ni 1764 and line scan.

[Juurma]

Dear all,

The NI 1764 smart camera supprots 1/2 and 1/4 scan modes. Is it possible to use the camera in linescan mode - say use only one or few lines of the CCD matrix? 

If yes, what is needed for that? Some special modules?

If no, could this be emulated with software?

Thank you in advance,

Mart

[BruceAmmons · Accepted solution]

I would assume you could just adjust the acquisition window to only include a few lines, perhaps just one.  I don't know if the camera frame rate would increase, though.  You would have to assemble images from the lines yourself, but that is fairly easy.  Create a destination image with the size you want and copy the source image into it one line at a time.

Bruce

[Juurma]

Hi again,

I guess I found the answer already. The IMAQ Configure list.vi has an input named Region of Interest where it is possible to define the portion (ROI) of the image to acquire.

Regards,

Mart

[Michelle_N]

Bruce has a good point. The 1764 is an area scan camera that supports partial frame acquisition - 1/2 and 1/4 frame. Using partial scanning will increase your frame rate as then only part of the sensor is being read. Acquisition window, on the other hand, should not affect your frame rate. This is the same for the ROI input you mentioned. You should not see an increase in frame rate by making your ROI smaller.

Does that answer your question?

[Juurma]

Dear all,

Thank you, I think I understand now. The increase in frame rate is not that important at the moment. We just have to make a proof of concept using available equipment.

I did not expect to have higher frame rate than in the case of 1/4 scan mode at the moment. 

One more thing: Some of the cameras do have the option to adjust the area that it uses to acquire images (similar to NIs 1/2 and 1/4 scan). Are the scan modes bound to hardware with the NI camera so that the user can not define its own scan modes? How is the half and quarter scan realised?

All the best,

Märt

[Michelle_N]

It is hardware bound as far as true acquisition is concerned. The other option is changing your acquisition window - but, as discussed above, the camera still acquires all the pixels from the sensor. A smaller acquisition winodw will cause the unused pixels to be dumped. The key difference is that this method still acquires ALL pixels from the sensor and dumps what pixels are unused while Partial Scan Mode is only taking the pixels that are needed - there is no need for dumping here. This is the reason that the frame rate is sped up.

Here is an excerpt from the 17xx User Manual:

"Partial scan mode is a method of obtaining higher frame rates by reading
out only a portion of the image from the sensor. Partial scan is frequently
used when an application requires higher speed but less resolution than the
sensor offers in full scan mode. The NI Smart Camera supports 1/2 scan
and 1/4 scan. In 1/2 scan, shown in Figure 3-2b, one half of the image is
read out from the center of the sensor and the rest of the image is discarded
to enable a faster start of the next frame. In 1/4 scan, only one quarter of the
image is read out. Figure 3-2 illustrates the portion of the sensor exposed
during partial scanning."

Is this more clear?

[Juurma]

Yes, thank you, it is very clear now.

Case closed 🙂

All the best,

Mart