One more question about Iterators. Do they are multithreaded or not?Thanx Larry!I
definitely will check ImageBuf::Iterator. And do my best.Common or not, but if you'll
check some of 3D format parsers, you can find that they are by default normalize
vertices normals. And even if most 3D DCC apps do the same with normal maps inputs, and
most normal maps generator output normalized data, it still a good to have this function
in openimageio, well, just in case. :DHi, Vlad.That's probably the simplest approach
with the existing set of IBA functions, yes. Maybe there is some optimizing you can do
around the edges -- like, `mul(img,img)` may be faster than `pow(img,2.0)`, I'm not
sure, and definitely you want to use the variety of IBA functions that takes a
destination image rather than returning an ImageBuf, in order to minimize needless
buffer copying. But those obvious tricks will only get you so far.If you're doing this a
lot and it's performance critical, a better way would be to write it as a single
function that uses ImageBuf::Iterator to traverse the image and do all the operations at
once for each pixel, with no extra buffer copies. Looking at the source code to any of
the usual IBA functions that take one input image and produce one output image will
provide you with a good example to copy and change the guts to make your new function.I
don't recall anybody asking for this particular thing before, but if you think it is a
commonly needed operation, then by all means propose a PR to add this new function after
you've implemented it.On Sun, Jun 4, 2023 at 6:28 PM Vladlen Erium <v...@hdri.xyz>
wrote:What should be most efficient way to implement normalizing vector data images
(normals) using ImageBuffAlgo?For this moment I only see the way to do this in four
steps. ImageBuffAlgo::madd for [0.0,1.0] -> [-1.0,1.0]ImageBuffAlgo::pow for power of
2ImageBuffAlgo::sum_channels for vector magnitudeImageBuffAlgo::div (sec and magnitude)
to normalize vector length ImageBuffAlgo::madd for normalize to [0.0, 1.0] range.This
not only required to make so many steps but also required a lot of temporary buffers,
that for huge textures can required lot of memory. When all steps can be done per pixel
and perfectly parallelized (shaders, cuda).Maybe I missed some OIIO functions? 🤔Best
regards:VladPS: btw, looks like Google completely filter out all Larry messages if Gmail
used for subscription to this mailing list. They even not in spam folder, where mail
list messages quite often can be moved
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