Are 16-bit greyscale images in IMAQ Vision True 16-bit

Does 16-bit image in Vision control display true 16-bit grayscale (or is it really mapped to 8-bit)?
thanks,
Don

Most displays only provide 8 bits of each color (RGB). These can be combined to create millions of colors, but can still only display 8 bits of grayscale. Very few display are capable of 16 bit display, so the 16 bit images must be converted to 8 bit. It is useful that LV provides several options for the conversion.
Bruce
Bruce Ammons
Ammons Engineering

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Why do 16 bit greyscale images look significantly worse than 32 bit?

Howdy,
I am trying to display a greyscale image from a camera. Parts of the program are written by someone else, and the image comes in as a U16 array. I am using IMAQ create and IMAQ arraytoimage. The image displays perfectly if I use the 'float' inputs on the above to sub vi's, but if I use 16 bit or 8 bit, the image quality is terrible. I would like to be able to display the image as 16bit.
If I save the 16 bit image, and reopen it with another program, it's still just as bad. I have also tried converting the array to I16, and U8, but it makes no difference to the image quality.
From what I understand, there should be very little visible difference between 8, 16 and 32 bit greyscale images. Does anyone have any ideas where the problem might be? my next guess is the camera settings, but I'd love it to be something in my code..
Cheers,
Andy

Andy,
Thank you for contacting National Instruments. The key thing to note is that the image data type that LabVIEW uses is a signed interpretation so you need to do some more conversion to get an Unsigned 16-bit array to display properly as an NI-IMAQ image. Refer to the Knowledge Base: 16-bit Images in NI-Vision for more information on how to do this. Thanks and have a great day.
Regards,
Mark T
Applications Engineering | National Instruments

Why I can't subtract two images in imaq vision builder?

Hi,
I have many times tried but failed to get the objects in a image by subtraction with another image which is background, in imaq vision builder(ver. 6.0). I totally can't use the "operators" command under "greyscale" to subtract the two images becauee all commands under the "greyscale" are always unactivated after two images have been stored in 2 idfferent buffers. I really don't know why and this vision builder is so difficult to use, unbelievable! I followed the instructions in its Help and it's quite simple but I totally failed to make this operation!
Two samples of images have been attached and maybe it's very ease for you to filter out objects(fibers) by subtraction each other. Show me your scrip
t if you can. It's urgent to me.
Or the idea of the way I thought for filtering the objects is wrong? Point out please if you know.
Thanks and Merry Christmas and Happy New year!!
Swedlin
Attachments:
10Img0.jpg ‏27 KB
123Img0.jpg ‏25 KB

Okay, this is not quite as straightforward as it could be, but you can do image subtraction in Vision Builder. The basic idea is as follows:
- select first object image and copy it to buffer 1
- select "image >> get new image" and load your background image from a file.
- put this in buffer 2
- retrieve object image from buffer 1
- perform subtraction. Even though these images appear to be greyscale, they are actually saved as 24-bit RGB images, so you need to use the color operators instead. Vision Builder will only allow you to select steps that are valid for the image you have loaded. You could extract the luminance plane from all of your images to work with 8-bit images if you like.
I have attached below a background image, several object i
mages, my script, and the results of batch processing. You will need to edit the "get new image" step with the correct path to the background image on your machine.
Bruce is right though. This is a bit easier in LabVIEW.
Regards,
Brent R.
Applications Engineer
National Instruments

Reading TIFF images without IMAQ vision

Hi,
Is there anyway to read TIFF images with LV 7.1 but without IMAQ vision? I know it's possible for PNG, BMP and JPEGs, but seems impossible to read TIFFs without IMAQ Vision.
Thanks.
Kian

LabVIEW doesn't do this automatically, but maybe someone has a VI they're willing to share.
Another possibility would be to use an external program to convert the TIFF to another format (BMP for example) and then to read in the BMP picture.
If you're looking to write something yourself, then this might help.
Hope this helps
Shane.
Using LV 6.1 and 8.2.1 on W2k (SP4) and WXP (SP2)

Is there an example somewhere that shows how to acquire StillColor images using IMAQ Vision calls?

I need to be able to acquire images from both composite and RGB channels. I am also confused of how to display them and modify display settings as go from color to grayscale to binary.Thanks.

Jerry,
I have attached a CVI example for doing stillcolor acquisition. If you are using LabVIEW, there should also be shipping examples for stillcolor acquisition under labview\examples\imaq\imaq color.llb
To configure your imaq board for stillcolor acquisition, please refer to the following KB
http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/cc743c416e390c008625683f007562c7?OpenDocument
Hope this helps.
Ken Sun
Applications Engineer
National Instruments
Attachments:
advanced_stillcolor.c ‏8 KB
advanced_stillcolor.h ‏3 KB
advanced_stillcolor.uir ‏19 KB

Curves adjustment layer for greyscale images

If you are editing a greyscale image, the curves adjustment layer is shown in "reverse" style (as you would expect to work with a CMYK image) that that is awkward to work with. If you use Image->Adjustment->Curves, you have the option to invoke the curve display in Light (0-255) or Pigment/Ink % in which the LIGHT does what is appropriate.. It would be nice to have the ability to toggle the Light/Pigment in the Curves Adjustment layer.
I think I remember that, in the good old days of CS/CS2, you could alt-click on the gradient to alter the tonal direction of the curve.

