NI-IMAQ Save Function

[J Gudenkauf]

I am developing software in Visual C++ to Grab an image off of the buffer of the IMAQ PCI-1424, and the full size of the image is 1392x1039. Using the imgPlot function is there a way to put the whole image in a window that is 560x370 ?? or is there another way??
Right now I am srinking the Region of Interest(ROI) to fit in this space but when I also want to save the full image into a *.tif file. Therefore, before I call the imgSessionSaveBufferEx function I change the ROI back to the full size, Snap the image, then save it. This ,however, only gives me a piece of the picture but the size of the saved file is correct. 1/3 of the picture is an actual image and the rest is all black. The image height is correct but the width is not. Any help, su
ggestions, on this problem would be wonderful.

[Alan Hagler]

Hello J Gudenkauf,

Here is a little clarification to the problem you are experiencing.

When you reduce the Region of Interest (ROI), you are reducing the amount of the image that is transferred from the framegrabber.
- In your case, the original image is 1392 x 1039, so the entire image is sent from the camera to the framegrabber (1424).
- When you set the ROI, the framegrabber will only transfer the ROI accross the PCI bus to system memory (allowing more PCI bandwidth for other processes).
- The ROI will now fit the space you have, but the entire image is not available to save (so this is the reason for the black pixel border).

Here are couple of suggestions that I have to work around this issue:
- If you have IMAQ Vision, there is a function (IMAQ
Resample) that will resize an image. One application could be to creating thumbnails of an image (same Field of View but lower resolution). A similar function is IMAQ Extract that will crop a subset of the image (smaller Field of View but preserving the image resolution). Both of these functions require IMAQ Vision.
- NI-IMAQ (the driver for the 1424) has the ability to scale an image by capturing every other, 4th or 8th pixel. The Field of View is preserved, but the image resolution is lose. You can access this parameter in MAX by adjusting the Scale parameter (property of the camera).

Here are some insights to your issue, and please let me know if you have any questions,

Alan Hagler