how to concatenate an image with a matrix horizontally in MATLAB

I have 开发者_运维问答an image img. I want to conactenate it with a matrix of zeros, but horizontally i-e image should appear with black color.

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To get you started, this adds a row of zeros to the bottom of a grayscale image:

result = [img; zeros(1,size(img,2))]

and this does the same to an rgb image:

result = [img; zeros(1,size(img,2),3)]

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To add zeros on to the right hand side of an image

newImg=cat(2,img,zeros(size(img,1),numNewColumns,size(img,3)));