Why is IMAQ USB Snap.vi constantly giving out a 32-bit image?

[mirola]

Hi.

I'm using some USB cameras (uEye) with Direct Show. I use the IMAQ USB camera tools (with Labview 7.1, Vision 7.1.1) as in the examples. In particular I'm working in the snap mode.

I create an U8 image (IMAQ Create) which I use as input to IMAQ USB Snap.vi and I set the camera's video mode to grayscale (Y8) using IMAQ USB PropertyPage.vi

But, I don't get an 8-bit image out of IMAQ USB Snap.vi. The image is always converted to 32-bit RGB. In principal It works like this, but it costs me valuable time to convert the image to 8-bit at some points of the program where I need the image grayscale array.

Cheers,

mirola 

[Elmar_NI]

Hello Mirola,

first of all the usb hardware is only for the education stuff and its not official supported.

http://sine.ni.com/devzone/cda/epd/p/id/5030

But if you read in a color image you will get a 32 bit image.

(Red = 8Bit , Green = 8Bit,  Blue = 8 Bit)= 24bit and the other 8 Bit are reserved.

Please look at the manual of the cam maybe the cam dosent support the grayscale mode.

If you need a higher performance please use a grayscale 1394 cam with the DCAM standard.

Kind regards,

Elmar

[mirola]

Hi Elmar,

Thanks for answering.

Of course, the "not officially supported" thing is a killer argument. But the device shall work with a laptop and, as I know, the firewire cameras need an additional power supply when connected to a laptop 1394.

The camera I use is grayscale and only works properly when I write 8-bit grayscale in its settings (e.g. using IMAQ USB PropertyPage.vi).

As I said, everything I can set is set to 8-bit. The Snap.vi converts the input IMAQ image to 32-bit.

But maybe you are right and it's just that NI's USB Direct Show dll is not treated with high priority (note: I use the most recent one, although I combine it with older LV and Vision versions.) Otherwise I guess I would get more answers here.

On the other hand, if I ask the manufacturer he will probably say I should use his SDK which I don't want at this point.

Best regards,

mirola 

[Elmar_NI]

Hello mirola,

did you try it with the new usb driver version 1.3.0 in the lv 8.6 version.

Did you see the same behavior?

Did you see this behavior  in the normal priority mode?

Or is it possible that you send us the cam for test?

Kind regards,

Elmar

PS: The big problem is that behind the snap function is only a dll call.

PS: We use also 1394 cams in combination with the laptop.

You only need a Y cable because the 4 wire laptop interface dosent support the power supply.

(price about 30 euro)