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Description	Automatic PDF to image conversion in java.
Jar Path	org.jpedal.examples.images.ExtractPagesAsThumbnails

Click for java source code link

How to run the code

Windows:	java -cp %jpedalDir%/jpedal.jar org/jpedal/examples/images/ExtractPagesAsThumbnails pdffiles png 50
MacOS X Linux:	java -cp $jpedalDir/jpedal.jar org/jpedal/examples/images/ExtractPagesAsThumbnails pdffiles png 50

This example would create thumbnails of PDF pages as png files at 50% .

Click here for help on running Java programs from the command line

 

An explanation of the command line parameters

This program accepts a number of command line parameters which define the output specifications. These are highlighted in red in the example code above. By default all output is placed in a JPedal subdirectory called thumbnails.

First Parameter:	The name of the directory containing the PDF files to be processed.
Second Parameter:	The output image file type. Choices are tif, jpg and png.
Third Parameter:	The percentage scaling to perform. Values accepted are 1 to 100 (For over 100% we recommend using HiResThumbnailExtractor)

 

Other details

This program has the following features:

• Extracts every page in a PDF file as a separate image (image can be in single Tif). The size of the thumbnail is user definable.
• Fully automated.
• Each thumbnail is extracted as a separate file.
• Choice of image output as either png, tif or jpg.
• Bicubic rescaling for the highest possible image quality.
• User selectable output image format.

 

JPEG image quality/compression

The compression quality of the JPEGs produced can be controlled with the JVM flag org.jpedal.compression_jpeg=value where org.jpedal.compression_jpeg=0 produces very poor, small files, org.jpedal.compression_jpeg=1 produces very large, high quality files and values inbetween produces a tradeoff.

 

How to control image color depth

It is possible to control the color depth of the ouput image using the System property

-Dorg.jpedal.imageType

The value of this variable should match the value of one of the awt.image.BufferedImage static TYPE variables. That variable will be used when creating the output image.

 

Producing compressed or Multi-image Tiffs

This simply requires some additional JVM parameters. Here is example code for Windows modified with new values

java.exe -Dorg.jpedal.multipage_tiff=true -Dorg.jpedal.compress_tiff=true -Dorg.jpedal.jai=true -cp C:\jpedal\jpedal.jar; C:\ jpedal\lib\jai_core.jar; C:\jpedal\lib\jai_codec.jar; C:\jpedal\lib\jai_imageio.jar org/jpedal/examples/images/ExtractPagesAsThumbnails C:\jpedal\testPDF.pdf tif

-Dorg.jpedal.jai=true tells JPedal to use JAI (needed for both features). JAI must also be on the classpath.

-Dorg.jpedal.compress_tiff=true Use Tif compression to reduce filesize.

-Dorg.jpedal.multipage_tiff=true Store all images in a single Tif file.

 

Faster PNG generation

There is a JVM flag org.jpedal.fasterPNG to speedup PNG generation.See JVM options for full details.

 

Links to related articles

Getting started tutorial
JVM options for full details of JVM settings which can enable JAI and compress Tiffs
Additional optional libraries lists items which may be needed for some PDF files or functionality.
HiResThumbnailExtractor is slower but will use the raw images (if bigger than the page) and scale the PDF page up rather than scale the images down.
Create separate images for Text, image and Vector graphics layers
PDF to image conversion Java example code provides just the very bare code needed which you can cut and paste directly into your Java code.