Cris’s Image Analysis Blog

First of all: Happy New Year!

Over the holidays I’ve been learning about dithering, the process of creating the illusion of many grey levels using only black and white dots. This is used when displaying an image on a device with fewer than the 64 or so grey levels that we can distinguish, such as an ink-jet printer (which prints small, solid dots), and also when quantizing an image to use a color map (remember the EGA and VGA computer displays?). It turns out that this is still an active research field. I ran into the paper Structure-aware error diffusion, ACM Transactions on Graphics 28(5), 2009, which improves upon a method presented a year earlier, which in turn improved on the state of the art by placing dots to optimize the appearance of thin lines. This got me interested in the basic algorithms, which I had never studied before. Hopefully this post will give an understanding of dithering and its history.

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I’m pleased to announce we’ve released a new version of DIPimage and DIPlib, with several relevant changes. For a full list of changes, please see the DIPlib website, here I’ll review the most salient changes.

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Noise in images perturbs measurements and makes the lives of image analysis people interesting. There are many sources of noise, depending on the imaging modality: photon noise, thermal noise, electronic noise, quantization noise, etc. I have just found out about another source of noise: etheric entities. Apparently these etheric entities appear especially in “certain photos of human/reptilian hybrids such as Bush or Obama,” and are completely indistinguishable from other types of noise. I’m not looking forward to test my algorithms against this form of noise.

RSA and DES keys keep growing in length, to keep up with increasing computational power. Keys we were using 15 years ago are laughable now. And according to a nice graph in April’s IEEE Spectrum, ridiculous amounts of computing power are cheaper than ever. I wonder how long before people give up on encryption altogether.

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