Image calibration

[Veena]

Hi...can anyone tell me how to go about doing the following image calibration steps done?

I have an image that is grabbed using IMAQ PCI 1424 card using dalsa camera. My image consists of a plain black one with white intensity spots placed at equidistant on the image(something like the one u see in the calibration grid except that the spots here are white and the background is dark).I have to specify a uniform grid around each one of the spot so as to make a selection of the spot. Now for each grid I have to find the centroid and my final output should be an 2-d array which is the centroid of each of the grids.
How can I go about getting this done?
I use LabVIEW Ver. 6.0 and IMAQ vision 6.0.

Thanxs
Veena

[BruceAmmons]

I would suggest using the calibration routines. Invert your image and use it as the calibration grid, with grid spacing of 1. I can't remember if one of the outputs of the calibration is the points of the grid. If not, you could just loop through a range of world coordinates that covers all possible situations and look up the corresponding pixel values.

Bruce

[Veena]

hi...
Iam new to LabVIEW and still in the process of learning...I cant clearly understand your suggestion. I am attaching a sample image file on which the above said operation has to be performed.Can u suggest me clearly about it. And am looking at calculating the centroids of the individual grids.How do I do it?
Thanxs... Veena.

[Himanshu]

Dear Ms Veena,
I have seen your post and I would like to know the detials of your current activity.Please mail me at hmishra@iitk.ac.in I am also involved in Vision activity using a webcam.