topic configure imaq in Machine Vision

configure imaq

Mic_Scale — Tue, 16 Aug 2005 12:31:55 GMT

Hello !

I've tried to use the Imaq 1410 for non-standard video input. My video is a 0 - 1 Volt analog signal, and I use 2 external syncronization signals (Hsync and Vsync). Hsync and Vsync are both TTL 0 - 5 Volt, 15.62 khz (Hsync) and 50 Hz (Vsync). I tried to configure the Measurement and Automation Explorer with the following options:

Video Lock Mode: External H lock

Channel 0 camera: (All kinds of them which are in the list: VGA, CCIR, NTSC, PAL, RS-170, AREA SCAN, 30/50/60/25 HZ PROGRESSIVE SCAN, LINE SCAN, JAI CV-A1, JAI CV-M1.

When I press on the "Snap" or "Grab" Icon in MAX, I get the "Error 0xBFF6001F - Cannot detect recognizable video source".

When I use the option:

Video Lock Mode : Standard

and connect a standard NTSC camera to the IMAQ 1410, I get a good picture, it works.

Can anyone please tell me how to configure my IMAQ in order to be able to see an image with Video, Hsync and Vsync signals ?

Re: configure imaq

MarcoPolo5 — Wed, 17 Aug 2005 16:41:13 GMT

From the specs you have listed, the 1410 should be able to handle your video signal (however you did not list the image size ie:640x480).

The 1410 uses a PLL (phase lock loop) to generate an internal pixel clock for a video signal that is non-standard (not 640x480). The PLL parameters in the camera file must be set to match the expected video input - these settings are not available through the Measurement and Automation Explorer interface as of now.

A custom camera file can be requesested by using the the link at the bottom of Camera Advisor (www.ni.com/camera). This provides a form to fill out and an email address to send the form to.

Re: configure imaq

Mic_Scale — Thu, 18 Aug 2005 10:51:25 GMT

Thank you for your answer !

My system is composed of LSM (laser scanning microscope) , which generates the video output in correlation with the laser scan position. The LSM controller generates the HSYNC and VSYNC signals according to the laser spot position. The image size is flexible - 256x256 or other square sizes.

How would you recommend to reconfigure the system and the camera setup in order to be able to acquire an image ?

(I have an absolute control over the HSYNC, VSYNC signals. I am also able to generate through the LSM control a pixel clock with various frequencies, however this clock is not synchronized with the HSYNC signal.)

Up until now the only thing that I was able to get was some kind of an image output (just a bunch of dots) (from the Measure and Automation Explorer) by setting HSYNC to 4 KHZ and VSYNC to 200 HZ, I played with the image resolution of various sizes. Even then, the GRABBING function lasted for the most for a few seconds, it always outputs the error "Error 0xBFF6001F - Cannot detect recognizable video source" after a short time. When I used other HSYNC frequencies, it did not work.

Can you please also explain to me what HSYNC, VSYNC, image size values are acceptable to the IMAQ 1410 PLL that I can use ? It seems that there is some kind of a connection between all these values that I can't figure out.

You also mentioned a camera file that I should request. Given the information I wrote, can you please tell me what options should I check when requesting this non-standard camera file ?

Thanks a million times, waiting for your answer or anyone who can help.

Re: configure imaq

MarcoPolo5 — Fri, 19 Aug 2005 19:42:27 GMT

Here is a preliminary document (should be on our website shortly) on how to configure the 1410 for non-standard analog signals.

Re: configure imaq

Mic_Scale — Mon, 29 Aug 2005 17:14:24 GMT

Thank you for your helpful document, Marco !

I can now see an image in MAX (Measurement and Automation Explorer).

As explained in this IMAQ 1410 document, I've made a camera file, using the technique explained there for non-standard cameras. Only, in my case "area scan camera" did not work for me, so I chose "line scan" and it did, but still wrote the error from my previous question:"Error 0xBFF6001F - Cannot detect recognizable video source" after a while, as before. Next, I changed "DetectPCLK (Yes)" to "DetectPCLK (No)", and it now began working smooth.

