Is there any way to make this code better?

Question

Qingyang 2012-7-17

0
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https://ww2.mathworks.cn/matlabcentral/answers/43883-is-there-any-way-to-make-this-code-better

Hi, I have this code that draws a rectangle onto an image. However, it is very slow for if I wish to draw multiple rectangles. Is there any better way to draw something onto an image?

function imret = image_dsquare( im, r1, c1, r2, c2, val )
    [imr imc] = size(im);
    imret = im;
    for r = r1:r2
        for c = c1:c2
            if r >= 1 && r <= imr && c >= 1 && c <= imc
                imret(r, c) = val;
            end
        end
    end
end

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Answer 1

Sean de Wolski 2012-7-17

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https://ww2.mathworks.cn/matlabcentral/answers/43883-is-there-any-way-to-make-this-code-better#answer_53854

在 MATLAB Online 中打开

imret(max(r1,1):min(r2,imr),max(c1,1):min(c2,imc)) = val;

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Sean de Wolski 2012-7-18

That is probably as fast as it's going to get for the code you have above...

Why is speed so important? How many time are you actually going to call this? Does it matter if one approach takes a few ten thousanths of a second longer?

Qingyang 2012-7-18

Thanks for your help. I was calling this maybe >1000 times for each run. However, I did come up with another way to draw on the image that was much faster.

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