CCITT encoding in PDF files – Introduction

CCITT is a form of compression used in PDF files to squeeze down black and white data. This makes the PDF smaller (so faster to load and send). When the PDF page is decoded, the data is decompressed and converted back into the black and white image.

We have been doing some work on improving our CCITT decoder, so it seemed like a good item to write a series of articles about. The full list of articles is:-

• CCITT encoding in PDF files – Convert CCITT data into a TIFF image
• CCITT encoding in PDF files – black and white facts
• CCITT encoding in PDF files – rows and height gotcha
• CCITT encoding in PDF files – Decoding CCITT data
• CCITT encoding in PDF files – G31D CCITT data overview
• CCITT encoding in PDF files – Decoding G31D CCITT data

Would you like to know more about PDF files?

This post is part of our “Understanding the PDF File Format” series. In each article, we discuss a PDF feature, bug, gotcha or tip. If you wish to learn more about PDF, we have 20 years worth of PDF knowledge and tips, so click here to visit our series index!

Do you need to read or write Tiff files in Java?

Our JDeli image library offers a range of advantages over ImageIO and alternatives for Tiff files, including:

• prevents heap related JVM crashes
• reads 1-32 bit bilevel, grayscale, rgb, argb, cmyk, acmyk, ycbcr Colorspaces, and converts to sRGB BufferedImage
• implements both Little and Big Endian Byte Ordering
• decompresses uncompressed, CCITT group 3 and 4, Deflate/Adobe Deflate, LZW, Packbits
• support for Single, Multi-file, Tiling, Planar (Chunky, Separated), Predictor, 16,32 bit floating samples
• improve read performance
• supports threading
• superior image scaling algorithms

Learn more about JDeli, or download it to try it yourself.

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