As I've described before, my system outputs a Video signal, Hsync and Vsync, therefore I work in the "External H Lock Mode". What surprised me was the fact that weather I unplug VSYNC or connect it, it does not affect the image (is this normal ?), as if the IMAQ does not use this.

The questions I wanted to ask are:

When Grabbing or Snapping pictures on MAX, I have horizontal "shifted" lines reappearing on my image. They appear at different locations on it, like "sparks". They seem as if they're a shifted line from another location of the image itself. In addition it happens that I see a "down shifting" of the frames as can be seen on old TV's that are not set correctly to the broadcasted station.

I've tried changing the following parameters (in MAX and in the camera file):

AcquisitionWindow, MaxImageSize, AcqWinHeightRef, AcqWinWidthRef, ClampStart, ClampStop, VCODivider, DPAOffset, LinePixels, LinePixelsRef.

None of this seemed to help. I suspected that there is a connection between HSYNC frequency and the MaxImageSize or maybe other parameters, and that they need to be set in a specific relation to each other. If this is the case can anyone please explain me how to do that ? Or maybe there is a document ? If not, what can cause this "horizontal noise" ?

In the camera file there are additional parameters which I can't find any documentations explaining their functions. This is very crucial for me, since I would not be able to activate my camera had I used only IMAQ 1410 options given by MAX.

Where could I find information about them, their values and form of use ?

I would very appreciate your help on these issues.

Re: configure imaq

MarcoPolo5 — Tue, 30 Aug 2005 22:35:23 GMT

Yes - changing DetectPCLK to No will allow your board to generate the pixel clock rather than searching for one generated from the camera. Since your camera does not output a pixel clock, this setting would have to be set to No.

The 1410 uses PLL (phase lock loop) when acquiring the image and locks onto the embedded Hsync and Vsync signals of the video feed – separate Hsync and Vsync signals are not required. It uses the timing info to generate the pixel clock needed to capture the image data.

A) Changing the parameters you mentioned:

AcquisitionWindow, MaxImageSize, AcqWinHeightRef, AcqWinWidthRef, ClampStart, ClampStop, VCODivider, DPAOffset, LinePixels, LinePixelsRef

should fix the issue you described - steps 12 through 16 of the previously attached document describe what these changes should do.

I would imagine, from what you described, that a "down shifting" would occur from having too small of a acquisition window height or too much of a top offset. Horizontal shifted lines might be occurring because of too small of a window width is specified or too much left offset (or too little).

As the attached document described, it is an iterative process to get the 1410 to generate a matching pixel clock to what your camera is using.

B) Creating custom Camera Files is not fully supported at this time and there is little documentation available that describes the setup and usage of the additional parameters you see in your file. If you are still unable to acquire a good pic, you can request a camera file from our R&D department through ni.com/camera (see option 4).

I wish I could give you a solid answer as to what setting is off, however, It is difficult to see what is going on without seeing how the changes in the cam file are affecting the image.

I hope this helps.

Re: configure imaq

Mic_Scale — Wed, 07 Sep 2005 03:48:22 GMT

Thanx again, I now have more control over my image.

I managed to recieve a picture from my Line Scan camera (MAX 3.1.3), but it's all blurred and unfocused. Is it possible that even though my camera outputs a good and focused picture, my IMAQ 1410 is not configured properly and it is the one who causes this ?

If so, what can I do about this, are there any parameters that by setting them right can help ?

Besides the camera file used by MAX, are there other files that are used by it and can be tweaked to change IMAQ 1410/camera properties ?

