How does IMAQ SetImageSize modify images?

[Max 90]

How does the Vision/Image Management VI "IMAQ SetImageSize" modify images as it reduces image resolution? Does it "bin" and average pixels to come up with corresponding pixels for the reduced resolution image? If not, how is it different from the Image Manupulation VI "IMAQ Extract," supplied with appropriate X and Y step sizes?

Thanks in advance for any responses.
Max

[BruceAmmons]

Max,

SetImageSize does not do any resampling of the image. It simply changes the size of the allocated memory for storing the image. If you just change the Y dimension, you should get back your original image with either a blank space at the bottom, or with the bottom cut off. If you change the X dimension, I think the image becomes scrambled and useless, unless it was changed in a recent version.

I would not use this routine to modify an image. Use either Extract to get a subset of your original image, or use Resample to stretch the image.

Bruce

[Murugan]

Hi

 I have a question regarding the image size.

   I'm using  Sony XC-ES30 which has 768 (H) x 494 (V) pixels. But in the video display I always get 640 X 480. If I change the image size in region of interest to greater than 640 by 480 it doesnt work. It always shows 640X 480 or any size less than it but not greater than 640 x 480 .

 Please let me know what I'm supposed to do to display a live video image of 768 X 494 .

 I would really appreciate a quick reply.

Thank you

Murugan

[T-Route]

Hello Murugan,

I believe what you need to set is the "Acquisition Window" not the "Region of Interest".  A region of interest is a subset of the acquired image.  The "Acquisition Window" is the actual size of the image that is acquired from the camera.  If you need to acquire an image larger then the standard 640 x 480 you will need to change the "Acquisition Window" parameters that can be found in Measurement and Automation Explorer (MAX) under the Acquisition Parameters tab or in LabVIEW by using an IMAQ property node.  If you are only acquiring an image at 640 x 480 then you will not be able to set the region of interest bigger then that because there will be no image data.  If I did not understand your question then please repost.  I hope this helps.  Have a great day.

Regards,
Mark T
Applications Engineer
National Instruments

[Murugan]

Hi

  Even if I set the window size to 768 X 494 (actual image size according to the camera specification)in the Explorer the live video image is displayed for 649X490 pixels . The actual pixels acquired from the camera  is 768x494 .

 I wanted to display the full live video image 768x494 . How can I do it ?

Thank you

Murugan

[T-Route]

Hello Murugan,

Which frame grabber are you using to capture the image (1409 or 1410)?  Are you using the correct camera file posted on our website HERE that corresponds to the correct frame grabber?  Just to clarify you said "the actual pixels acquired from the camera is 768x494" so do you mean you are able to acquire all of the image and you are just having trouble displaying it or do you mean that when you set the acquisition window size in MAX it automatically changes the image size parameters back to 649x490?  If it is possible could you attach a screen shot of Measurement and Automation Explorer when you are acquiring the image and with the "Acquisition Parameters" tab in view?

Regards,
Mark T
Applications Engineer
National Instruments

[Murugan]

Hi

  I consulted a technical support person from NI before buying the board. They suggested to go for 1405 board as 1407 is obselete.

  Yes according to the camera specifications  the pixels acquired is 768X494.

   I mean that when I set the acquisition window size in MAX to 768x494 live video image that is been displayed is only 641x490. But the over all window size is 768x494.

 I have attached a screen shot of the live video image (from MAX) with the cursor pointing to the right bottom corner of the live video image. It shows pixel 645x490 .It means it acquires approximately 645x490 pixels ?

 Can you please let me know what I'm supposed to do to get all the pixels 768x494 from the camera and display it? Or is it possible with the board I have ?

Thank you

Murugan

[Murugan]

Hi

 I have missed the attachment in the previous email. I have attached a creen shot of MAX in this email.

 Waiting for your reply.

Thank you

Murugan

[CMal]

Murugan,

It looks like you are using the RS-170 format in MAX.  Have you tried using one of the other standard formats, such as CCIR?  The image size of the RS-170 standard is 640x480, so this may be the reason for your reduced image size.  You can learn more about the standard image formats here:

http://zone.ni.com/devzone/cda/tut/p/id/3020

You can select other camera files other than RS-170 by right-clicking on the camera under the Categories menu.  Then select Camera >> Standard >> CCIR.  Please let me know if this is helpful.

Chris M.

Applications Engineer

National Instruments

[Murugan]

Hi

  Thanks for the reply. Thanks for the reference article.

    I changed the format in IMAX . But still I dont get the full image 768 x 494 . Am I missing something ?

    I have attached the screen shot.

   Waiting for the reply.

Thank you

Murugan.