How to mask the data of no information?

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Amjad Iqbal
Amjad Iqbal 2022-9-21
评论： Amjad Iqbal 2022-9-22
Dear Matlab experts,
I need to mask out data with no information and want to keep data for only targets of interest.
I have attached one image in which data with no information is masked out and retain with target information.
I have attached .mat file, could you please guide on how to mask the information of no use and get only target region?
Thank you!
Best Regards,
Amjad
load('two_targets.mat'); % data
imagesc(intensity,[-45 0]);
I need to keep target area as given in image below and maskout information of no use for spatial mean operation.
I used to cut data or keep points of target but it affects spatial mean operation.
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Walter Roberson
Walter Roberson 2022-9-21
What do you mean by "spatial mean" for this purpose?
What are the boundaries you want to mask with? Your .mat file does not contain anything that looks like a mask. Is the rule that two circles have to be constructed, both with center at half-height, with the two touching at half-width? If so then we would need to know the radius to use.
Amjad Iqbal
Amjad Iqbal 2022-9-21
Dear @Walter Roberson
From .mat file we can have this image named *output* given below.
Now I need to keep information of these two circular targets, according to the colormap its value varies roughlt from -20 to 0
I want to keep this information and mask out rest of the information below -45 to -20 with NaN as given in image above
having white background and two targets.
After that I need to apply sliding window for spatial mean operation.

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采纳的回答

Chunru
Chunru 2022-9-22
Ran in:
websave("two_targets.mat", "https://www.mathworks.com/matlabcentral/answers/uploaded_files/1132000/Two_targets.mat");
load('two_targets.mat'); % data
imagesc(intensity,[-45 0]);
intensity(intensity<-20) = nan;
figure
imagesc(intensity,[-45 0]);
  2 个评论
Walter Roberson
Walter Roberson 2022-9-22
Ran in:
3 x 3 sliding window (sliding one pixel at a time)
websave("two_targets.mat", "https://www.mathworks.com/matlabcentral/answers/uploaded_files/1132000/Two_targets.mat");
load('two_targets.mat'); % data
imagesc(intensity,[-45 0]);
intensity(intensity<-20) = nan;
imagesc(intensity,[-45 0]);
[min(intensity(:)), max(intensity(:))]
ans = 1×2
-19.9535 0
smoothed = blockproc(intensity, [1 1], @(block) mean(block.data(:), 'omitnan'), 'Border', [1 1], 'TrimBorder', false);
imagesc(smoothed);
[min(smoothed(:)), max(smoothed(:))]
ans = 1×2
-19.9535 0
Amjad Iqbal
Amjad Iqbal 2022-9-22
@Chunru and @Walter Roberson Thank you dear both!
It helps me a lot and work perfecly, and I learnt somthing new, I really appriciate your inputs

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