Regards,

Re: configure imaq

MarcoPolo5 — Thu, 08 Sep 2005 22:37:17 GMT

I'm glad to hear that you have a better image. It is possible that the 1410 is causing the image to be "blurry" - to quote the previously attached document again:

16. At this point you may need to adjust one additional parameter in the camera file to fine tune the image quality. Open the camera file in a text editor. The DPAOffset parameter controls the phase offset between the pixel clock and the HSync signal. The valid range is 0 to 63, representing 1 pclk cycle. Most video signals give the best image quality with a value close to or equal to 0. Adjust the value of DPAOffset up and down and observe the effect on the image quality. Between each adjustment, save the camera file and reload it in MAX.

a poor image might also be caused if the camera is sending data faster than the 1410 can aquire - the maximum pixel clock speed is 25.8 MHz when the board is generating the pixel clock internally. This would mean that if you have a 1024 pixels in your linescan, you could go ~25,000 lines/sec. (maybe a little bit slower to account for camera delay between lines).

But it could be just as likely that you have a lense or focus issue.

Hopefully these tips will help out.

Re: configure imaq

Mic_Scale — Sun, 11 Sep 2005 16:44:13 GMT

Thanx, Marco.

But, I think maybe my problem is the opposite. Our machine scans at a low rate of 185 Hz each line, or HSYNC, which means that if I have 1000 pixels, I'm scanning at Pixel-clock rate of 0.185 MHZ.

From what I've read in the IMAQ's manual, the IMAQ 1410 is able to produce an inner Pixel Clock in the range of 2MHZ - 25.8 MHZ, which means that we're far behind. Could this be our problem of not being able to get a focused sharp image ?

Moreover, in the document "Configuring a Non Standard Camera for IMAQ 1410" which you've attached, was said that I should also make sure that 100MHz <= PCLK * VCODivider <= 500MHz (STEP 7), which means that the Minimum P-Clock I should reach is 6.25 MHZ (if I set VCODivider to its maximum 16)..... which sets my P-Clock range up to 6.25 MHZ - 25.8 MHZ.

If this is the cause for our struggle for getting a sharp picture, what can we do about it ? Can't the IMAQ 1410 produce a lower P-clock than 2 MGHZ ? And how can I fulfill the second requirement of 100MHz <= PCLK * VCODivider <= 500MHz ? We cannot reach such a high Pixel-Clock.

Thanx again, we really appreciate your help.

Re: configure imaq

MarcoPolo5 — Mon, 12 Sep 2005 22:29:09 GMT

I'm still confused about what is causing your image to be "blurry" - could you attach a "blurred" picture and if possible a good picture (or at least describe what you are expecting)? How was data previously obtained from the microscope? Is it at all possible to output a pixel clock from your system?

Re: configure imaq

Mic_Scale — Tue, 13 Sep 2005 08:54:56 GMT

Yes, of coarse.

I'm attaching a picture we expect from our Laser Scanning Microscope with a lens of (X8). We got this picture when we used this exact system (and exact linses of coarse), only our scanning routine was controlled automatically by a control, and we used another Image Grabbing card.

I'm also attaching an image we're getting now . Third attachment would be our Scope picture of our Video signal Vs H_Sync signal (H_sync is the upper signal, Video is the lower one).

Our system works in the following way: (It does not output a Pixel clock, only H-sync and V-sync (since we've seen that V-sync is not used by the card, we don't use it).

The microscope is controlled by a computer program which sends the following orders periodically.

******************************************************

Repeat

1. Produce a V-Sync.

1.1. produce an H-Sync.

1.2. scan a line (by sampling from x = 0 to x = 10000, when 1 = basic machine step) and send continuously data to analog OUTPUT.

(line scan takes 200 clocks currently. A clock is a basic amount of time).

1.3. go 3 steps up ( y --> y + 3) (it takes 2 clocks currently).

1.4. go back 10000 steps left (x=10000 to x = 0) (it takes 20 clocks currently).

Repeat ( 1.1 - 1.4 ) steps until frame completed, after 480 times (480 lines scanned).

2. Go back to the origin, which is (x = 0, y = 0)

Until Stopped by user

******************************************************

I control machine's speed of line scanning rate manually and produce an H-Sync after each line. Then I connect the H-sync and the Video signals (Which are on separate lines) to an IMAQ 1410 imaging card and work in the "External H Lock Mode" in "Measurement and Automation Explorer" (MAX).

Thank you.

