Imagick::getImageHistogram

(PECL imagick 2, PECL imagick 3)

Imagick::getImageHistogramGets the image histogram

Description

public Imagick::getImageHistogram(): array

Returns the image histogram as an array of ImagickPixel objects.

Parameters

This function has no parameters.

Return Values

Returns the image histogram as an array of ImagickPixel objects.

Errors/Exceptions

Throws ImagickException on error.

Examples

Example #1 Generates Imagick::getImageHistogram()

<?php
function getColorStatistics($histogramElements$colorChannel) {
    
$colorStatistics = [];

    foreach (
$histogramElements as $histogramElement) {
        
$color $histogramElement->getColorValue($colorChannel);
        
$color intval($color 255);
        
$count $histogramElement->getColorCount();

        if (
array_key_exists($color$colorStatistics)) {
            
$colorStatistics[$color] += $count;
        }
        else {
            
$colorStatistics[$color] = $count;
        }
    }

    
ksort($colorStatistics);
    
    return 
$colorStatistics;
}
    


function 
getImageHistogram($imagePath) {

    
$backgroundColor 'black';

    
$draw = new \ImagickDraw();
    
$draw->setStrokeWidth(0); //make the lines be as thin as possible

    
$imagick = new \Imagick();
    
$imagick->newImage(500500$backgroundColor);
    
$imagick->setImageFormat("png");
    
$imagick->drawImage($draw);

    
$histogramWidth 256;
    
$histogramHeight 100// the height for each RGB segment

    
$imagick = new \Imagick(realpath($imagePath));
    
//Resize the image to be small, otherwise PHP tends to run out of memory
    //This might lead to bad results for images that are pathologically 'pixelly'
    
$imagick->adaptiveResizeImage(200200true);
    
$histogramElements $imagick->getImageHistogram();

    
$histogram = new \Imagick();
    
$histogram->newpseudoimage($histogramWidth$histogramHeight 3'xc:black');
    
$histogram->setImageFormat('png');

    
$getMax = function ($carry$item)  {
        if (
$item $carry) {
            return 
$item;
        }
        return 
$carry;
    };

    
$colorValues = [
        
'red' => getColorStatistics($histogramElements, \Imagick::COLOR_RED),
        
'lime' => getColorStatistics($histogramElements, \Imagick::COLOR_GREEN),
        
'blue' => getColorStatistics($histogramElements, \Imagick::COLOR_BLUE),
    ];

    
$max array_reduce($colorValues['red'] , $getMax0);
    
$max array_reduce($colorValues['lime'] , $getMax$max);
    
$max array_reduce($colorValues['blue'] , $getMax$max);

    
$scale =  $histogramHeight $max;

    
$count 0;
    foreach (
$colorValues as $color => $values) {
        
$draw->setstrokecolor($color);

        
$offset = ($count 1) * $histogramHeight;

        foreach (
$values as $index => $value) {
            
$draw->line($index$offset$index$offset - ($value $scale));
        }
        
$count++;
    }

    
$histogram->drawImage($draw);
    
    
header"Content-Type: image/png" );
    echo 
$histogram;
}

?>

Here you can write a comment


Please enter at least 10 characters.
Loading... Please wait.
* Pflichtangabe
There are no comments available yet.

PHP cURL Tutorial: Using cURL to Make HTTP Requests

cURL is a powerful PHP extension that allows you to communicate with different servers using various protocols, including HTTP, HTTPS, FTP, and more. ...

TheMax

Autor : TheMax
Category: PHP-Tutorials

Midjourney Tutorial - Instructions for beginners

There is an informative video about Midjourney, the tool for creating digital images using artificial intelligence, entitled "Midjourney tutorial in German - instructions for beginners" ...

Mike94

Autor : Mike94
Category: KI Tutorials

Basics of views in MySQL

Views in a MySQL database offer the option of creating a virtual table based on the result of an SQL query. This virtual table can be queried like a normal table without changing the underlying data. ...

admin

Autor : admin
Category: mySQL-Tutorials

Publish a tutorial

Share your knowledge with other developers worldwide

Share your knowledge with other developers worldwide

You are a professional in your field and want to share your knowledge, then sign up now and share it with our PHP community

learn more

Publish a tutorial