http://imagej.273.s1.nabble.com/macro-convert-calibrated-value-to-raw-pixel-value-tp5022651p5022652.html
for the processing of whole images. Please have a look at:
v1-v2 to v3. For example, changeValues(0,5,5) changes all pixels less
blue pixels in an RGB image to red. In ImageJ 1.52d or later, use
> I decided to learn a bit about the macro language (usually I write everything in Java).
>
> To start with, I thought I would write something simple. Note that this is an exercise in
> techniques.
>
> I've hit a snag. I was trying to convert a calibrated 16-bit image to an 8-bit version, by processing it
> pixel-by-pixel. Motivated by a previous question here, I wanted to set all pixels < 0.0 to 0,
> all pixels in [0.0,10.0) to 50, those in [10.0, 20.0) to 100 ....etc. Finally, all pixels with calibrated
> values > 40.0 should be set to 255.
>
> First, I tried going from a source image to a target image. But...this seemed painfully slow because of the need(?)
> to constantly selectImage() on every getPixel() and putPixel().
>
> So...I switched to doing it in place. This was speedy enough, but I ran into an issue with calibration.
>
> To categorize the pixels, I wanted calibrated values. OK - I found getValue(x,y) and that was fine. But...now
> I need to WRITE a calibrated value. I can't find a function to do that. putPixel(x,y,value) seems to accept raw pixel values.
> I found a method to convert raw pixel values to calibrated values, but not the other way around.
>
> Below is the current state of my floundering. All hints gratefully accepted. But please - don't try to tell me how to
> perform the high-level task easier. It's just a warm-up exercise to become familiar with all the tools.
>
> Note that I have commented out some lines at the end - these show what I intend to do eventually. But, right now I can't get correct calibrated values written to the image.
>
> I would also be interested in a reasonable way to do this without modifying (or copying) the original source image). It seems to me to be cleaner to write the new pixels to a new target image. But, that appears to be r e a l l y s l o w. (or, I don' know how to do it correctly)
>
> Be kind...
> ====================================================================================
> function sixBins(pixelIn){
> if(pixelIn <= 0.0)
> pixelOut = 0*5;
> else if(pixelIn <= 10.0)
> pixelOut = 10*5;
> else if(pixelIn <= 20.0)
> pixelOut = 20*5;
> else if(pixelIn <= 30.0)
> pixelOut = 30*5;
> else if(pixelIn <= 40.0)
> pixelOut = 40*5;
> else if(pixelIn > 40.0)
> pixelOut = 255.0;
> return pixelOut;
> }
>
> orig = getImageID();
> title = getTitle();
> w = getWidth();
> h = getHeight();
>
> print(title + " is " + w + "x" + h);
>
> for(row=0;row<h;row++){
> for(col=0;col<w;col++) {
> pixelIn = getValue(col,row); // gives correct calibrated values!
> pixelOut = sixBins(pixelIn); // appears to work fine
> setPixel(col,row,pixelOut); // does not work if the image is 16-bit calibrated
> print(pixelIn + " -> " + pixelOut); // really verbose debugging
> }
> }
>
> run("Histogram");
> // selectImage(orig);
> // setMinAndMax(0,255);
> // run("8-bit");
> // selectImage(orig);
> // run("Histogram");
> ====================================================================================
> --
> Kenneth Sloan
>
[hidden email]
> Vision is the art of seeing what is invisible to others.
>
> --
> ImageJ mailing list:
http://imagej.nih.gov/ij/list.html>