Re: 16-bit gray PNG write broken?

Posted by Wayne Rasband on
URL: http://imagej.273.s1.nabble.com/16-bit-gray-PNG-write-broken-tp3695138p3695139.html

On Sep 9, 2008, at 1:48 PM, G. Jehle wrote:

> Hi everyone,
>
> I'm running ImageJ 1.39u on Ubuntu GNU/Linux (x86_64).
>
> Whenever I try to save a simple '16-bit grayscale' image
> as PNG, ImageJ saves a '8-bit/color RGB' image instead.
>
> I generated a 16-bit gray PNG using Matlab.
> Opening the PNG in ImageJ; works just fine with ImageJ
> recognizing the file as 16-bit gray, all values look ok.
>
> However, using 'File > Save As > PNG...' on the very
> file just opened results in a '8-bit/color RGB' PNG to be
> saved.
>
> Any ideas to why this might happen?

ImageJ 1.41d and later saves 16-bit and 32-bit images as 8-bit PNGs.
Earlier versions saved as RGB. ImageJ converts to 8-bits when saving in
PNG format so that the images are more likely to display correctly in
other applications. Save in TIFF format if you need to preserve 16-bit
or 32-bit values.

-wayne