Re: configure imaq

MarcoPolo5 — Tue, 13 Sep 2005 23:04:27 GMT

I was able to find out more details about the lower end specs of the 1410 board - the PLL does have a lower limit for the H-Sync signal it uses to generate the pixel clock off of. It should be able to go as low as 8kHz line clock rate - however, from what you have described, you have ~1kHz H-Sync signal. Such a slow signal is going to cause abnormal opperation from the PLL and is most likely the cause for your unclear images. If you are not able to speed you acquisition to at least an 8kHz H-Sync signal, you will not be able to grab a clean picture with the 1410. Even oversampling, or setting the pixels generated by the 1410 to be within specs will not compensate for too slow of a H-Sync signal.

Digitizing your signal could be done with a Digitizer board like the PCI-5102 or even with a multifunction DAQ baord like our M-Series (PCI-6220). These boards can be setup with variable clock speeds and re-triggerable acquisitions (which would allow multi line acquisitions). Digitized data can be organized into arrays and then changed into a Image format with the Array to Image.vi that comes with our Vision Development Module - once in the image format, you could perform any vision routine needed.

I'm sorry that there does not seem to be a solution for the 1410. This is a very specialized hardware setup you are using with specs that do not fall into the abilities of the 1410.

Let me know if I can clarify anything further for you or if you have any further questions I can help out with.

Re: configure imaq

Mic_Scale — Wed, 14 Sep 2005 12:44:21 GMT

Thank you, I guess we need to use another device then.

With this limitation of H-sync of ours, could you recommend us of products that would support our LSM ?

I would like to attach our Video signal vs. H-Sync scope picture , so that that would be easier. I would like to stress out the fact that our signal does not have a back porch, front porch, blanking are, ext'... that has a standard Video signal. It outputs data continuosly. I've read that I need an area that would be a "Black reference".

Is there a device that could take our continuous Video signal, without the need to have these clamping areas ? In other words, what do we need to do or what devices to purchase, assuming we cannot change our signals, in order to be able to get a good and clean image ?

Re: configure imaq

MarcoPolo5 — Thu, 15 Sep 2005 21:48:52 GMT

Any of NI's M-Series DAQ boards will have a digitizing rate fast enough for your application and more than enough bit depth (16 bits). The PCI-6220 is the lowest end (does not include any analog outputs - but it doesn't sound like you need any for you application). This board can be setup with a analog input clock rate based on it's internal counters which can be set for any speed up to the max analog input rate of 250 samples/s. You could set the board up to capture each line at a specified rate (since you do not have a pixel clock) and trigger the start of the capture based on your H-Sync signal. The acquisition can be retriggerable, meaning it will capture and digitize the data each time a pulse is received on the trigger or H-Sync line.

The 6220 will accept a differential input. Calibration (or clamping) could be done by sampling the voltage from your system when the output is 0 (or a base level) and then subtracting that value from all of the data you digitize.

The data will be received as an array of double precision values from -1 to 1 volts - which you could then convert to integer values in a 16 bit range - or you can extract the 16 bit value from the 6220 to begin with by extracting "raw data".

The arrays of data can be manipulated and organized into a 2D array that represents your image - the IMAQ Array to Image will convert this into a Image Datatype which can be used in any of the vision processing functions or viewed on the Image Display Control.

Hopefully this gives you a better idea of how this setup would work. Let me know if you have any questions about this approach.

Re: configure imaq

Mic_Scale — Fri, 16 Sep 2005 17:11:47 GMT

Yes, I've heard about this approach.

We actually posses a NI PCI-6025e daq board. I want to start working on what you have suggested. I'm already reading the board's user manual.

Will this board do the job ?

Thing is I really don't have much of an idea how to begin building the physical setup and the Labview program, we haven't worked on this board before.

Could you please help me, knowing how our system works, understand more specifically the signal setup with this board ?

Also, I'd be very grateful for the Labview programming side help, maybe an already written vi's, or close to the video acquisition needs of ours ?

Thank you very much

Re: configure imaq

MarcoPolo5 — Mon, 19 Sep 2005 20:42:44 GMT

The PCI-6052 E DAQ Board will work fine to digitize your laser data. It will digitize a single analog input up to 333kHz.