Woops... I just found that the Curves Adjustment layer flyout has a Curves Display Options that allows the setting - and it is sticky. Sorry for the waste bandwidth.

What happens to a 12-bit image in LabVIEW/IMAQ Vision?

I'm using the DALSA DALSTAR 1M30 camera, and we are building a cable for it, and have not yet got it up and running, but I am already programming our application for it. I was wondering, since the IMAQ Vision VI's seem to pertain to 8-bit, 16-bit, and floating point images, I was wondering if they will work fine with a 12-bit image like the one from the 1M30 camera. I was also wondering, if they do work fine, what format the output of a VI like IMAQ ImageToArray will be. Will the 12-bit pixel values be converted into 16-bit?
Thanks for the help.

A 12 bit image is stored within IMAQ as a 16 bit image. Only routines that accept 16 bit images can be used for manipulating the image.
The IMAQ WindDraw converts 16 bit images to 8 bit images for display, using the selected method. You can also manually convert to an 8 bit image for automatic thresholding and other routines that don't accept 16 bit images. For most applications, you will want to shift it 4 bits during conversion so the most significant bits are preserved.
Bruce
Bruce Ammons
Ammons Engineering

Is possible to Convert a 1 bit B&W Tiff image to a 16 Bit Greyscale Tiff image?

Hi there,
I am trying to convert a 1 bit Black & White Tiff image to a 16 Bit Greyscale Tiff image, Anyone out there know if it is possible and how it may be done? We are using Adobe Acrobat 9 Pro Extended.
Any help would be appreciated.
Cheers, Chris

Almost any graphic editor can do it, but it doesn't make a sense. The picture information remain the same - 1 bit. It has nothing to do with Acrobat.

Do IMAQ Cast Image or IMAQ Linear averages give different results when using different computers that are running under Windows XP ?

Hello
I'm currently developping an image processing algorithm using Labview 7.1 and the associated IMAQ Vision tools. After several tests, I found a weird result. Indeed, I put the labview algorithm - including the IMAQ VI on the library to get sure that I use all the time the same VI - on my memory stick and used it on two different computers. I tested the same picture (still in my memory stick) and had two very different results.
After several hours trying to understand why, I found that there were a difference between the results given by both computers at the very begining of the algorithm. Indeed, I used a JPEG file.
To open it, I first create an Image with IMAQ Create (U8). Then, I open it.
Then in my first sub-VI, I use IMAQ Cast Image to be sure that the picture is a U8 grayscale picture.
Right after that, I use the IMAQ Linear Averages. The results of this VI are different on the two computers.
I tried several time on the same picture : one computer always give me the same result but the two computers give me a different result. So there is no random variable on the results.
So my question is : Do IMAQ Cast Image or IMAQ Linear averages give different results when using different computers that are running under Windows XP ?
My bet is on IMAQ Cast Image but I'm not quite sure and I do not undestand why. The labview and IMAQ are the same on both computers.
The difference between the two computer are above :
Computer 1 :
Pentium(R) 4 CPU 3.20GHz with a RAM of 1Go. The processor is an Intel(R).
The OS is windows XP Pro 2002
Computer 2 :
Pentium(R) 4 CPU 2.80GHz with a RAM of 512Mo. The processor is an Intel(R).
The OS is windows XP Pro 2002.
If anybody can help me on this problem, it would be really helpful.
Regards
Florence P.

Hi,
Indeed it's a strange behaviour, could you send me your VI and your JPEG file, (or another file that reproduces) so that I could check this inthere ?
I'll then try to find out what's happening.
Regards
Richard Keromen
National Instruments France
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Error -1074396077 (IMAQ Vision: Incompatible image type) after running IMAQ Mask

I am attempting to process color picture of pellet. I want to exclude any particle that touches the edges of the color images. I created mask from original image and used this mask on the original color image to retain only the color particles that don't touch the boundary. The error occured when I ran the IMAQ Mask. The error message is “Error -1074396077 (IMAQ Vision: Incompatible image type)”. How can I fix it ?
I have picture and program as attached.
Attachments:
color sorter 01f.vi ‏87 KB
Red01a1.jpg ‏30 KB

Hi XuanThuy,
The IMAQ Cast function is part of the Vision Development Module (VDM), under the Image Management Palette, as indicated by this document: http://zone.ni.com/reference/en-XX/help/370281P-01/imaqvision/imaq_cast_image/. If you can't locate it and you indeed have the VDM, there may be an issue with the installation of this module. A similar issue has been encountered and resolved in this forum post: http://forums.ni.com/t5/Machine-Vision/can-t-find-IMAQ-cast-image-vi/td-p/340157. What version of the vision software are you using?

