How to count the number of voxels of another color

Hi,

I was wondering how to count the number of voxels of one color in a three dimensional space

Thank you!

[Image Analyst]

By "color" do you actually mean gray level? Because a color information in a 3-D space is actually 4-D. What is the source of your image, and what does it represent? Like color movie frames or something? Or a confocal microscope image?

[Matthew Lee]

I was segmenting a section out of a three dimensional shape, but I wanted to find volume of the segmented portion, so I thought that I could approach it by highlighting the segmentation using a different color and counting the number of voxels of that certain color and then arrange a conversion into cm^3 to find a measure of volume. Is there a way to do this, or is there a better way of going about this volume calculation?

[Rik]

You can use my answer to achieve this. When you have a logical array you can use sum to count the number of voxels.

Answer 1

[Rik]

Similar to how you would do that for 2D:

IM=randi(255,[512 512 400]);
count=sum(IM==200,'all');

%if your release doesn't have the 'all' option:
%count=sum(IM(:)==200);