PDF to JPG conversion using PHP

Question

I'm trying to convert PDF to IMG (JPG) with help PHP.

I'm using imagick extension.

this is my code

    $fp_pdf = fopen($pdf, 'rb');

    $img = new imagick(); // [0] can be used to set page number
    $img->readImageFile($fp_pdf);
    $img->setImageFormat( "jpg" );
    $img->setImageCompression(imagick::COMPRESSION_JPEG); 
    $img->setImageCompressionQuality(90); 

    $img->setResolution(300,300);

    $img->setImageUnits(imagick::RESOLUTION_PIXELSPERINCH);

    $data = $img->getImageBlob();

my source pdf file has right dimension (210x297 mm, like A4 has). And everything looks good. But my jpg has page dimension as 842x595 px, and DPI is 72.

and img file much more smaller on paper then pdf, when i had print it.

what is a proper way to make image file from pdf and make it so big as pdf (on paper)

Finally i have implemented everything via ghostscript console command (gs), result is excellent! speed is fast! very fast! — user1016265, May 15 '12 at 19:24

score 11 · Answer 1 · answered Jan 21 '12 at 17:08

You could use imagemagick through exec() or similar, the shell arguments are much less verbose than the PHP extension.

$pdf_file = escapeshellarg( "mysafepdf.pdf" );
$jpg_file = escapeshellarg( "output.jpg" );

$result = 0;
exec( "convert -density 300 {$pdf_file} {$jpg_file}", null, $result );

// at this point $result should == 0 if the conversion was successful

It's the "-density" (which sets the DPI to read the source file as) option that specifically fixes your problem.

Also imagemagick by default uses a -quality setting of 92 for JPEG writing in most cases - so you probably don't need to explicitly declare it.

Fatal error: Only variables can be passed by reference in mypath\index.php on line 6 — Fernando Torres, Mar 06 '20 at 19:35

Alfredo Castaneda Garcia · Answer 2 · 2012-01-01T21:37:10.540

It looks like you missed two setters:

Imagick::setImagePage() http://www.php.net/manual/en/function.imagick-setimagepage.php

And:

Imagick::setImageExtent() http://www.php.net/manual/en/function.imagick-setimageextent.php

In order to get the correct parameters for these functions, you may try the following:

$fp_pdf = fopen($pdf, 'rb');
$params=array();

    $img = new imagick(); 
    $img->readImageFile($fp_pdf);
    /*my modification: */$img->setImageUnits(imagick::RESOLUTION_PIXELSPERINCH);
    /*my modification: */$params=$img->identifyImage();
    $img->setImageFormat( "jpg" );
    $img->setImageCompression(imagick::COMPRESSION_JPEG); 
    $img->setImageCompressionQuality(90); 
    /*my modification: */$img->setPage($params['geometry']['width'], $params['geometry']['height'], 0, 0)
    /*my modification: */$img->setResolution($params['resolution']['x'], $params['resolution']['y']);
    $img->setImageUnits(imagick::RESOLUTION_PIXELSPERINCH);
    $data = $img->getImageBlob();

If you find that some others attributes should be set, then let me show you the information that $params is holding. It may proof useful for you:

$params=array(
    [imageName],
    [format], 
    [geometry] => Array
        (
            [width]
            [height] 
        )
    [type], 
    [colorSpace], 
    [resolution],
        (
            [x] 
            [y]
        )

    [units],
    [fileSize],
    [compression],
    [signature],

)

To be honest, I'm not completely sure if this will work. Is just a try in order to help you. I sincerely hope it does.

Thanks for answer, but how i can imagine what is value i should pass in these functions ? PDF has paper A4 size, how do i know how mucn in px it should to make the same dimension on paper ? or for printing purpose only DPI value will be used ? — user1016265, Jan 01 '12 at 20:09
it does not help. This is info about pdf http://o7.no/uAMcLa. The main strange thing is, i made this convertation using shell_exec("convert -density 300 -units pixelsperinch +matte in out"). and result image become in expected dimensions. — user1016265, Jan 02 '12 at 21:49

score 6 · Answer 3 · answered Apr 23 '13 at 14:53

As mentioned before, setting the resolution before reading the file does the trick:

$fp_pdf = fopen($pdf, 'rb');

$img = new imagick(); // [0] can be used to set page number
$img->setResolution(300,300);
$img->readImageFile($fp_pdf);
$img->setImageFormat( "jpg" );
$img->setImageCompression(imagick::COMPRESSION_JPEG); 
$img->setImageCompressionQuality(90); 

$img->setImageUnits(imagick::RESOLUTION_PIXELSPERINCH);

$data = $img->getImageBlob();

score 6 · Accepted Answer · answered Jan 02 '12 at 04:38

6

ImageMagick uses GhostScript to process JPEGs, so you'd do better to exec GhostScript directly, which would be much more efficient and give you more control. It would also be only 1 exec statement, instead of playing around with the IMagick functions.

answered Jan 02 '12 at 04:38

Alasdair

13,348
18
82
138

in real project I did excatly like you suggested. It's working faster, and result is more expected ;) – user1016265 Sep 21 '12 at 08:05

score 1 · Answer 5 · answered Jan 07 '12 at 15:30

1

You have to call setResolution before reading the image. Otherwise imagemagick will use the default system dpi.

answered Jan 07 '12 at 15:30

Pieter

1,764
1
12
16

PDF to JPG conversion using PHP

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