Find the differences - 14x14 Images
<p>I have 23 images, they all are 14 pixels x 14 pixels.</p>

<p>In each one there's a letter on a white background (255 255 255 RGB).</p>

<p>I want to compare them and find unique blank pixels to identify that letter.</p>

<p>For example after that comparing procedure I would like to say that a image 14x14 that has the pixel number (3 width, 2 height) white is an "A" for sure.</p>

<p>Is it possible?</p>

<p>I have the main loop to check every pixel but I'm stuck now:</p>

<pre><code>function getpixelat($img,$x,$y) {
    $rgb = imagecolorat($img,$x,$y);
    $r = ($rgb &gt;&gt; 16) &amp; 0xFF;
    $g = ($rgb &gt;&gt; 8) &amp; 0xFF;
    $b = $rgb &amp; 0xFF;
    return $r.$g.$b;
}

for( $y=$inity; $y&lt;$h; $y++) {
   for( $x=$initx; $x&lt;$w; $x++) {
       $pixel = getpixelat($img,$x,$y);
    }
}
</code></pre>
