Lending you a hand with image processing – basic techniques 2

In my last post I illustrated some simple techniques to enhance and visualize a hand x-ray image. I showed how to use intensity values as if they were elevation to display the hand in pseudo-relief. I did this in 2 ways using the Matlab command surf: once keeping the elevation range of [0-255] obtained from intensity, and a second time creating a different elevation range (through trial and error) to try to further enhance the relief effect. In the case of the hand x-ray the relief was indeed enhanced but with that also unimportant details that are distracting possibly from the task (for the hypothetical specialist commissioning our image enhancement work) of interpreting the x-ray. Today I want to show you a case in which it would be useful to enhance dramatically the smaller details in an image. Below is a beautiful coin of the Roman Emperor Augustus I found here.

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Lending you a hand with image processing – basic techniques 1


This is a PA ulnar deviation x-ray of my left wrist from last month, which gives a good view of the scaphoid bone from above.

The bone is chipped in the area pointed by the arrow, due to a fall that occurred 20 or so years ago. Somewhere in there, there’s also a tiny detached fragment of cartilage that calcified (as seen in a CT scan at the time). I was lucky, because typically the result of a fall with outstretched hand for people aged 17-40 is the scaphoid fracture, which are known to have unpredictable healing. Lately, however, due to a tendonitis, the fragment too is acting out. I’m left handed so this is causing some trouble, and that’s why the recent x-rays.

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