## matlab algorithm question

### James (view profile)

on 21 Jul 2011

The below link shows an algorithm I want to try and use and I have a few questions about.

Firstly, I am assuming that when i=0, the first frame of a video is titled caltrain000.

for i = 0:30
imgINumber = i;
imgPNumber = i+2;

I also want to know what the below code does? Because when I try and run the code with my own video frames I get the error - "Index exceeds matrix dimensions".

imgI = imgI(:,1:352);
imgP = imgP(:,1:352);

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### D (view profile)

on 21 Jul 2011

In regard to your second question,

a = a(:,1:3)

redefines a to be all rows of the current matrix, but only columns 1 through 3.

So, say

a = [ 1 2 3 4 5 6; 7 8 9 10 11 12; 13 14 15 16 17 18];

then you get

>> a = a(:,1:3)
a =
1     2     3
7     8     9
13    14    15

### Fangjun Jiang (view profile)

on 21 Jul 2011

When i=0, imgIFile='./caltrain/gray/caltrain000.ras'

The operation is like crop an image. All rows are selected, but only column 1 to 352 (pixel?) are selected.

James

### James (view profile)

on 21 Jul 2011

Do you know why the image need to be cropped like this for motion estimation?

Fangjun Jiang

### Fangjun Jiang (view profile)

on 21 Jul 2011

No idea. I guess it might be related to the size of the image.

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