How to shear an imagesc image

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Linda Toca
Linda Toca on 21 Oct 2021
Answered: Pranjal Kaura on 26 Oct 2021
I have an image, created using imagesc function from a data matrix, like so:
imagesc (myarray, [-50 0]);
which I am then trying to shear by an angle a using the following code:
a = tand(10);
T = maketform('affine', [1 0 0; a 1 0; 0 0 1] );
B = imtransform(A,T,'cubic','FillValues',orange);
orange = [255 127 0]';
But I keep on failing, as I guess I'm not defining A (my original image created using imagesc) correctly.
Could anyone please explain how to define it correctly so it works as an input for the imtransform function?
Thank you.
Linda Toca
Linda Toca on 21 Oct 2021
Well, if I define A as A= imagesc (myarray, [-50 0]); and the try to to run B, i get:
Error using imtransform>check_A (line 479)
A must be a nonsparse numeric array.
Error in imtransform>parse_inputs (line 373)
args.A = check_A(varargin{1});
Error in imtransform (line 266)
args = parse_inputs(varargin{:});
So I know the problem probably lies in how I define the A

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Answers (1)

Pranjal Kaura
Pranjal Kaura on 26 Oct 2021
Hey Linda,
Using functions 'imtransform' and 'maketform' is not recommended because of compatibilty considerations. You can use 'imwarp' and 'affine2d' instead. Here's a code snippet addressing the changes
a = tand(10);
T = affine2d( [1 0 0; a 1 0; 0 0 1] );
B = imwarp(img,T,'cubic','FillValues',0);
Could you share more information regarding your usecase and why you need 'imagesc' function? Also the complete code, wherein you're defining 'A'.

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