Contrast Strech on Planar Image

Hi all,
How to apply a simple contrast stretch algorithm on 8bit RGB PlanarImage.
Please note that, stretch is interactive. The user will specify min and max value of histogram , by moving the slider.
Edited by: java_explorer on Jul 15, 2008 9:09 PM

Hi,
For Histogramm equalization look at the
HistogramDescriptor class of JAI.
Olek

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Photosmart C309g-m, contrast & brightness on printed images

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Thanks,
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Hi there jimjohnston,
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How to add "Contrast" to many layers (images) at once?

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A script seems like the best solution.
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How to convert a 2D array of pixels in to a grayscale planar image

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jyang, thank you very much for your response. I believe I found a different solution all together, by converting each 16-bit intensity value into an 8-bit intensity value via an intensity ratio (ie: divide each intensity by the maximum and multiply by 256). The attachment shows the new program.
Attachments:
mod_image.vi ‏2004 KB

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First: I'm new in vision processing.
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And of course, the rambling about IMAQ image pointers isn't relevant. (Skip all IMAQ.)
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"Wiebe@CARYA" <[email protected]> wrote in message news:[email protected]...
Hi,
If I understand correctly, you just want a gradient screen to rotate, and to be able to adjust it's contrast.
This can be done a lot easier without an image. If you use OpenGL, you can just draw two triangles with there color set correctly. (You'd be able to make nice rainbow pictures as a bonus.)
An C/C++ application, or dll, could be made in a few hours by someone experienced with opengl and c++. You could even create an opengl window, and control it with LabVIEW. In other opengl applications there are some practical problems, but some might not matter to your application. Biggest problem is getting feedback (mouse clicks, close, move, resize window etc.) from the OpenGL window to LabVIEW.
Opening a opengl window, rotating a few polygons, adjusting color, closing window certainly doable.
Regards,
Wiebe.
"ibstein74" <[email protected]> wrote in message news:[email protected]...
Hi Wiebe, I have a fixed image, created before with array functions, that contain a pure linear greyscale gradient (left side: white / right side: black). I used this image to control a "spatial light modulator". This device is connected to the second DVI graphic card output. The main task of the "spatial light modulator" is to shift the local phase of the reflective light. It works as an spatial resolved "adaptive mirror".  The local phase shift correspondes directly to the applied grey level of the image. To change the direction in both dimensions of the reflective light I need to rotate this image (= rotate the phase wedge) Thereby the contrast can adjust the absolute angle of reflection.After I had calculated my greyscale gradient image and applied it to the second DVI output, I want only control the contrast and rotation. I think the graphic card function are very fast. But I have to control the graphic card directly per DLL or C-function node. It must be possible because I can tune the contrast and adjust the rotation manually with the nvidea driver in the windows system manager. I'm  waiting for a couple of weeks of an answer from nvidea but it seems that contrast and rotation of an 2D-image is not a real problem for these 3-D guys. :-(I hope of an answer or new ideas.Ivo Buske

Unsigned 16-Bit Image Brightness Contrast

Hello, Everyone
I have Unsigned 16-Bit Image , I want to change the brightness & Contrast of this Image.
I dont found any VI in LabVIEW to do that with this format (there is BCG but only for 8-Bit).
I found this link for that issue:Adjusting Brightness and Contrast for 16-Bit Image
So, I used the Operators function to do that. but i dont know if the order of that functions is sensitive or NOT. see Picture
and did i realy need to use Subtract operators and Divide operators .
Best wishes
Alzhrani

Hi Al-Zahrani,
I don't believe that it matters whether you do brightness or contrast first. You can verify this by looking at a picture using both methods you showed below. However, when I did this, I did not see much of a difference and believe that you can place either brightness or contrast first. Also, you will need to include the math functions in order to perform the image processing you are trying to do. Hope this helps!
Mychal F
Applications Engineer
National Instruments

