March 24, 2011

Evaluating ratio meat/fat: an image analysis example

We would like to compute how lean is a piece of meat based entirely on the photograph. Practically, this task should be done with a hand-held device. HP Slate was used with Pixcavator installed.

A similar analysis was done before, with images copied from the internet. This time the images are taken by myself with the tablet’s camera. I bought the meat too myself at the local Kroger:

“PVT selection angus choice boneless beef ribeye steak”, 0.56 lb, $5.59.

Finding the right settings took just a few seconds. I only had to move one slider, the contrast.

The amount of meat is captured by the red contours above. The screenshot is below.

As you can see in the right bottom, (the area of) the meat is about 42% of the whole image.

Now we need to capture the fat. It’s tempting to try to do it directly but capturing light area with white background is never a good idea. It’s much easier to get the whole thing and then do some math.

The total of the whole steak (meat and fat) is about 57% of the total image.

Hence, the amount of fat is (57-42)/57, or about 26%. Not lean!

 Other image analysis examples

March 6, 2011

How I use tablets

Filed under: education,image processing/image analysis software,mathematics,site — Peter Saveliev @ 9:36 pm

I use SMART Tablet PC with Windows Journal in class. This means that I write on the screen of the tablet with a digital pen and the writing instantly appears on the screen for the students to see.

lecture with tabletlecture with tablet

The result is

  • handwriting in bright blue, with other colors used for emphasis;
  • formulas broken into parts based on color;
  • colorful illustrations, copied as many times as necessary to show progress.

In any way it’s better than either chalkboard or PowerPoint.

I found SMART Tablet quite reliable.

In the end of the lecture, the file is immediately published in the pdf format to the class web page.

I use HP Slate to edit the lectures afterward.

HP Slate is a Windows computer in the tablet format.

I use it to correct, clean, extend the lectures to make them more readable. Eventually the lectures are transcribed into articles that you see on this site.

I also I use the tablet for mobile image analysis with Pixcavator (more on that in a later post) and for web surfing.


  • Responsiveness is good for web, adequate for writing.
  • The buttons are just a bit too small for my (average sized) fingers.
  • The pen has to be kept close to vertical for writing and drawing.
  • Resting your hand on the screen might produce lines.
  • Smaller, thicker, and heavier than iPad.