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Why Do I See Vertical Tearing in My Image Display and How Can I Eliminate This?

Primary Software: Driver Software>>Vision Acquisition Software
Primary Software Version: N/A
Primary Software Fixed Version: N/A
Secondary Software: N/A

Problem:
I notice that when I rapidly update an image display, vertical tearing appears. In other words I sometimes see partial frames update instead of the entire frame update at one time.

For example, if I were to update my display with alternating black and white frames I might see something like the below image.




Why is this and what can I do to eliminate vertical tearing?

Solution:
The IMAQ Image Display does not support vertical synching with the refresh rate of a monitor. The difference in update rate of the display and the monitor will often cause two frames to be displayed at the same time, in turn displaying parts of both frames.  

A work-around is to use IMAQ WindDraw instead of an Image Display along with IMAQ WindNonTearing.

                   

IMAQ WindDraw is similar to an Image Display in that it also displays an image. The difference is WindDraw places the image in a separate window and not on the front panel. 

                               

IMAQ WindNonTearing synchronizes the update rate of your monitor and the IMAQ Window display such that only one frame is seen at a time. Be sure to use WindNonTearing before WindDraw so that the NonTearing property is set before the image is displayed.


Related Links:
NI Vision Acquisition Support

Attachments:
Image Display Tear.png
IMAQ WindDraw.png
IMAQ WindNonTearing.png




Report Date: 10/24/2008
Last Updated: 10/31/2008
Document ID: 4QNG6J8Q

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