Image processing from .txt file onto an intensity graph

I am doing a mini project in my class and I was wondering if anyone could help me. It about image processing but I am bit stuck.
Heres the idea:
"An image is really nothing more than a 2D array of data. The value of every element in the array corresponds to the brightness of the image at that point.
In this project you will create a VI which loads a 2D array of data and then displays it on the screen using the Intensity Graph. Three example files (boats.txt, gordon.txt and parrot.txt) are available on the module webpage that you can use. However, you can also use any other black and white image you like, but will need to convert it to a “text image” first. To do this you can use some software called “ImageJ” which is available on the computers and is free to download.
You can vary the brightness of an image by adding the same value to every element in the array.
The contrast of an image is adjusted by multiplying every element in the array by the same value. Using numerical controls and simple array mathematics, you should adjust the brightness and contrast of your displayed image.
Some other ideas that you could try with image manipulation are:
o Invert an image (change black to white and white to black)"
First I am having problems putting my picture onto the graph. It is in the write file but the colours are not correct and the image has rotated 90 degrees. I will upload my VI so far when I get back onto my computer.
Would really appricate the help! Thank you for reading

Hi charlthedancer,
Here is an example to get you started.
Kind regards,
GajanS
Attachments:
Test.vi ‏14 KB

Image Processing Performance Issue | JAI

I am processing TIFF images to generate several JPG files out of it after applying image processing on it.
Following are the transformations applied:
1. Read TIFF image from disk. The tiff is available in form of a PlanarImage object
2. Scaling
     /* Following is the code snippet */
     PlanarImage origImg;
     ParameterBlock pb = new ParameterBlock();
     pb.addSource(origImg);
     pb.add(scaleX);
     pb.add(scaleY);
     pb.add(0.0f);
     pb.add(0.0f);
     pb.add(Interpolation.getInstance(Interpolation.INTERP_BILINEAR));
     PlanarImage scaledImage = JAI.create("scale", pb);3. Convertion of planar image to buffered image. This operation is done because we need a buffered image.
     /* Following is the code snippet used */
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     bufferedImage = bufferedImage.getSubimage(artcleX, artcleY, 302, 70);The performance bottle neck in the above algorithm is step 3 where we convert the planar image to buffered image before carrying out cropping.
The operation typically takes about 1120ms to complete and considering the data set I am dealing with this is a very expensive operation. Is there an
alternate to the above mentioned approach?
I presume if I can carry out the operation mentioned under step 4 above on a planr image object instead of buffered image, I will be able to save
considerable processing time as in this case step 3 won't be required. (and that seems like the bottle neck). I have also noticed that the processing
time of the operation mentioned in step 3 above is proportional to the size of the planar image object.
Any pointers around this would be appreciated.
Thanks,
Anurag
Edited by: anurag.kapur on Oct 4, 2007 10:17 PM
Edited by: anurag.kapur on Oct 4, 2007 10:17 PM

It depends on whether you want to display the data or not.
PlanarImage (the subclass of all renderedOps) has a method that returns a Graphics object you can use to draw on the image. This allows you to do this like write on an image.
PlanarImage also has a getAsBufferedImage that will return a copy of the data in a format that can be used to write to Graphics objects. This is used for simply drawing processed images to a display.
There is also a widget called ImageCanvas (and ScrollingImagePanel) shipped with JAI (although it is not a committed part of the API). These derive from awt.Canvas/Panel and know how to render RenderedImage instances. This may use less copying/memory then getting the data as a BufferedImage and drawing it via a Graphics Object. I can't say for sure though as I have never used them.
Another way may be to extend JComponent (or another class) and customize it to use calls to PlanarImage/RenderedOp instances directly. This can hep with large tiled images when you only want to display a small portion.
matfud

How can I merge two TIFF images in one...?

I need some help please, I am looking for a way to "resize" black & white single TIFF images.
The process I need to do is like cutting a small image and paste it over a new blank letter-size image (at 300 dpi), like a template.
Or better yet, is there a way to do something like this...?
Open image...
image.*width* = 2550;
image.*height* = 3300;
image.save();Some APIs and topics in the internet do or talk about resizing, but the final images get stretched or shrinked and I need them not to do so at all.
Also, I do not need to display the images, only to get the TIFF images processed and saved back to a file.
How can I do this with Java and JAI? Unfortunately I am almost new to this and I don't know how difficult it might be to deal with images.

