Image Displayed in a Picture Control Flickers

Solution

Picture controls erase the previous image in the display each time it is updated. The result is a white frame between each image.

Try enabling Smooth Updates and Synchronous Display on the Picture Control you're using to display your images. Synchronous Display ensures that all updates to the picture control you're using are shown, and Smooth Updates reduces the flicker caused when an image is erased and re-drawn upon updating. This should resolve the flickering issue, but can reduce the performance of your acquisition slightly.
If you are using IMAQ Grab to acquire your image, use a property node and set the Erase First property to Do not Erase (a value of 0). This should give a smooth display.
If you have LabVIEW 7.0 or later, then you should be using the native Image Display control, which allows you to efficiently display an acquired image in LabVIEW.
If that does not resolve the flickering, check if the data being collected is uncorrupted by saving the images to disk, either using the functions provided by the IMAQ driver or the Graphics and Sound palette which ships with LabVIEW. If some of the images are black, ensure that your network utilization isn't 100% in Windows Task Manager. If utilization is high, try updating your network driver or reducing your resolution.