Using IMAQ Cast Image to convert 16 bit to 8 bit image.

I am trying to convert a 16 bit image to a bit image, and I am using IMAQ Cast Image. I am wondering what I am supposed to wire into the # of shifts? When I use NI Vision Assistant it asks I can convert by the adjust dynamic method. Does anyone know how to do this with IMAQ Cast Image? Thank you in advance.

The number of shifts is the number of bits that will be chopped (in the dark regions) from the initial image to fit into 8 bits.
For instance, if you have a 10 bit image, compressing into an 8 bit image will obviously introduce some losses. You can decide to loose information either in the "whithe" parts or in the "black" parts of the image.
With #shifts = 0, the two most significant bits will be lost, so the whitest parts of the image will be uniformely white, but the darl grey levels will be preserved.
With #shifts = 2, the two least significant bits will be lost, preversing the whitest parts grey variations, but losing the subtilities in the darkest parts.
With #shifts = 1, a single bit is lost on either sides...
Chilly Charly (aka CC)
E-List Master - Kudos glutton - Press the yellow button on the left...

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Using IMAQ create, set-up, acquire and windraw to save image without color map

Hi,
Attached is my VI (using labview 8.5) and am not sure where it is getting the color info from, but it saves the image as jpeg/bmp/tiff with colormap (confirmed by imread in matlab). Can someone help me save these images without colormap info.
Thanks
Attachments:
HL Grab with two boards and SONY XC55_Images.vi ‏166 KB

Hi Maverick269,
I noticed that you posted this question over on the Machine Vision forums as well. That will definitely be a better place to get this question answered, so let's work on the issue over there :
http://forums.ni.com/t5/Machine-Vision/Using-IMAQ-create-set-up-acquire-and-windraw-to-save-image/m-...
In the future it helps us stay organized if we limit each issue to a single thread.
Cheers,
Andy C.
Applications Engineer
National Instruments

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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16 bit vs 8 bit

I have a Nikon D50 and I typically shoot it in Raw Mode.
I have been playing with several work flows. I love working in layers, but if I uncheck all the RAW enhancements on import and leave it in 16bit mode, I cannot use the layers until I convert it to 8 bit.
I read somewhere that leaving it in 16 bit mode for auto-levels and auto-color correction is a good idea.
I usually try this and then convert to 8 bit to do some finishing (reduce noise, unsharp, adjust skin tone).
Is this consistent with what others have found? Or do you prefer to use 8 bit mode right off (is the difference not that huge)?

I agree with Barbara, and agree to disagree with straight conversion to JPEG in almost any case, but see the point that if you aren't taking advantage of RAW, you are letting some process decide for you -- one that can't see the image. However, in Elements 4, you still have the potential to make limited changes in 16-bit, so letting the camera convert to JPEG isn't the best option, even if you don't make corrections in the dialog.
Unchecking the boxes isn't enough for working with the RAW plugin. You want to move the sliders about to try some balance and variations of tone. the dialog tries to guess for you by looking at the weighting of capture information, but in many exposure situations it will not produce the best result. You can make some changes to make the most of the capture information before moving to Elements--and continuing to improve the image.
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http://www.betterphoto.com/photocourses/RIC01.asp

Problem using IMAQ Array to Color Image vi

I am doing some pixel manipulation & while going from an image to an Image Pixels (U64) array using IMAQ Color Image to Array VI I cannot see the image once it is modified.
I am...
1) converting the image to the 64 bit pixel data using IMAQ ColorImage to Array.vi
2) doing the manipulation
3) converting back to an image using the IMAQ Array to ColorImage.vi using the 64 bit input.
What I get is...
1) a black image with data behind it... meaning... if I take the magnifier tool and go to the approximate locations of my image where I expect to find the manipulated data, it is there.
2) cast that image to a 32 bit image & still get a black image for the output. The data however is no longer there and appears to have been stripped.
3) no error's out of any VI's...
TIA

With Vision 2009 situation is not better.
It happened because U64 image displayed in full scale. So, if you have full range of intensities (from 0 to 65535), then you can see something. But if your intensities in small range, for example, 0...255 in all channels, then you will see black image.
Feel differences:
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What does the IMAQ Cast Image VI do exactly?

Hi everyone,
I want to convert a RGB image to grayscale. By now I can do this, using the IMAQ Cast Image VI. But now I was wondering what exacly does this VI do? How does it make a grayscale image from the RGB image? What is happening under the hood?
Hope someone can tell me, since I really can't find it. Thanks in advance ^^.
Solved!
Go to Solution.

For each type conversion there is specific operation. In your case The VI sets the destination value to the average of the three color components of the source.
For more:
http://zone.ni.com/reference/en-XX/help/370281P-01/imaqvision/casting_images/
Thanks
uday,
Please Mark the solution as accepted if your problem is solved and help author by clicking on kudoes
Certified LabVIEW Associate Developer (CLAD) Using LV13

I want to convert pictures to 1 bit image

dir sir;
i want to make a programe by it i want to upload image real image and then it converted it for 1 bit image ;
can i use java to do that?
and if soo what method and package and function helps me to do that .
if you can provide me with simple code i will be thankfull.
beast regards.

Hi,
if you have vision, you could use the functin IMAQ Image to Array to have a 2D array of the pixel values.
You can then compare pixel by pixel; if your images come from a camera, I would recommend to set a treshold of acceptance.
This is a time consuming solution anyway.
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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.

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Hi,
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While I feel your comment doesn't directly address my question, why I am worrying is this.
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Can I use QuickTime Pro to convert a series of JPEG images into a QT (uncompressed) movie? Thanks...
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http://www.apple.com/quicktime/tutorials/slideshow.html
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Using IMAQ Cast Image to convert 16 bit to 8 bit image.

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