core-bundle/src/Resources/contao/library/Contao/GdImage.php
public function countColors($max = null)
	{
		if (!imageistruecolor($this->gdResource))
		{
			return imagecolorstotal($this->gdResource);
		}

		$colors = array();
		$width = imagesx($this->gdResource);
		$height = imagesy($this->gdResource);

		for ($x = 0; $x < $width; $x++)
		{
			for ($y = 0; $y < $height; $y++)
			{
				$colors[imagecolorat($this->gdResource, $x, $y)] = true;

				if ($max !== null && \count($colors) > $max)
				{
					break 2;
				}
			}
		}

		return \count($colors);
	}
public function countColors($max = null)
	{
		if (!imageistruecolor($this->gdResource))
		{
			return imagecolorstotal($this->gdResource);
		}

		$colors = array();
		$width = imagesx($this->gdResource);
		$height = imagesy($this->gdResource);

		for ($x = 0; $x < $width; $x++)
		{
			for ($y = 0; $y < $height; $y++)
			{
				$colors[imagecolorat($this->gdResource, $x, $y)] = true;

				if ($max !== null && \count($colors) > $max)
				{
					break 2;
				}
			}
		}

		return \count($colors);
	}
Count the number of colors in the image

@param integer $max Stop parsing the image if more colors than $max were found

@return integer The number of image colors