what does this line means in the following code? I=I(200:400,250:450,:); and when i change the ratio there comes an error of "index exceeds matrix dimensions"

 I=imread('images/Persepolis_Taureaux.jpg');
I=I(200:400,250:450,:);% about M1:60second % M2:70second % M3:60second
tic
S=regcovsmooth(I,10,4,0.2,'M1');
toc

Answer 1

[Andrew Newell]

The function imread retrieves a 3D array consisting of 2D images in various colors or grayscale. The number of these images depends on the size of the third dimension (see Multidimensional arrays). They may, for example, be the red, green and blue components of the total color. The command I=I(200:400,250:450,:) is taking a rectangular sample out of each of these images. As for how regcovsmooth deals with it, this is software from GitHub that I'm not familiar with.

[misbah mateen]

thanks for your response. i couldn't get what u mean by rectangular chance out of each image?

[Andrew Newell]

Sorry, that was a typo. I meant "chunk", but I edited the above statement to read "sample".

[misbah mateen]

if i wanna get full image then what should i change in this statement?

[Walter Roberson]

For the full image, leave out the line

I=I(200:400,250:450,:);% about M1:60second % M2:70second % M3:60second

Or if you want to leave something there as a placeholder to make it easier to change back, then

I = I(:,:,:);

[misbah mateen]

ok. thank you. it works for full image.

Answer 2

[msahar]

I am assuming that you are particularly asking about regcovsmooth function. This function is used for preserving image smoothing via region covariances. The output S is the structure component extracted from input image I.

Please read the research paper at the link given below,

Download Research Paper

[misbah mateen]

thanks for your response. yeah i am doing the project on that research paper. and i am stuck in this line I=I(200:400,250:450,:);.

[msahar]

This line just scale the image (i is used to take out the desired portion of image) so that it take the form of positive definite matrix.

[misbah mateen]

ok. thank you.

Answer 3

[Image Analyst]

regcovsmooth

It probably wants a gray scale image, not a color image. At least that's what I'd try to get rid of the error message.

tic
I = rgb2gray(I);
S = regcovsmooth(I,10,4,0.2,'M1');

By the way, please pick a more descriptive variable name than I. It looks too must like 1 (one) and l (lower case L).

[misbah mateen]

thanks for ur reponse. it still gives the error of Index exceeds matrix dimensions.

[Image Analyst]

Since none of us have the code for regcovsmooth() and only you do, you're on your own, unless you decide to give us all the code we need to run your program.

[Andrew Newell]

Another option would be to contact the creator of that function.

[msahar]

Link to regcovsmooth

Download Regcovsmooth

[Image Analyst]

The code has virtually no comments and that makes it very hard for someone other than the author to support it. Either that was their intent, or they just don't write very good code. I'd have to spend quite a bit of time to understand what that code does, and you can do that just as well as we can. I suggest you contact the author.