Re: [Openexr-devel] channel configurations and types

[Florian Kainz]

When you read an image file, the library will automatically
convert from the data type in the file to the data type in
the frame buffer.  You can read a file with half data into
a frame buffer of type float.

When you write a file, the library will not convert between
data types.  The type in the file must match the type in the
frame buffer.

You don't have to worry about the order in which the channels
are stored in the file.  The FrameBuffer object describes
the memory location where you want the data for each channel
to be stored.  When you call InputFile::readPixels(), the
library retrieves the data from the file and stores them in
the locations specified by the FrameBuffer; how the data
are stored in the file is irrelevant.  (The order in the file
is fixed and unlikely to match your frame buffer's layout.)

Florian



darby johnston wrote:
> Hi,
>
> I had a question about reading exr files with your
> library; in the documentation it mentions that if your
> framebuffer object has channels that don't match the
> ones in the file, the library gracefully handles that
> and fills them with a default value. That's cool. I
> was wondering if there were any other automatic
> conversions that happened? Say I have an exr file that
> lists channels ABGR of type half; if I set my
> framebuffer to be RGBA of type float, can the library
> automatically reorder the channels and do the type
> conversion?
>
>
> Thanks, Darby
>
>
>
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