i've an image of size 204x204. after dividing the the image into overlapping blocks,then m using mat2cell i got the following error

I=imread('lina.jpg');

whos I;

fun=@(block_struct) mean2(block_struct.data(:));

B=blockproc(I,[6 6],fun,'bordersize',[3 3]);

C=mat2cell(B,[6 6],[6 6]);

error: =>

Input arguments, D1 through D2, must sum to each dimension of the input matrix size, [0 0].'

error in mat2cell

can u tell what is my mistake n plz rectify it...as soon as

[pammy]

plz tell me whats wrong with the above code...

Answer 1

[Walter Roberson]

In your call

C=mat2cell(B,[6 6],[6 6]);

the second argument must add up to size(B,1), and the third argument must add up to size(B,2).

Also, somehow, your B has come out empty, size 0 x 0, perhaps because you did not use the blockproc options 'TrimBorder', false

[pammy]

sir u mean C=mat2cell(B,size(B,1),size(B,2));

is it correct or not?

if not plz rectify it

[Walter Roberson]

No it is not correct.

C = mat2cell(B, [6 6 6 6 6 6 ... 6], [6 6 6 6 .... 6], size(B,3));

where the first group of 6's has enough 6's to add up to size(B,1) and the second group of 6's has enough 6's to add up to size(B,2)

Answer 2

[Jan]

The dimensions in your MAT2CELL call do not match the size of the input B, which seems to be empty.

[pammy]

actually i want to divide the above

blockproc(I,[6 6],fun,'bordersize',[3 3],'TrimBorder',false);

into B1 B2 B3 B4,....... blocks.. how can i do it...

because i have to deal individually with the blocks...

plz help me in making blocks from blockproc or

is there any other way to deal with this?

regards pammy :)

[Walter Roberson]

What would you do with the over 4500 individual B variables if you had them? Are you planning to code all 4500+ different variable names into your code? And it's going to be obvious to the reader of the code what variable B138 means, and it is going to be obvious that B129 is not in the same row as B128 ?? Please reconsider using individual variable names.

http://matlab.wikia.com/wiki/FAQ#How_can_I_create_variables_A1.2C_A2.2C....2CA10_in_a_loop.3F

[Image Analyst]

mat2cell does not do overlapping blocks/tiles. They are adjacent (touching) but NOT overlapping. You have to decide what you want: tiling with overlapping or tiling without overlapping.

[Walter Roberson]

When blockproc() is called with Bordersize, and with TrimBorder set to false, and if the fun returns something the same size as the data structure member passed into the fun, then the returned array will consist of adjacent tiles expanded out of the overlapping data.

1 2 3 | 4 5 6 7 8 9 | 10 11 12 || 7 8 9 | 10 11 12 13 14 15 | 16 17 18 || 13 14 15 | 16 17 18 19 20 21 | 22 23 24 ||

In the above, the single-| mark the logical edges of the core of the tiles, with the overlap region to the left and right of there; the double-|| mark the logical edges of what was returned by fun and thus the places at which mat2cell should be used to break up the array. The bars have just been added for education purposes here and do not exist in the array; the array itself would look like

   1 2 3 4 5 6 7 8 9 10 11 12 7 8 9 10 11 12 13 14 15 16 17 18 13 14 15 16 17 18 19 20 21 22 23 24