How to convert image in form of RGB (2-D matrix)

Question

I have an image of size 128x128. I have applied imread function of matlab on it, A= imread(first.jpg); but this is returning me a 3-D array 128x128x3 , how can I convert it to a 2-D matrix consisting of 3 columns R, G, B (one column for each color)?

Do you want to obtain a matrix thas has 3 columns and 16384 (128^2) rows, that is one rows per pixel? — marcoresk, Nov 14 '16 at 13:35

score 2 · Accepted Answer · answered Nov 14 '16 at 13:42

2

A = imread('first.jpg');
Npixels = size(A,1)*size(A,2);
newA = reshape(A,[Npixels,3]);

answered Nov 14 '16 at 13:42

itzik Ben Shabat

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thanks. it's working absolutely fine, can you also tell me how can I convert this back to jpg image? – jklm Nov 14 '16 at 13:53
@Tehreem Fatima To get back to the original size you will need to save the image size after loading it `Asz = size(A);`. Then perform a reshape operation after processing `origA = reshape(newA, Asz);` – jodag Nov 14 '16 at 16:15
yes, what jodag wrote is correct, if you wish to save it `imwrite(origA,'newImage.jpg','jpg');` @TehreemFatima – itzik Ben Shabat Nov 14 '16 at 18:47

How to convert image in form of RGB (2-D matrix)

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