VeryDOC Knowledge Base

   VeryDOC PDF Compressor can help you compress color scanned PDF down to the same size as black and white TIFF Group 4 images by JPEG2000 technology. JPEG2000 is an image compression standard and coding system, which was created with the intention of superseding their original discrete cosine transform-based JPEG standard with a newly designed, wavelet-based method. By this method, we can reduce 100 times of their original size while maintaining better image quality and text legibility. Now let us check the JPEG2000  compression effect from the following snapshot. Even if you compress image by 1:100 times, the quality is still good.

     Compress image by JPE2000

In the following part, let us check how to use this software and this technology to compress PDF.

Step 1. Download PDF Compressor

• This software is Windows command line application, when downloading finishes, there will be an zip file. Please unzip it and then check elements in it and find the executable file.
• Before run the conversion, you’d better read the website and help document then you can know more about this software. 

Step 2. Compress PDF by JPEG2000 through command line

• When run the conversion, please refer to the usage and examples.
• Usage:       pdfcompressor [options] <pdf-file> [<out-pdf>]
• When you need to compress PDF by method JPEG2000, please refer to the following command line template. pdfcompressor.exe -jbig2 C:\in.pdf C:\out.pdf
  By this command line, you can compress PDF by JBIG2 arithmetic.
  pdfcompressor.exe -jbig2 -jpx C:\in.pdf C:\out.pdf
  By this command line, you can compress color and grayscale image streams with JPEG2000 arithmetic.
  Now let us check the related parameters:

-jbig2    :by this parameter, you can compress monochrome image streams with JBIG2 arithmetic
-jpx       : by this parameter, you can compress color and grayscale image streams with JPEG2000 arithmetic
-jpxquality <string>: when you need to set Quality for JPX Compression, from 0.0 to 100.0, default is 0.5

• When you need to do batch compression, please refer to the following command line templates. You can either use wild character or use for mode.
   pdfcompressor.exe C:\in\*.pdf C:\out\*.pdf
  for %F in (D:\test\*.pdf) do "pdfcompressor.exe" "%F" "%~dpnF-out.pdf"
  for /r D:\test %F in (*.pdf) do "pdfcompressor.exe" "%F" "%~dpnF-out.pdf"
• This software provides three strategies to compress PDF file.
  1. Subset fonts in PDF files. This method is good when you need to process text based PDF file.
  2. Compress image streams with JBIG2 and JPEG2000 technologies.
  3. Remove unused objects (a garbage collector for PDF files). This method is good when you need to create Web-friendly PDF files

If you need to know more about this software, please visit its homepage and website. During the using, if you have any question, please contact us as soon as possible.

   There are many kinds of PDF files you may meet when you need to compress PDF files. If you compress PDF by the same method, the compression effect will not be good. Take compressing PDF with colorful image for example, VeryDOC PDF Compressor will give you professional method to process them. In the following part, I will show you how to compress PDF by command line.

Step 1. Download PDF Compressor Command Line

• If you need to use this software on the single computer or laptop, please download the server version which either can be used on server or single computer.
• When downloading finishes, there will be an zip file. Please extract it to some folder then call the executable file in MS Dos Windows.

Step 2. Compress PDF with colorful image by command line

• When you use this software, please refer to the usage and example. And this software is Windows application, now it can not work under Mac and Linux version.
• Usage:        pdfcompressor [options] <pdf-file> [<out-pdf>]
• When you need to compress PDF with colorful image, there are some options available for you.

-ci <string>  : when you need to set Color Image Compression, there are three values: jpx, jpg, zip for you to choose.
-cidown         : you can try to downsample color images.
-cidownres <int>       : Set Color Image Resolution. By this parameter, you can try to compress colorful image by adjusting image resolution.
-jpxquality <string>   : Set Quality for JPX Compression, from 0.0 to 100.0, default is 0.5
-cidowntype <int>      :When you need to  downsample type for color images, there are four values for you to choose.

      -cidowntype 0: default
      -cidowntype 1: Subsample
      -cidowntype 2: Average
      -cidowntype 3: Bicubic
Here are some examples:
pdfcompressor.exe -jpx -jpxquality 1 C:\in.pdf C:\out.pdf
By above command line, you can compress PDF by jpx method and specify Quality for JPX Compression as 1. The range of compression quality is from  0.0 to 100.0, default is 0.5. Please check the following two command line templates as examples.
pdfcompressor.exe -jpx -jpxquality 0.5 C:\in.pdf C:\out.pdf
pdfcompressor.exe -jpx -jpxquality 10 C:\in.pdf C:\out.pdf
pdfcompressor.exe -ci jpx -mi jbig2 C:\in.pdf C:\out.pdf
By the above command line, you can compress image by jpx and set Monochrome Image Compression values as jbig2l. Please check more examples in the following part.
pdfcompressor.exe -ci jpx -gi jpx -mi jbig2 C:\in.pdf C:\out.pdf
pdfcompressor.exe -ci jpg -cidown -cidownres 50 -cidowntype 1 C:\in.pdf C:\out.pdf
pdfcompressor.exe -gi jpg -gidown -gidownres 50 -gidowntype 1 C:\in.pdf C:\out.pdf
pdfcompressor.exe -mi fax -midown -midownres 50 -midowntype 1 C:\in.pdf C:\out.pdf

If you need to know more examples and usage, please check them in the readme.txt or on our website. And this software also provides many other methods of compress grey image PDF, or text based PDF file. During the using, if you have any question, please contact us as soon as possible.