Imagick::getImageChannelKurtosis()
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The getImageChannelKurtosis purpose
说明
public Imagick::getImageChannelKurtosis([int $channel= Imagick::CHANNEL_DEFAULT]): array
Get the kurtosis and skewness of a specific channel.此方法在Imagick基于ImageMagick 6.4.9以上版本编译时可用。
参数
- $channel
Provide any channel constant that is valid for your channel mode. To apply to more than one channel, combine channel constants using bitwise operators.缺省为
Imagick::CHANNEL_DEFAULT
.参考此通道常数列表
返回值
Returns an array withkurtosisandskewnessmembers.
错误/异常
错误时抛出 ImagickException。
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