IMAQdx Get Image 2 VI: Buffer Number Mode "Last" And "Last New" Differences

Updated Mar 26, 2023

Reported In

Software

  • LabVIEW

Driver

  • NI-IMAQ
  • NI-IMAQdx
  • NI-IMAQdx 21.0

Issue Details

I am acquiring images in LabVIEW using Vision Acquisition VIs, and I would like to know the difference between buffer number modes of the function IMAQdx Get Image 2.vi, specifically the difference between Last and Last New modes. 

Solution

A basic understanding for the buffer modes can be found by right-clicking the function and choosing the help option.

Below you can see more information on the comparison of two different buffer modes: 

The main difference between Last and Last new is that the Last New will not get any image from the buffer until it is unique. It will not output an error, rather skip the duplicate frame and not acquire it, and do it all over again unless a unique one is appeared in the input. The mode New is going to wait and acquire every new input from the buffer regardless of its uniqueness.
 

Additional Information

The Acquire Most Recent Image.vi example acquires images continuously and displays the images in an image indicator using a grab acquisition. It uses the Last New acquisition mode to get the most recent image to avoid waiting for a new image to be acquired, and return it only if it's a new one never encountered in the circular buffer.

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