Image contrast when using labeloverlay

Question

Matt K. 2022-3-7

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1665904-image-contrast-when-using-labeloverlay

评论： DGM 2022-3-10

Hi,

I have setup an image datastore and a pixel label datastore for some semantic image segmentation I'd like to do and I used some code in an example to show some overlays from some images within my image/pixel lists:

for i=81:85
    im=readimage(imds,i);
    C=readimage(pxds,i);
    B=labeloverlay(im,C,'transparency',0.5);
    figure,imshow(B);
end

However, when I do this, I find that the display range for the image is too wide:

Is there a way to change display range of the background image? It's an int16 image with a [min max] range of [0 4741]

Thanks for your help,

Matt

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Answer 1

DGM 2022-3-7

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1665904-image-contrast-when-using-labeloverlay#answer_912334

编辑：DGM 2022-3-7

在 MATLAB Online 中打开

Try putting your images on a common scale.

im = mat2gray(im);
C = mat2gray(C);

This will put both images in the range [0 1].

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Matt K. 2022-3-10

Thanks! That did the trick.

I see that the image was rescaled to [0,1], but I'm not sure how this worked as C is a categorical matrix (?)

In any case, it now looks the way that it should look:

(a different slice than in the original question)

DGM 2022-3-10

I ... really don't know what to say about the categorical array part. I almost never use categoricals for anything, and I never use datastore stuff so I'm not sure what to expect. At least it seems to be working.

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