image the same and different

Question

lol lolol 2019-9-10

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/479729-image-the-same-and-different

评论： lol lolol 2019-9-10

I have a function:

function [transformed, image] = transformImage(host,transformMatrix)
host=im2double(host);
imageR=transformMatrix * host(:,:,1)*transformMatrix;
imageG=transformMatrix * host(:,:,2)*transformMatrix;
imageB=transformMatrix * host(:,:,3)*transformMatrix;
transformed(:,:,1)=imageR;
transformed(:,:,2)=imageG;
transformed(:,:,3)=imageB;
image = transformed;
transformed = im2uint8(image);
if transformed==im2uint8(image)
    disp("1. true")
else
    disp("1. false")
end
end

and main:

[image, transformedImage] = transformImage(host, transformMatrix);
if transformedImage==im2uint8(image)
    disp("2.true")
else
    disp("2.false")
end

and result is:

1. true
2.false

why inside function is tthe same, and outside is different?

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Answer 1

Stephen23 2019-9-10

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https://ww2.mathworks.cn/matlabcentral/answers/479729-image-the-same-and-different#answer_391249

编辑：Stephen23 2019-9-10

在 MATLAB Online 中打开

You swapped the order of the output arguments when you called the function.

Here is the function definition:

function [transformed, image] = transformImage(...)

But here is how you called the function:

[image, transformedImage] = transformImage(...)

MATLAB has positional input/output arguments. Their names are totally irrelevant.

You swapped the order, so you got the uint8 image in image (the 1st output) and the double image in transformedImage (the 2nd output). Then you converted the uint8 image into a uint8 image (doing nothing whatsoever) and compared that to the double image.