Imagemagick PDF tp JPG bad quality PHP - php

Question

I have a big pdf file that about >100mb.
I want to save that pdf page by page converting to jpg.
My php script works well but image quality sucks even quailty set to 100. Jpg output max width set to 1024.
Each file size about 2.5mb. I have searched for this problem but i get everytime about command line solutions. I must use php.
$file = 'e-magazine/1/ebook.pdf';
if($file === null && !file_exists($file)) {
throw new \Exception('FILE NOT EXISTS');
}
$nop = new \Imagick($file);
for($i = 0; $i <= $nop->getnumberimages(); $i++) {
$image_file = 'e-magazine/1/'.($i+1).'.jpg';
$im = new \Imagick();
$im->readimage($file.'['.$i.']');
$im->setImageCompressionQuality(100);
$im->setimageformat('jpeg');
$im->resizeImage(1024, 0, \Imagick::FILTER_CATROM, 1);
$im->writeimage($image_file);
$tm = new \Imagick();
$tm->readimage($image_file);
$tm->setImageCompressionQuality(60);
$tm->setimageformat('jpeg');
$tm->resizeImage(200, 0, \Imagick::FILTER_CATROM, 1);
$tm->writeimage('e-magazine/1/thumbnails/'.($i+1).'_thumb.jpg');
}
What can i do to correct file quality?

Answer 1

PDFs are vector, rather than bitmap, based so you need to set the density before reading the file in order to tell ImageMagick what sort of size you are going to need then it can rasterize accordingly on input. Try the following PRIOR to reading the image:
$im->setResolution(288,288);
Then try reducing that value, say to 144, and comparing the quality till you have enough quality. It is a tradeoff of quality versus processing time and memory demand. The higher the number the higher the quality but the longer and the more memory.

Answer 2

My full solution to this with compensation for PNG transparency alpha channels
$im = new imagick();
$im->setResolution(300, 300);
$im->readimage($pdf_path.'_0.pdf[0]');
$im->setImageResolution(300, 300);
$im->setImageBackgroundColor('#ffffff');
$im = $im->flattenImages();
$im->setImageFormat('jpeg');
$im->setImageCompression(imagick::COMPRESSION_JPEG);
$im->setImageCompressionQuality(100);
$im->resizeImage(1200, 0, imagick::FILTER_LANCZOS, 1);