Dear Herbie,

I don’t know how to save a 16-bit image with a LUT in PNG format. ImageJ uses 
the Java ImageIO.write() method to save in PNG format but this method requires 
a BufferedImage and there isn’t a TYPE_USHORT_INDEXED image type, only 
TYPE_USHORT_GRAY. 

-wayne

> On Aug 10, 2024, at 5:22 AM, Herbie <[email protected]> wrote:
> 
> Dear specialists and Wayne,
> 
> maybe it's a property of the PNG-file format that a 16bit image with 
> monochrome LUT is saved as 8bit with such a LUT.
> 
> Below please find a demo macro that saves and re-opens a 16bit image with 
> green LUT in TIF-format and PNG-format as well as without LUT in PNG-format.
> 
> //
> dir=getDir("temp");
> newImage("Test","16-bit ramp",192,192,1);
> save(dir+"test.png");
> run("Green");
> save(dir+"testLUT.tif");
> save(dir+"testLUT.png");
> close();
> open(dir+"testLUT.tif");
> open(dir+"testLUT.png");
> open(dir+"test.png");
> run("Tile");
> exit();
> //
> 
> Of course the TIF-image with LUT and the PNG-image without LUT open as 16bit 
> images, not so the PNG-image with LUT that opens as 8bit image.
> 
> Is this a property of the PNG-file format?
> Are there ways to get around the implicit 8bit-conversion?
> 
> Thanks for possible insights
> 
> Herbie
> ::::::::::::::::::::::::::::

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