Grid pattern in live image

[viswa]

Hello all,

                      I am using AVT GUPPY F-036B CMOS camera with LabVIEW 8.2. When i try to capture live image from a rough surface after illuminating with a laser beam, i can see a fine grid pattern overlaying on the speckle pattern (Take a closure look at the image). This effect is pronounced when i try to capture subtracted images. I need to obtain data from subtracted images, but because of the grid pattern, can not extract any useful data.

I have never seen this before with other cameras which we have used before.

I beleive that this is caused only due to camera. I tried to change camera setting like shutter speed, brightness, gain etc... but no use still i can see the same grid pattern.Any help would be greatly appreciated.

regards

Viswanath

[muks]

Can you tell the camera setting that you are using?

[viswa]

Hi Muks,

                  Here are the images attached explain all the settings. I know that in external triggering mode i need to set shutter register value at 2000 instead of 1094 to acquire at 25fps. But somehow i could not get 25fps at 2000.

I set the brightness and autoexposure to maximum values just to see effect on the grid pattern otherwise i set these values aroung 120.

Camera can acquire images now at 25fps with external trigger with out any problem, but i can see very fine grid pattern on images.

Any way thanks for the quick reply.

[BruceAmmons]

I don't see any grid pattern at all.  I looked at both images and zoomed in a bit but never saw anything other than JPEG compression artifacts.

It might help to save the images using a non-lossy format such as PNG so all the details are preserved.

Bruce

[AnalogKid2DigitalMan]

I can vouch for Bruce's eyesight- I saw no pattern either in the images.

-AK2DM

[viswa]

Hi Bruce,

                 If you download the image and may be zoom it the central part, i guess you can see some regular pattern seems like a grid.

I was unable to extract information from wrapped phase map. I could see some kind of pattern on wrapped phase.

I trust you because you are an experienced person in image processing.

[muks]

Can you also explain what exactly you want to detect?

[viswa]

I want to detect motion of an object using speckle interferometry. In the process i have noticed some odd results, and noticed some regular pattern which i can see only when the camera captures speckled images. I have checked my sert up, if something is wrong with it but could not find anything.

Then concluded that somekind regular pattern was amsking my results.

I felt if somebody had comeacross like me before.

Regards

viswanath