[vtkusers] 24bit PNG writing

[Jim Geach]

> That should work. So are you saying the image stored in the file
> displays as grayscale?

no, it's colour, but the depth is only 8 bits per pixel.

> On Mon, Nov 14, 2011 at 2:42 PM, Jim Geach <jimgeach at physics.mcgill.ca> wrote:
>> 
>> I'm using a vtkFixedPointVolumeMapper to volume render a data cube, which I want to colour with a look-up table containing 2^24 colours (presumably this is possible -- i've been using 256 element look-up tables until now).
>> 
>> Then I've been using RenderLargeImage / WindowToImageFilter to write a large PNG... however the output image is always 8bit per pixel. I think I can access the RGB values of the displayed image directly and then write these to a PNG myself, but I'd like to use the inbuilt ImageWriter if possible.
>> 
>> On 2011-11-14, at 2:25 PM, Bill Lorensen wrote:
>> 
>>> I believe if the input data is 3 component unsigned then you can write
>>> it. But are you saying the data is a single component 24-bit integer?
>>> 
>>> On Mon, Nov 14, 2011 at 1:05 PM, Jim Geach <jimgeach at physics.mcgill.ca> wrote:
>>>> 
>>>> Is it possible to write a 24bit PNG using the vtkPNGWriter? I'm using a palette with >256 colours and would like to be able to save the render to an image file.
>>>> 
>>>> Thanks, Jim
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