How to calculate random shift intensity difference (RSID) feature?

12 次查看（过去 30 天）
Sara Salimi
Sara Salimi 2018-12-8
评论： Sara Salimi 2018-12-30
Hi,
I have 3D patients volumes saved in a matlab variable.
I need to extract random shift intensity difference (RSID) feature, this feature compares the intensity of the current voxel x and another
voxel x + u with random offset u, ` f(x, u) = I(x + u) − I(x)`, where u is a random offset vector.
My question is
  1. How many neighbors of a specific voxel needs to be considered to calculate RSID?
  2. How to find them with matlab code?
Your help is appreciated

请先登录，再回答此问题。

回答（1 个）

Image Analyst
Image Analyst 2018-12-9
I think you'd have to scan your 3-D value one voxel at a time.
If you just want the intensity difference over all the neighbors, you can simply use convn with a kernel of all -1 excel the center being 26
kernel = -1 * ones(3,3,3);
kernel(2,2,2) = 26;
kernel = kernel / 26; % So output is in same intensity range as input.
output = convn(inputImage, kernel, 'same');
Why do you want the difference at just one randomly located pixel instead of the average over ALL neighbors?
  6 个评论
显示 4更早的评论
Sara Salimi
Sara Salimi 2018-12-11
编辑：Sara Salimi 2018-12-11
Could I ask is image3d the input 3D array of image, and diffimage is the output? Once I am running the last code, I am getting an error:
Subscript indices must either be real positive integers or logicals.
Error in (line 10)
randomPixel = double(inputDataVol(row+ur, col+uc, slice+us));
The intensity range for the original image has been normalized between [0,1].
Once I am running the first code, After applying the following code,
kernel = -1 * ones(3,3,3);
kernel(2,2,2) = 26;
kernel = kernel / 26; % So output is in same intensity range as input.
output = convn(inputImage, kernel, 'same');
I get an image like for RSID that I have show for a specific slide and the ranges of values is between [-0.3517:0.6728]
and for RSPD I get the following image for a specific probability map of structure, the values ranging [-0.6063: 0.6893]
Sara Salimi
Sara Salimi 2018-12-30
Thanks for your help,
I found an easier way to do this:
shiftRange=[-1,1]; % defining a shift range
u=[randi(shiftRange),randi(shiftRange),randi(shiftRange)];
I2 = imtranslate(I,u);
Id=imabsdiff(I,I2); % the difference between original image and shifted imag
However I a not sure should I shift with a bigger range or not, sth like this:
u=2*[randi(shiftRange),randi(shiftRange),randi(shiftRange)]-1;
makes the shift range changes between [-3,3]

请先登录，再进行评论。

类别

在 Help Center 和 File Exchange 中查找有关 Image Segmentation and Analysis 的更多信息

标签

产品

Community Treasure Hunt

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

Start Hunting!

Translated by