Imagick setColor not working with php

Question

I've tried setting all pixels to black. But it isn't working. I am getting the same image as original.

Here is my code:

$image = new Imagick(__DIR__."/image_new.jpg");

$i=0;
$j=0;

while ($i < 100)
{
    $j=0;
    while($j < 100)
    {
         $pixel = $image->getImagePixelColor($i, $j); 
         $pixel->setColor("#000000");
         $j++;
    }

    $i++;
}

header("content-type:image/jpeg");
echo $image;

Image size is 100x100.

Any ideas?

Answer 1

The Imagick::getImagePixelColor will return an ImagickPixel object; which, would have copied data from the originating Imagick object. After altering the pixel's data/state, you would need to "sync" the pixel back to the image. To help with this process, a ImagickPixelIterator object has been provided -- see Imagick::getPixelIterator. Here's a quick example

$image = new Imagick(__DIR__."/image_new.jpg");
$pixel_iterator = $image->getPixelIterator();
foreach($pixel_iterator as $i => $pixels)
{
 if( $i < 100 )
 {
  foreach($pixels as $j => $pixel)
  {
   if( $j < 100 )
   {
    $pixel->setColor("#000000");
   }
  }
 }
 $pixel_iterator->syncIterator();
}

header("content-type:image/jpeg");
echo $image;