Re: [Vxl-maintainers] RGBA or ARGB?

[Gehua Y. <yan...@gm...>]

On Sun, Nov 13, 2011 at 6:26 PM, Ian Scott <sc...@im...> wrote:
> On 13/11/2011 22:44, Gehua Yang wrote:
>>
>> a)  Can we make it a rule that the ordering of color is always RGB or
>> RGBA when calling vil_save or vil_load?
>>
>>    If yes,  I can make changes to vil_bmp so that it returns the image
>> view with planes in this order (by re-ordering the pixel color
>> values).
>
> That seems like the sane approach. Anything else will lead to significant
> extra complexity for the user. I would however be slightly more careful in
> delimiting the rule, we don't to catch users who are loading non-RGB
> multiplane data. And we don't want to have to reorder memory unless
> necessary.
>
> for example:
> "If you load or save an RGB or RGBA multiplane image, from a format that
> explicitly handles RGB(A) images, then you can assume that the planes are
> 0-Red, 1-Green, 2-Blue (and 3-Alpha). However, this does not guarantee that
> Green, etc. comes after Red in memory."
>
> Ian.
>
>
Agreed.  For example, after loading a RGB image in bmp format, the
plane_step will still be -1.

Gehua.