I attached an examples to help you get started - it is a modified version of a Retriggerable Analog Input DAQmx example

I changed the input to acquire 16 bit raw data (you might need to play around with the scaling so that it ranges over 0 to 1 volt rather than -10 to 10v)

I added a small portion at the end to convert the 1D array of acquired data to a 2D array and then to an image.

I have not been able to test this vi - I have no hardware to simulate what you are seeing, however this code should get you started.

(Code created in LabVIEW 7.1)- requires that you have Vision Development Module

Re: configure imaq

AnalogKid2DigitalMan — Mon, 19 Sep 2005 20:47:53 GMT

MarcoPolo:

Isn't the 6025 a 200Ks/sec 12 bit board? I think you transposed the 2 and the 5 and related the 6052's specs

Re: configure imaq

MarcoPolo5 — Mon, 19 Sep 2005 21:37:51 GMT

Thanks for the correction - the 6025 is a 200ks/s 12-bit - this should still work with the application - since the laser scanning microscopes pixel clock is at ~185kHz. Just remember to change the acquired data conversion to 12 bit rather than the 16 bit setup I set it for.

Re: configure imaq

Mic_Scale — Tue, 20 Sep 2005 17:57:46 GMT

Thank you very much for the vi.

I still do not posses the visual model for Labview, but I have looked at your work. I have a few question about the vi and another about the DAQ 6025e board of ours.

a. How does the retriggering work ? Does it function like a loop which jumps again and again to start the clock frequency ?

b. You have defined 1000 clocks for the counter, so does that mean that after each H-Sync, exactly 1000 pixels are digitized, and then the program waits idle for the next H-Sync ?

c. You have defined [Height * Width] samples to the analog channel, does that mean that the retriggering will continue until all these much samples are taken ? In other words, is this is how you control the end of the acquisition (or the program) ?

d. I think that you have created a snap acquisition. What do I need to change/add if I want a continuous frame grabbing ? (If we suppose that besides H-Sync, I could use V-Sync too as an additional external trigger).

e. Currently we are working on isolating the digital and the analog Input/Output signals on the board in order to protect it from damage. Hence, from technical and financial reasons, we will not be able to use all of our 10 PFI's and not all of our other digital and analog connections, that are on the board. We now need to decide which PFI's and which other digital and analog connections we need for sure for our system to use. Can you please tell me which PFI's and which other digital/analog connection we need for our application ? I really want to get right with it.

Thanks a million times.

Re: configure imaq

MarcoPolo5 — Wed, 21 Sep 2005 20:06:18 GMT

a) retriggering does "function like a loop" - so in the example it will output a finite pulse train (which acts as the sample clock) and then waits till another trigger occurs to repeat.

b) I wired "Image Width" into the number of pulses the counter outputs to digitize the analog signal. You will have to match the "Rate" to allow the number of pulses output to match up to the time your laser scans one line - if the rate is too slow, it will miss the H-sync pulse starting the next line.

c) yes

d) This is a snap acquisition - you would have to add a start trigger (that is retriggerable) that would trigger off of the V-Sync signal - you could setup the current analog acquisition to be triggered this way

e) Here is a link to the E-Series users manual - this has the pinout for your device as well as descriptions of the PFI lines:

http://digital.ni.com/manuals.nsf/websearch/05A25C65C755D8DB86256FD30081687D

If you need consulting help with your project look at the list of alliance members we have in your area:

http://digital.ni.com/productpages/nialliance.nsf/main?readform

If you hook up your analog input in differential mode, there will be a significant ammount of common mode voltage rejection.

From the above maual:

Max working voltage (signal + common mode)

Each input should remain within ±11 V of ground

Overvoltage protection

Signal	Powered On	Powered Off
AI <0..15>	±42	±35
AI SENSE	±40	±25

Common-mode rejection ratio (CMRR), DC to 60 Hz
	Range 10 to 20 mV	85 dB
	Range 100 mV to 1 V	90 dB