Description:
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After several color allocations, imagecolorallocate seems to no work anymore. See code sample (illogical but point at the problem).

Reproduce code:
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function letter($l, $x, $y, $img)	{
	$color1 = imagecolorallocate($img, 190, 190, 190);
	imagestring ($img, 1, $x+1, $y+1, $l, $color1);
	
	$color2 = imagecolorallocate($img, 190, 190, 190);
	imagestring ($img, 1, $x-1, $y-1, $l, $color2);
	
	$color3 =  in a picture.($img, 255, 0, 0);
	imagestring ($img, 1, $x, $y, $l, $color3);
}
$image = @imagecreate (1200, 500);
$background_color = imagecolorallocate ($image, 255, 255, 255);
for ($i = 0; $i < 100; $i++)	{
	letter($i, $i*12, 50, $image);
} 
header ("Content-type: image/png");	
imagepng ($image);
imagedestroy($image);

Expected result:
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expected : display 1 to 100 red digits with gray shadow in a picture.

Actual result:
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result : displays 1 to 84 red digits with gray shadow in a picture. After 84, digits and shadows are all red. imagecolorallocate seems to not work anymore.