A couple of IMAQ 16-bit image questions

[Scott_R]

Warren,

I see what you mean. I have tried modifying the code several times and I am repeating the behavior that you described. I am going to investigate this further and I will let you know what I am able to find out.

Regards,
Scott R.
Applications Engineer
National Instruments

[Scott_R]

Warren,

I checked further into the issue that we saw with this system and it appears that the problem is specifically with the display. I tried using the same LUT on an image where I used the IMAQ Cast Image where I cast the 16-bit image to an 8-bit with a shift of 4 bits and the display looked as I expected with 0 displaying blue and 4095 displaying red. So the casting method in general works, but it is specifically the casting method associated with the image display that exhibits this problem.

Try using the IMAQ Cast Image function instead and let me know if the problem persists.

Regards,
Scott R.
Applications Engineer
National Instruments

[WNM]

Hi Scott,

This works for me as well. I've attached a revised copy of the 12-bit test VI that I posted earlier just in case anyone was following this thread besides me and wants to see what you suggest in action.

I'm glad I only have 12-bit images to worry with because I still think that there is something wrong with the "IMAQ ArrayToImage" VI with its "I16" input for more-than-8-bit data. It works well enough for 9-through-15 bits but once you need to use that last bit, which in the case of I16 data is the sign bit, things appear to break down. Try my revised VI to see how 16-bit images do not follow the pattern that all the others exhibit. FWIW, the help file has this to say about that I16 input: "Image Pixels (I16) is a 2D array of 16-bit integers. This input is required if the image connected is a 16-bit image. Use this input only to create a 16-bit signed image."

Who ever heard of a "signed image" (other than Hollywood celebrities and their fans)?

IMHO, this should really be a U16 input.

Anyway, thanks again for the work-around and I trust that you'll let someone on the development end of things know about the problem with the Image Display control/indicator.