使用PHP Imagick将PDF转换为JPG时的颜色细微差别问题

Question

I'm experiencing a nuance color change when converting PDF's to JPG's only on certain PDF files. Actually the problematic files are only 2 (out of many), and the nuance change is only on the blue color (from #2a447a to #0630e4, or from #00a4d6 to #00ffff).

The conversion process is pretty much straightforward:

$im = new \Imagick();
$im->setResolution(200, 200);
$im->readImage($path . $this->filename);

$im->trimImage(0);
$im->setImageFormat('jpeg');
$im->setImageCompression(\Imagick::COMPRESSION_JPEG);
$im->setImageCompressionQuality(100);

$im->stripImage();

$tmpFile = sys_get_temp_dir() . '/' . $this->cleanUpImageName($this->label) . '.jpg';
$im->writeImage($tmpFile);

$im->clear();
$im->destroy();

PHP version is 5.4.36, Imagick is 6.6.0-4

Thanks in advance!