
    );
}
$output .= "</tbody></table>";
return $output;