noise image frame grabber 1407

[delirious]

I am using IMAQ-1407 to capture images from a infrared vidicon camera. the camera has RS-170 analog output, 525lines vertical resolution and 650 lines horizontal resolution. When I hook the camera to the TV, the images are clear and smooth. however this is not the case when I try to capture images using NI Measurement and  Automation Explorer. The image is like the one as attached. There are vertical lines along the spot which have a certain period.

So I was wondering if I am doing a major mistake along the line because I cant figure out this periodic noise source.

thanks

memet

[AnalogKid2DigitalMan]

I have a hunch it is not noise, but rather a loss of video sync between the camera and the framegrabber. You may want to verify proper camera configuration settings in MAX.

[delirious]

yes, I agree. It must be a syncronization issue. any ideas on how to fix this? the camera has a Genlock In input.

mehmet

[Scott_R]

Hello,

The PCI 1407 expects an image frame that will be 640 pixels wide and 480 pixels tall.  These are the dimensions of a standard RS-170 video signal.  Since you are passing a nonstandard (650x525) video signal into the board, the horizontal and vertical synchronization portions of the video signal are not going to be aligned with what the board is expecting.  This is probably the cause of the distortion that you are seeing.  At what frame rate is your camera generating images?  Standard RS-170 accepts 30fps video signals.

To properly view your video signal in Measurement and Automation Explorer (MAX) or LabVIEW, there are three possible options. 

First, select the Acquisition Parameters tab for your 1407 in MAX and try changing the acquisition window width and height.  You may also need to adjust the top and left offsets.  Try adjusting the width and height first, though.

Second, you could adjust the camera settings (on the camera itself) so that the camera will generate images that are 640x480.  You will need to check the camera documentation to find out if this is possible.

The other option is to use either a PCI 1409 or 1410 to acquire your images.  These boards have the ability to receive images that are of differing dimensions and different frame rates.  For the 1409, you will need to provide a pixel clock for the board.  This can be generated either by the camera or by another device.  The 1410 has additional functionality that allows it to automatically lock onto the video signal and buiilt its own pixel clock. 

Try these solutions and let me know if you have any additional questions.

Regards,
Scott R.
Applications Engineer
National Instruments

[delirious]

Hello Scott,

thank you for your response. it was very enlightining. I dont know if you noticed on the image I sent before, there is something wrong with the horizontal resolution. if it was vertical, that would mean horizontal lines passing along the screen. I doubt that this problem arises from horizontal syncronization.

I've tried the things you told me, I played with the height and width first, and with the left and top boundaries. As I was changing, I observed that the Fps is changing, actually getting smaller, like 15fps. Usually it is 30fps, as it is a standart for RS-170. Unfortunately I could only try the first one since the second one is not possible for this camera. I havent got better results yet, the same problem continues.

I also want to say, I actually bought a cheap TV card and I tried to grab images with 640x480 resolution. The results are pretty good. It is just like when I connected the camera to the TV directly. Even when you change resolution to 320x240, it is still good.

One thing I noticed when the camera is connected to the TV and to the MAX at the same time, when you move the image (a spot on the image, everywhere is dark except the white spot, so I move the camera around)  from left to right and from top to the bottom so that the spot reaches the end of the available screen,  the image on TV is actually smaller than the image on MAX. you can still see something on MAX while you dont see anything on TV when the image is at the edges.

I hope I am more informative of my problem this time.

thank you

Mehmet

[delirious]

I forgot to say, the dimensions of the analog signal is 700x525 not 650x525. sorry for the misinformation. 525 vertical lines and 700 horizontal lines. this is an analog camera but the equivalent pixel size is 18umx18um.

[Scott_R]

Hello,

What model of camera are you using with this?  Could you send a datasheet for that camera?  What type of TV are you using and what type of connection are you making to it? 

What values are you using for the start and stop clamp parameters?  Try varying those values slightly.  Does that help?

Is this pattern constant or do the lines flicker or move?  This could help to narrow down the cause of the issue to either noise or locking.

Regards,
Scott R.
Applications Engineer
National Instruments

[delirious]

Hi,

I am using ElectroPhysics' Micronviewer 7290A. It is an analog Vidicon camera for infrared imaging. I am basically connecting a 75ohm BNC cable to the 1407 frame grabber card. I've tried several other cables and connectors as well.

now there is some flicker. but those vertical lines are not moving or I cant notice the moving. there are small moving horizontal lines but they are hardly noticable.

I am going to go ahead and play with the clamp parameters. I am also sending the datasheet of the camera.

thanks so much

mehmet

[delirious]

Hi,

I've played with several parameters including clamp, nothing seems to work. There is definitely flicker and it makes the image worse. I am sending a screen snapshot which shows the difference between the capture from the 1407 Frame Grabber Card and a TV Card.

[Scott_R]

Hello,

Are you using the same cable to connect to the 1407 that you are using for the TV card?  What type of TV card are you using?

What bitdepth are you using for the acquisition?  If the bitdepth of the camera you are using is greater than eight, try acquiring images into LabVIEW and then try modifying the 16-bit display mapping for the image display.  Try using several different mapping strategies.  LabVIEW and MAX both display images with 8-bit resolution.  If you acquire images with any greater bit-depth than that, the default is that the max and min intensities are found and mapped to 255 and 0 respectively. 

Regards,

Scott R.

Applications Engineer

National Instruments