fastest way to convert multi page pdf to jpg images - php

Question

I'm trying to find the fastest way to convert a multiple pdf in to jpeg images without quality loss. I have the following code:
$this->imagick = new \Imagick();
$this->imagick->setresolution(300,300);
$this->imagick->readimage($this->uploadPath . '/original/test.pdf');
$num_pages = $this->imagick->getNumberImages();
for($i = 0;$i < $num_pages; $i++) {
$this->imagick->setIteratorIndex($i);
$this->imagick->setImageFormat('jpeg');
$this->imagick->readimage($asset);
// i need the width, height and filename of each image to add
// to the DB
$origWidth = $this->imagick->getImageWidth();
$origHeight = $this->imagick->getImageHeight();
$filename = $this->imagick->getImageFilename();
$this->imagick->writeImage($this->uploadPath . '/large/preview-' . $this->imagick->getIteratorIndex() . '.jpg');
$this->imagick->scaleImage($origWidth / 2, $origHeight / 2);
$this->imagick->writeImage($this->uploadPath . '/normal/preview-' . $this->imagick->getIteratorIndex() . '.jpg');
//add asset to the DB with the given width, height and filename ...
}
This is very slow thou, partially because the resolution is so big but is i dont add it, the text on the images is of very poor quality. Also, the fact that i'm saving the image first, and then also saving a smaller version of the file is probably not very optimized.
So does anyone have a better method of doing this? Maybe with only ghostscript?
The minimum requirements are that i need 2 versions of the converted image. A real size version and a version at half size. And i need the width and height and filename to add to the database.

Answer 1

You can use Ghostscript, if you set "-sDEVICE=jpeg -sOutputFile=out%d.jpg" then each page will be written to a separate file.
Note that its not really possible to render a PDF to JPEG 'without quality loss' since JPEG is a lossy compression method. Have you considered using a lossless format instead, such as PNG or TIFF ?
To get the same images at different sizes you will need to render the file twice at different resolutions, you set resolution in Ghostscript with '-r'. The width and height can be read easily enough from the image file, or you can use pdf_info.ps to get each page size. Note that a PDF file can contain multiple pages of different sizes, I hope you aren't expecting them all to be the same....