Thread Subject: how to randomly select pixels from an image

 Subject: how to randomly select pixels from an image Date: 5 Apr, 2010 14:28:07 Message: 1 of 6 Hello all, i want to randomly select 1000 pairs of two adjacent pixels from an image to calculate their correlation coefficicent after that. Can any one help me please cause i'm stuck here for along !! and thanks in advance
 Subject: how to randomly select pixels from an image From: us Date: 5 Apr, 2010 15:00:21 Message: 2 of 6 "Jennifer Faggi Renault" wrote in message ... > Hello all, > i want to randomly select 1000 pairs of two adjacent pixels from an image to calculate their correlation coefficicent after that. > Can any one help me please cause i'm stuck here for along !! > and thanks in advance one of the solutions      img=magic(4);      np=4; % <- #pairs to select...      nr=size(img,1);      rp=randperm(numel(img)-nr);      rp=rp(1:np);      plst=[img(rp).',img(rp+nr).'] %{ % plst = % <- based on current RAND state...      10 8       4 14       2 3       5 11 %} us
 Subject: how to randomly select pixels from an image Date: 5 Apr, 2010 15:30:26 Message: 3 of 6 i'm really thankfull for your answer. i think that selection is for horizontally adjacent pixels. Sorry if i bother you but, how can i change that if i want to select pairs of diagonally adjacent pixels ???
 Subject: how to randomly select pixels from an image From: us Date: 5 Apr, 2010 15:39:04 Message: 4 of 6 "Jennifer Faggi Renault" wrote in message ... > i'm really thankfull for your answer. > i think that selection is for horizontally adjacent pixels. > Sorry if i bother you but, how can i change that if i want to select pairs of diagonally adjacent pixels ??? well... - just ad a one (1) to NR in the last step... - and - make sure you check for and remove possible row-overflows... us
 Subject: how to randomly select pixels from an image From: ImageAnalyst Date: 5 Apr, 2010 15:45:19 Message: 5 of 6 Jennifer: I think you may also be interested in the gray level co-occurrence matrix, performed in MATLAB by the function graycomatrix() in the Image Processing Toolbox. It basically gives the likelihood that a gray level is next to the other 256 gray levels. You can specify the 'offset' parameter which is basically what you were asking about.
 Subject: how to randomly select pixels from an image Date: 5 Apr, 2010 15:49:04 Message: 6 of 6 thanks again :)

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