Shawn Lankton Online

The GIMP has long been a rival for Photoshop. It’s free, open source, and has nearly the same feature set! However, I being a staunch old Photoshop user never seriously considered GIMP because I was too attached to the location of the buttons, menus, and keyboard shortcuts and didn’t want to learn a new program.

Thanks to GIMPShop, I don’t have to learn anything! These guys took the GIMP and re-tooled it so that it looks and feels a lot like Photoshop. Since the feature set is almost identical I’m switching. (It also runs great on my mac!) Get more info and download it for yourself from here:

• gimpshop.net (with download links)
• Great post about GIMPshop
• Wikipedia article about GIMPShop

Much of the work on image segmentation that I do requires an initial guess of the answer. This initialization gives the algorithm something to improve. Hopefully, it improves all the way to the correct answer. You can use any manner of contour as an initialization. I like to select slightly different contours while I’m testing to make sure I’m not ‘over-tuning’ my system for some specific set of initial conditions.

Sometimes, it is preferable to use a very close initial outline like this:

(by the way, if you are interested in initializations like this see this code)

However, when you are trying to demonstrate the robustness of your technique (and/or you don’t want to waste time drawing a complicated contour) it is nice to use geometric shapes. Squares are popular, and can be captured using this simple Matlab code.

>>[rect] = getrect(1);

Many things in life are shaped more like ellipses, though. For this case, there are no built-in Matlab functions to get this type of initialization. Fear not! I wrote some simple code that allows you to capture graphically (or define in terms of parameters) an ellipse very simply. The params are major and minor radius (a, b), center location (x0, y0) and angle of rotation (rho).

>>[mask, a, b, x0, y0, rho] = get_ellipse(I, a, b, x0, y0, rho);

Here is an example of the type of initialization you can get (shown in white). Also in the image below you can see the final segmentation in green.

Download this .m file and try it out yourself.

For about one year now, I had resigned myself to the fact that the AC in my car was broken. This meant some hot summers in New Jersey and even hotter ones in Atlanta. Well, last weekend my fried (and personal automotive guru) Jon decided that that was the weekend where the AC got fixed.

Now, I drive a 1986 BMW 325 (E30 type). This is such a sweet little car, but it is old. I had assumed that something horrible had gone wrong and the AC was un-fixable. Oh contraire! Upon investigation, the big problem was that the refrigerant was low. This by itself is an easy problem (go the store, buy a bottle of refrigerant, refill the system).

However, the root cause of the low refrigerant was a leaky low-side valve. These old BMWs originally ran on R12 (that’s the awesomely-cold-environment-destroying kind of refrigerant). They sell conversion kits that allow old cars to accept R134-a (which is safe, Mr. Gore). When my car was ‘converted’ by the previous owner, he had done a poor job and wrecked the valve upon installation. After getting a new conversion kit on the car and filling it with refrigerant, my car blows cold again!!

It is soooo nice to arrive places and not be sweaty : )

This Saturday I took my second expidition into the earth. I went with ORGT caving on a trip into Cagel’s Cavern. This cave has an awesome entrance; a 160′ pit that goes straight down. Looking over the edge with nothing but a rope tied to a little tree to keep you from accelerating too quickly towards the bottom can get your heart pumping!However, after a few rappels, you get the trick of it and you are flying down the ropes! What a rush. Inside, its a very nice view to the top. After enjoying that for a few minutes, we went exploring. I like the old quote from inside a hole in the cave somewhere, “Wow, its tight in here… hey… I don’t think there’s a way through… oh wait…. SWEET! Come on!”

We heard that a few times as we were making our way! This is a really cool way to spend a Saturday. Look out for more caving posts as the year goes on. If only there were cool caves that weren’t 200 miles away.