MATLAB Answers

assigning color to binary image

86 views (last 30 days)
Hassan
Hassan on 27 Dec 2011
I have an image consisting of values 1 to 7. I want to show each value with specific color (green,blue,yellow,cyan,magenta,maroon, and sea green). I think I need to use colormap function but dont know how. Any suggestion please?
imshow(BW)
colormap(?)

Accepted Answer

Image Analyst
Image Analyst on 27 Dec 2011
Hassan: Then, try this:
% Create sample data
m=7*rand(150);
imshow(m, []);
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]); % Maximize figure.
% Construct new colormap with 8 rows and 3 columns
% Each row applies to one gray level.
% Create the 8x3 array any way you want.
% Here I'm using the built-in "jet" array
% set up to go over only 8 gray levels.
cmap = jet(8);
% Apply the colormap
colormap(cmap);
colorbar;
  4 Comments

Sign in to comment.

More Answers (2)

Image Analyst
Image Analyst on 27 Dec 2011
That's not a binary image. It's probably a labeled image, which is a double. Look at this snippet of code that assigns a multitude of different colors to the regions:
% Label each blob with 8-connectivity, so we can make measurements of it
[labeledImage numberOfBlobs] = bwlabel(binaryImage, 8);
% Apply a variety of pseudo-colors to the regions.
coloredLabelsImage = label2rgb (labeledImage, 'hsv', 'k', 'shuffle');
% Display the pseudo-colored image.
imshow(coloredLabelsImage);
  2 Comments
Hassan
Hassan on 27 Dec 2011
Actually Walter's code was the one I needed. the image consists of many regions (connected cells). some regions have value 1, some regions have value 2, ...and some have value 7. Sorry if I didn't describe it clearly.

Sign in to comment.


Sukuchha
Sukuchha on 27 Dec 2011
first of all if your image is binary, you cant have values from 1 to 7.
if you have image with values 1 to 7, first you have label the connected components.
CC = bwconncomp(BW);
L = labelmatrix(CC);
RGB = label2rgb(L);
figure, imshow(RGB)taken from help file of label2rgb
see doc label2rgb
  4 Comments
Image Analyst
Image Analyst on 27 Dec 2011
Funny, same function as I used, label2rgb. But you're saying now that you don't have a labeled image and that you don't care about labels or connected regions. So that if you had 15 blobs with gray level 4, then all 15 of those should be the same color. And if you had 42 blobs with gray level 5, then all 42 of those should be the same color (but different than the color used for gray level 4). You can do that with just the regular colormap, like my answer below, without having to use label2rgb at all.

Sign in to comment.

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!