Re: Use of LUTS give different results

Posted by Robert Lockwood on Dec 04, 2014; 9:57pm
URL: http://imagej.273.s1.nabble.com/Use-of-LUTS-give-different-results-tp5010726p5010774.html

Thanks, Michael, that worked.  I decided to use histoMin andhistoMax for
now.

Nate

On Thu, Dec 4, 2014 at 2:21 AM, Michael Schmid <[hidden email]>
wrote:

> Hi Robert,
>
> if you have 16-bit data and a LUT, it depends on the min & max of the
> display range of the pixels how it appears on the screen. By default, the
> display range is the full 16-bit range, 0-65535
>
> See ImageProcessor.setMinAndMax(double min, double max)
>
> In your case, with values between 15000 and 24000, just use
>
>   ip.setMinAndMax(15000, 24000);
>
>
> Michael
> ________________________________________________________________
> On Dec 2, 2014, at 23:33, Robert Lockwood wrote:
>
> > Thanks to Wayne and Jerome I have a working (up to a point) section of
> Java
> > code that creates an 16 bit gray scale imagePlus from my raw infrared
> > camera data and saves it as a PNG.  This image displays correctly in
> Fiji.
> >
> > I next load a custom LUT, 256 byte each for RBB, and save that as a PNG.
> >
> > If I load the gray scale PNG into Fiji and apply the custom LUT it
> displays
> > as I expect (the low values are in tans and the high in red to orange to
> > yellow to white).
> >
> > The other PNG, with the LUT applied in code, is mostly all red.
> >
> > For technical reasons the raw data start with DN values around 15,000+.
> > The target is a black body that I can heat to a precise temperature (I
> > don't go above 1,250 C in tests).  DN values at the high end are about
> > 22,000+ with a range less than 2^14.
> >
> > Why do the gray scale PNG with the LUT applied post processing and the
> PNG
> > with the LUT applied in code differ and what can I do about it? Is it a
> > max/min or a stretch problem?
> >
> > I can attach examples if that's allowed by the Interest Group rules.  My
> > Java code is below:
> >
> > Nate
> >
> > ImagePlus imp = IJ.createImage("Untitled", imageWidth, imageHeight, 1
> > ,imageBitsPerPix ); // 16
> > ShortProcessor ip = (ShortProcessor) imp.getProcessor();
> > short[] data = (short[]) ip.getPixels();
> > imageByteBuffer.position(0);
> > int index = 0;
> > while(imageByteBuffer.hasRemaining())
> > data[index++] = imageByteBuffer.getShort();
> > IJ.saveAs(imp, "PNG", imageFullPathName); // looks OK
> >
> > ip.setLut(Shared.getLUT());
> > imp.setProcessor("LUT", ip);
> > IJ.saveAs(imp, "PNG", imageDisplayFolderPath);
> >
> >
> > --
> > When I was 12 I thought I would live forever.
> > So far, so good.
> >
> > --
> > ImageJ mailing list: http://imagej.nih.gov/ij/list.html
>
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html
>

--
When I was 12 I thought I would live forever.
So far, so good.

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ImageJ mailing list: http://imagej.nih.gov/ij/list.html