Posts Tagged 'Image Processing'

Netpbm and the PGM Format – Part 2

This is the second part of a series on processing PGM format image files in Python. For an overview of what PGM is refer to Part 1. In this part we’ll look at how a PGM file is generated and create a few small images to look at. In part 3 of this series we’ll examine some utility functions to write, read and display PGM image data. Lastly, in part 4, we’ll take a look at a case study of how the PGM format was used for scientific CCD camera testing, and offer some suggestions for how you might be able to use it.

Continue reading ‘Netpbm and the PGM Format – Part 2’

Netpbm and the PGM Format – Part 1

In this series of articles I’ll introduce the Netpbm suite of tools and its simple and versatile PGM image file format, and demonstrate how PGM can be used for image processing and arbitrary data storage in Python.

In this part we meet Netpbm and its PGM file format. In the next installment I’ll present some Python code to read and write a PGM file. Later on I’ll present a simple image viewer to display the data, and lastly, I’ll present some unconventional techniques for storing things other than actual images in the PGM format, along with some reasons for why one might want to do that.

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Free PNG Book Available On-Line

I recently stumbled across this whilst sifting through the Weird Wild Web:

PNG
The Definitive Guide
Greg Roelofs
O’Reilly 1999

pngbook-cover-1.jpg

Released under the GNU Free Documentation License, V1.1.
http://www.libpng.org/pub/png/book/

If you deal with image processing software then you really need to know about PNG. Superior to JPEG for images containing sharp edges and step gradients (i.e. line art and such), PNG uses a non-patented lossless data compression method. While it won’t compress down as much as JEPG, it also doesn’t suffer from high-frequency signal loss, generation loss and compression artifacts (checkerboarding and such). Also see the Wikipedia article on PNG:
http://en.wikipedia.org/wiki/Portable_Network_Graphics