问题
I have a working PDF to PNG conversion script using PHP and ImageMagick but I am having a problem with the speed of the conversion.
I know it works because with a very small PDF the time taken to convert is not that great, but with a 250kb file (still not that large really) it takes in excess of 20 minutes to convert.
Here's the PHP:
//***** GET PATH TO IMAGEMAGICK *****
$path_to_imagemagick = trim(`which convert`);
//***** PATH TO PDF TO CONVERT *****
$path_to_pdf = getcwd() . "/pdf/myfile.pdf[0]";
//***** PATH TO OUTPUT TO *****
$output_path = getcwd() . "/pdfimage/test_converted.png";
@exec($path_to_imagemagick . " -density 72 -quality 60 -resize 150x " . $path_to_pdf . " " . $output_path);
Are there any settings I can change to make this quicker?
If it helps, the image does not need to be a PNG. If JPEG is going to be quicker I'm happy to go with that.
回答1:
ImageMagick cannot convert PDF to raster images by itself at all.
ImageMagick uses a delegate for this job: that delegate is Ghostscript. If you hadn't installed Ghostscript on the same system as ImageMagick, the PDF conversion by convert
wouldn't work.
To gain speed, don't use ImageMagick for PDF -> raster image conversion. Instead, rather use Ghostscript directly (also possible via PHP).
Command line for JPEG output:
gs \
-o ./pdfimage/test_converted.jpg \
-sDEVICE=jpeg \
-dJPEGQ=60 \
-r72 \
-dLastPage=1 \
pdf/myfile.pdf
Command line for PNG output:
gs \
-o ./pdfimage/test_converted.png \
-sDEVICE=pngalpha \
-dLastPage=1 \
-r72 \
pdf/myfile.pdf
Both of these commands will give you unscaled output.
To scale the output down, you may use something like
gs \
-o ./pdfimage/test_converted.png \
-sDEVICE=pngalpha \
-dLastPage=1 \
-r72 \
-dDEVICEWIDTHPOINTS=150 \
-dDEVICEHEIGHTPOINTS=150 \
-dPDFFitPage \
pdf/myfile.pdf
Also please note: You used a -quality 60
setting for your PNG outputting command. But -quality
for JPEG and -quality
for PNG output do have a completely different meaning with ImageMagick (and you may not be aware of it). See also this answer for some details about this.
来源:https://stackoverflow.com/questions/12562471/conversion-pdf-to-png-or-jpeg-is-very-very-slow-using-imagemagick