Re: [Openexr-devel] channel configurations and types

[Florian Kainz]

darby johnston wrote:
> --- Florian Kainz <address@hidden> wrote:
>
> > 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.
>
> Great! That makes things easy...
>
> > 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.
>
> Out of curiosity, why do the conversion for reading
> but not for writing?

When you write an image, you know the data types in your frame
buffer, and making the data types in the file match shouldn't
be a problem.

When you read an image, you have no control over the data types
in the file.  If the file doesn't contain what you expect, you'd
either have to change the type of your frame buffer or convert
the pixel data to match your frame buffer.  Both alternatives are
rather inconvenient.  The library tries to be helpful by converting
the data for you.