PHP Unconference Europe 2015

Imagick::paintTransparentImage

(PECL imagick 2.0.0)

Imagick::paintTransparentImageChanges any pixel that matches color with the color defined by fill

Description

bool Imagick::paintTransparentImage ( mixed $target , float $alpha , float $fuzz )

Changes any pixel that matches color with the color defined by fill.

Parameters

target

Change this target color to specified opacity value within the image.

alpha

The level of transparency: 1.0 is fully opaque and 0.0 is fully transparent.

fuzz

The fuzz member of image defines how much tolerance is acceptable to consider two colors as the same.

Return Values

Returns TRUE on success.

Errors/Exceptions

Throws ImagickException on error.

Changelog

Version Description
2.1.0 Now allows a string representing the color as the first parameter. Previous versions allow only an ImagickPixel object.

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User Contributed Notes 3 notes

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quickshiftin at gmail dot com
23 days ago
Have a look at this thread on Stackoverflow for the answer regarding how to determine the max intensity of an image.

http://stackoverflow.com/questions/26239130/determine-max-possible-intensity-of-image/26240656#26240656

In short here is the code to make the $fuzz parameter behave more like you would expect (it now represents a percentage between 0-100). The $fuzz value should now be a float between 0 and 1.

class SaneImagick extends Imagick
{
    public function paintTransparentImage($target, $alpha, $fuzz)
    {
        $iQuantumDepth = pow(2, $this->getQuantumDepth()['quantumDepthLong']);
        return parent::paintTransparentImage($target, $alpha, $fuzz * $iQuantumDepth);
    }
}
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alain at ocarina dot fr
3 years ago
The fuzz is just working well in a range of 0 to 65535.

I suggest you to try to move fuzz on a color spectrum image.

1/ Get a color spectrum ( Google Image has a lot )

2/ Try this code :

<?php

   
function fuzzTest($source, $target, $fuzz) {

       
// Loads image
       
$im = new Imagick($source);

       
// Resizes images to make them easily comparable
       
$im->resizeImage(320, 240, Imagick::FILTER_LANCZOS, 1, true);
       
       
// Apply fuzz
       
$im->paintTransparentImage($im->getImagePixelColor(0, 0), 0, $fuzz);
       
        
// Writes image
       
$im->setImageFormat('png');
       
$im->writeImage($target);
       
$im->destroy();
        
        return
true;
     }

     for (
$i = 0; ($i <= 10); $i++) {
        
fuzzTest('spectrum.png', "test_{$i}.png", (6553.5 * $i));
         echo
'<img src="test_' . $i . '.png" />&nbsp;';
     }

?>
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Anonymous
5 years ago
Actually it does seem to work just not the way expected perhaps.

Looking at the fuzz option on ImageMagick's site (http://www.imagemagick.org/script/command-line-options.php#fuzz), "The distance can be in absolute intensity units or, by appending % as a percentage of the maximum possible intensity (255, 65535, or 4294967295)."

As it requires a float, the percentage value won't work so it actually one of the max intensity values.  In my case, the images I was working with seemed to have max intensity values of 65535.  So a fuzz of 6500, for roughly 10%, seemed to do the trick.

The part that might be problematic though is how do you determine the max intensity of a color/image?  Using a static 6500 would be fine until I would have to convert an image with a max intensity other than 65535.  If it's 255 it would wipe the entire image.  Or fall far short on the fuzz with the larger value.
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