[Insight-users] Mutual Information based Registration on different ROIs for moving and fixed images

[Sharath Venkatesha]

Hi,

I am trying to register 2 images  - the first is a parent image (2000 * 2000 pixels) and the second is a child image ( 640* 480 pixels) which is any sub-part of the parent image.

I am using the following combination:

MutualInformationHistogramImageToImageMetric + MultiResolutionImageRegistrationMethod + AffineTransform + RegularStepGradientDescentOptimizer

**** How can I adapt to take only a specified ROI in the parent image and full child image for Mutual Information calculation?

I tried to use SetFixedImageMask() with a mask image (size of parent image, with only the ROI having non-zero values) and set the metric.  It failed with an exception.

**** I assume this mask applied for both fixed and moving images. How can I apply different masks for fixed and moving images?

Image Details:
Moving Image (child image) : 640*480
Fixed Image(parent image): 2000*2000
Approximate start of corresponding area of moving image in fixed image ( top-left) (x,y) = (600,800) 
Approximate area of mask ROI (area to be considered for MI in the Fixed image) : 1200 * 800


**** What initial translation values and transform center should I use for initializing AffineTransform ?
 
**** How can I determine the approximate start point and region in the parent image for calculation Mutual Information ? ( As of now, I am assuming these values)

Thanks,

Sharath Venkatesha