On Jun 12, 2012, at 11:54 AM, Stefan Stavrev wrote:
> 1. "If you have an ImageBuf::Iterator<BUFTYPE,float>, then *iterator will
> always be float that you can just use."
>
> Will it always be in range 0-1?
No. It will be the float conversion of whatever the input is. Certainly for
half or float image files, it could be anything. (For anybody doing
compositing, half is increasingly the usual case.)
> 2. Since m_spec_valid and m_pixels_valid are protected I need to add a method
> in imagebuf.h.
>
> bool uninitialized () const { return ! m_spec_valid && ! m_pixels_valid; }
>
> Is "initialized" negation of "uninitialized"? In this case initialized would
> mean:
>
> m_spec_valid || m_pixels_valid
Let's do it as "initialized" and then you can ask for "if (!
ib.initialized())". I think that's more clear. Or you could do both, I don't
mind.
>
> 3. "A channel with a labeled alpha channel should be assumed to be correct,
> use it (any number of non-alpha channels are ok, as long as they match
> between the two input images)."
>
> Hmm, ok I think I got it this time. So we handle the case of alpha channel
> not specified, only for the two cases where number of channels is 3 or 4? In
> other words, for number of channels 1,2,5,... fail if alpha channel is not
> specified for both images? Don't assume any channel is alpha, don't assume
> alpha is 1 everywhere.
I think that is right.
If there are 6 channels and none are alpha, it's anybody's guess whether alpha
might be channel #3 (as if it were RGBA??), or if it's the last channel
(XYZPQA), or if none are alpha. Just give up in that case.
But if it's 3 or 4 channels and unlabeled, it will almost always be RGB/RGBA.
--
Larry Gritz
[email protected]
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