Plotting pcolor plot on an image at a particular area.

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Hi,
I have done some analysis on a particular region of an image which I now want to plot on the over the image. Following image is an example of what I am trying to get as output ( In my case it is a complete pacman shape but some region would be removed because of NaNs):
Now, I can plot the pcolor of the colored region separatly but am unable to get it with image. Colorbar changes to the gray values. Attached is the relevant binary matrix (region) which shows the region where the profile should be as well as image (img) which is suppose to be in the background and (out) is the values in the disc region.
  2 Comments
waqas
waqas on 4 Oct 2019
Hi Mahesh,
"region" is just a mask of the area in the image "img" over which I am trying to plot pcolor of the third variable. So idea is to plot the gray image in the background and then have pcolor plot over it. I hope this clearifies the statement. End result would be similar to something like the attached image with the question statement.

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Accepted Answer

Walter Roberson
Walter Roberson on 8 Oct 2019
pcolor() accepts x and y arguments as well as the data, so to plot it on top of something else, plot the other things first, "hold on", then pcolor() passing in appropriate coordinates.
pcolor() is, by the way, surf() followed by view(2) internally, except that pcolor() does not accept all of the options that surf() accepts.
  3 Comments
waqas
waqas on 9 Oct 2019
Thank you for the suggestion. It was much simpler approach and did the job perfectly.
Cheers,

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More Answers (1)

darova
darova on 4 Oct 2019
You can just merge images
clc,clear
load matlab.mat
[m,n] = size(img);
[X,Y] = ndgrid(1:m,1:n);
Z = (X.*Y).*region; % try (X+Y)
Z = Z/max(Z(:)); % just scale 0 .. 1
% make RGB image: RED - 1, GREEN - changes, BLUE - 0
% result: red to orange
I1 = cat(3,Z*0+1,Z,Z*0);
mask = repmat(region,[1 1 3]);
I2 = double( repmat(img,[1 1 3]) );
I2 = I2/max(I2(:)); % scale 0 .. 1
I = I1 .* mask + I2 .* ~mask; % merge images
imshow(I);
cm = flipud(autumn);
colormap(cm)
h = colorbar;
  20 Comments
darova
darova on 8 Oct 2019
You can hide ticks
set(ax2,'xtick',[])
set(ax2,'xticklabel',[])

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