[Insight-users] PNG from ITK

[Miller, James V (Research)]

We produce PNG images frequently from ITK without any issues viewing 
them in other packages. I just downloaded a demo of Amira and loaded some
PNGs that were written by ITK without any issues.

Are you writing 8 bit or 16 bit PNGs?  Many image viewing applications 
do not view 16 bit PNGs well.  This can be exacerbated when you accidently 
save 8 bit data in a 16 bit PNG. In this case, the image will appear very 
very dark because the image is only using 8 bits of the 16 bit dynamic
range. 
You can recover somewhat by adjusting the contrast and brightness of the
image
in your image viewer.  Another alternative is to rescale the intensities
before ITK writes the PNG file.

Jim



-----Original Message-----
From: David Macias Verde
[mailto:david.maciasverde at gobiernodecanarias.org]
Sent: Monday, April 12, 2004 3:49 AM
To: Insight-users
Subject: [Insight-users] PNG from ITK


Hi all:

When applying, for instance, a Canny Edge Detector over a certain PNG
image, and I give the result the same PNG format, why do I have troubles
when trying to read that PNG image with the well known Amira software or
even from VTK using vtkPNGReader? It happens with all the result images
from any ITK algorithm related (i.e., Danielsson DM, etc.)

I have realize that if I edit that image into another graphic tool, like
GIMP, and I overwrite it, then the file is readed without any trouble.

Thanks,

David Macias-Verde
Hospital de Gran Canaria Dr. Negrin


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