The getImageChannelKurtosis function accepts as a parameter any of the ImageMagick channel constants and returns an array containing elements with the two element values of 'kurtosis' and 'skewness.'
For the inputted color values, you have the ImageMagick channel constant values that look like imagick::CHANNEL_UNDEFINED, with "_VALUE" values of: undefined, red, gray, cyan, green, magenta, blue, yellow, alpha, opacity, matte, black, index, all, and default. This is for measuring the particular channel for these colors of their own associated colorspaces.
According to Wikipedia, the Kurtosis is "any measure of the 'peakedness' of the probability distribution of a real-valued random variable" and Skewness (its opposite) is "a measure of the asymmetry of the probability distribution of a real-valued random variable." The more colors vary from the inputted channel constant, you'll be more likely to get a skewness close to zero, and you'll get the opposite behavior from checking the kurtosis value, which makes sense, since skewness and kurtosis are considered mathematical antonyms.
Some sample code :
<?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_channel_kurtosis_red = $imagick_type->getImageChannelKurtosis(imagick::CHANNEL_RED);
// Print Results
// ---------------------------------------------
print("<pre>");
print_r($imagick_type_channel_kurtosis_red);
print("</pre>");
?>
The results for performing this function upon a photo of the ocean...
ImageMagick - Channel Kurtosis
Channel - Undefined :
Kurtosis : 0
Skewness : 0
Channel - Red :
Kurtosis : 0.920611158888
Skewness : 1.52701528976
Channel - Gray :
Kurtosis : 0.920611158888
Skewness : 1.52701528976
Channel - Cyan :
Kurtosis : 0.920611158888
Skewness : 1.52701528976
Channel - Green :
Kurtosis : -0.286520845928
Skewness : 1.05203603783
Channel - Magenta :
Kurtosis : -0.286520845928
Skewness : 1.05203603783
Channel - Blue :
Kurtosis : -0.849997917796
Skewness : 0.807852655795
Channel - Yellow :
Kurtosis : -0.849997917796
Skewness : 0.807852655795
Channel - Alpha :
Kurtosis : 0
Skewness : 0
Channel - Opacity :
Kurtosis : 0
Skewness : 0
Channel - Matte :
Kurtosis : 0
Skewness : 0
Channel - Black :
Kurtosis : 0
Skewness : 0
Channel - Index :
Kurtosis : 0
Skewness : 0
Channel - All :
Kurtosis : 0.509521246195
Skewness : 1.33491479552
Channel - Default :
Kurtosis : -0.349955122843
Skewness : 1.00561407035
Imagick::getImageChannelKurtosis
(No version information available, might only be in Git)
Imagick::getImageChannelKurtosis — The getImageChannelKurtosis purpose
설명
public array Imagick::getImageChannelKurtosis
([ int
$channel = Imagick::CHANNEL_DEFAULT
] )Get the kurtosis and skewness of a specific channel. 이 메쏘드는 Imagick을 ImageMagick 6.4.9 이상으로 컴파일 했을 때만 사용할 수 있습니다.
인수
반환값
Returns an array with kurtosis and skewness members.
오류/예외
오류시에 ImagickException이 발생합니다.
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User Contributed Notes 1 note
holdoffhunger at gmail dot com ¶
12 years ago
