converting 2d matrix to 3d matrix

I have a question.

first i read .txt file which have rgb information. 66049 * 3 (r,g,b *66049)

i want read this file and convert to 257*257 image.

how can i do this?

thx

Answer 1

[Stephen23]

Try this:

Y = reshape(X,257,257,3)

For example, a matrix with R, G and B columns, rearranged into a 2*4*3 array:

>> X = [11,12,13;21,22,23;31,32,33;41,42,43;51,52,53;61,62,63;71,72,73;81,82,83]
X =
   11   12   13
   21   22   23
   31   32   33
   41   42   43
   51   52   53
   61   62   63
   71   72   73
   81   82   83
>> reshape(X,2,4,3)
ans(:,:,1) =
   11   31   51   71
   21   41   61   81
ans(:,:,2) =
   12   32   52   72
   22   42   62   82
ans(:,:,3) =
   13   33   53   73
   23   43   63   83

Answer 2

[Star Strider]

If you want to convert your image to a (257x257) grayscale image, use the rgb2gray function. There are also Image Processing Toolbox Image Type Conversion functions if you have access to them.