IMAQ Vision - Writing Image Files: File Format

Hi,
I want to save some images in LabView 5.1.1 - IMAQ Vision 2.2.1 acquired by
a camera. Several file formats are supported:
BMP, JPEG, PNG and TIFF
For me the PNG format seems to the most attractive one as it provides
lossy-less compression and platform independentness. But, in the manual
there is a comment which I don't understand: It says that the PNG format is
not recommend for precise gauging or inspection measurements - and that is
exactly what I want to do.
I always thought that once an image file is loaded into LabView there is no
difference regarding to the file format the images were saved in. Can anyone
explain me, what the problem of the PNG format is? Which format can you
recommend for preci
se gauging instead (BMP?)?
Thanks,
Gerd Simons

one correction:
I use IMAQ Vision 5.0 and NI-IMAQ 2.2.1.
Gerd Simons
"Gerd Simons" wrote in message
news:[email protected]..
> Hi,
>
> I want to save some images in LabView 5.1.1 - IMAQ Vision 2.2.1 acquired
by
> a camera. Several file formats are supported:
>
> BMP, JPEG, PNG and TIFF
>
> For me the PNG format seems to the most attractive one as it provides
> lossy-less compression and platform independentness. But, in the manual
> there is a comment which I don't understand: It says that the PNG format
is
> not recommend for precise gauging or inspection measurements - and that is
> exactly what I want to do.
> I always thought that once an image file is loaded into LabView there is
no
> difference regarding to the fil
e format the images were saved in. Can
anyone
> explain me, what the problem of the PNG format is? Which format can you
> recommend for precise gauging instead (BMP?)?
>
>
> Thanks,
> Gerd Simons
>
>

IMAQ Vision 5.0 - where are overlay vi's

Using IMAQ Vision 5.0 for LabVIEW, I find in the online reference overlay vi's such as IMAQ overlay rectangle, etc. I want to overlay a rectangle on an RGB image to show a region of interest in the application front panel. However I can't find any of these vi's in any of the IMAQ palettes. Where are they?

The overlay functions are new functions introduced in IMAQ Vision 6. In version 5, your options are to use IMAQ Draw or IMAQ Draw Text. These functions will allow you to type text and draw shapes on the image. The only drawback is that both are destructive overlays.
Ken Sun
Applications Engineering
National Instruments

Image processing with imaq vision with 2 webcams on the same computer

Hi,
I'm currently trying to set up 2 usb webcams (logitech quickcam for notebooks pro). I want to be able to have them both run simultaneously and do some image processing with the images that I get from both cameras with labview and imaq vision.
As of right now, I'm having trouble getting both cameras to run at the same time. Any help would be gladly appreciated. Thanks.

The USB IMAQ driver will not support running 2 USB cameras at a time (I believe it is a limitation of the DirectShow interface). You could open one camera, acuqire an image, close the reference to that camera and then do the same for the second camera.
If you need simultaneous acquisition, look at possibly moving to 1394 cameras or analog cameras.

How do I convert an IMAQ image buffer into an IMAQ Vision 'Image'?

Using NI IMAQ and IMAQ Vision with LabWindows/CVI 6.0...
I have some acquisition code that uses IMAQ img functions to set up a
triggered image acquisition and stores the image into an 1D unsigned char
array buffer.
I would now like to add code that uses the IMAQ Vision functions. The IMAQ
Vision function use an Image data type, which from what I can glean from the
..h files, is a structure.
Is it possible to convert the 1D unsigned char array image buffer to an
Image? How would I do this?
An inefficiant brute-force way would be to write the image to a BMP file
from IMAQ using imgSessionSaveBufferEx, then read the same file back in
using IMAQ Vision imaqReadVisionFile. I am hoping there is a more elegant
way to perform the conversion in memory without needing to write disk files.
Thank you,
Robert Rafuse
Etec, Inc.
tel: (978)531-5025
e-mail: [email protected]
web: http://www.etec-inc.com

Bob Rafuse wrote:
> Is it possible to convert the 1D unsigned char array image buffer to
> an Image? How would I do this?
Never mind. I found:
http://sine.ni.com/apps/we/niepd_web_display.DISPLAY_EPD4?p_guid=B45EACE3F11556A4E034080020E74861&p_node=DZ52490&p_submitted=N&p_rank=&p_answer=&p_source=External
which indicates that the img functions actually return a 2D array, so I can
use imaqArraytoImage after all.
My bad.
Bob

Setting maximum number of image buffers in MAX in IMAQ vision builder

To aquire large number of images using duncan Technologies Camera (7f/s) on IMAQ PCI 1424 i'm supposed to set the maximum number of buffer images in MAX(Measurement and Automation)in IMAQ vision builder. But i do not see the option for specifying the maximum number of image buffers under the properties of PCI 1424. Please advise.
Thanks in advance.

The setting is somewhat difficult to locate.
In MAX, select "Tools" on the main menu bar. Under that, select "IMAQ". The only option that comes up is "Max number of buffers".
Bruce
Bruce Ammons
Ammons Engineering

Are 16-bit greyscale images in IMAQ Vision True 16-bit

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