If 2550 x 3300 isn't the original aspect ratio of the image, then the image is going to looked streched or shrinked in at least one dimension. There is no way around that. It would be like resizing a 2 pixel by 2 pixel image into a 3 pixel by 6 pixel image. The image would look like it's height shrunk or it's width stretched. Had I resized it to 3 pixels by 3 pixels or 6 pixels by 6 pixels, though, then it wouldn't look shrunken or streched.
Open image...
image.*width* = 2550;
image.*height* = 3300;
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read(File input)
read(ImageInputStream stream)
read(InputStream input)
read(URL input) You can use which ever method you want. But first you need to install [JAI-ImageIO|https://jai-imageio.dev.java.net/binary-builds.html]. The default ImageReaders that plug themselves into the ImageIO package are BMP, PNG, GIF, and JPEG. JAI-ImageIO will add TIFF, and a few other formats.
The downside is that if clients want to you use your program on their machine then they to will need to install JAI-ImageIO to read the tiffs. To get around this, you can go to your Java/jdk1.x.x_xx/jre/lib/ext/ folder and copy the jai_imageio.jar file (after you've installed JAI-ImageIO). You can also obtain this jar from any one of the zip files of the [daily builds|https://jai-imageio.dev.java.net/binary-builds.html#Daily_builds]. If you add this jar to your program's classpath and package it together with your program, then clients won't need to install JAI-ImageIO and you'll still be able to read TIFF's. The downside of simply adding the jar to the classpath is that you won't be able to take advantage of a natively accelerated JPEG reader that comes with installing JAI-ImageIO (instead, ImageIO will use the default one).
*2)* Once you've installed [JAI-ImageIO|https://jai-imageio.dev.java.net/binary-builds.html] and used ImageIO.read(...), you'll have a BufferedImage. To resize it you can do the following
BufferedImage newImage = new BufferedImage(2550,3300,BufferedImage.TYPE_BYTE_BINARY);
Graphics2D g = newImage.createGraphics();
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g.drawImage(oldImage,0,0,2550,3300,null);
g.dispose();Here, I simply drew the old image (the one returned by ImageIO.read(...)) onto a new BufferedImage object of the appropriate size. Because you said they were black and white TIFF's, I used BufferedImage.TYPE_BYTE_BINARY, which is a black and white image. If you decide to use one the BufferedImage types that support color, then a 2550x3330 image would require at least 25 megabytes to hold into memory. On the other hand, a binary image of that size will only take up about one meg.
I specified on the graphics object that I wanted Bilinear Interpolation when scaling. The default is Nearest Neighbor interpolation, which while fast, dosen't look very good. Bilinear offers pretty good results scaling both up or down at fast speeds. Bicubic interpolation is the next step up. If you find the resized image to be subpar, then come back and post. There are a couple of other ways to resize an image.
Note, however, if 2550 x 3300 is not the same aspect ratio as the the TIFF image you loaded, then the resized image will look shrunk or stretched along one dimension. There is absolutely no way around this no matter what resizing technique you use. You'll need an image whose original dimensions are in a 2550/3300 = .772 ratio if you want the resized image to not look like it's streched (you can crop the opened image if you want).
*3)* Now we save the "newImage" with the same class we read images with: ImageIO . It has these static methods
write(RenderedImage im, String formatName, File output)
write(RenderedImage im, String formatName, ImageOutputStream output)
write(RenderedImage im, String formatName, OutputStream output)You'll suply the resized BufferedImage as the first parameter, "tiff" as the second parameter and an appropriate output for the third parameter. It's pretty much a one line statement to read or write an image. All in all, the whole thing is about 7 lines of code. Not bad of all.
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Image quality degrades in published swf

I've built a Flash site for a freind who is a photographer.
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I tried saving as a png, but I got the same result. It's like
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