It is actually similar to a .csp lut.
Here is a made up lut:
Version 3
Format any
Type 3D+1D
From 0 10
To 0 1
Black 0
White 1
Length 2 11
LUT:
Pre {
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
}
3D {
0.000000 0.000000 0.000000
0.212500 0.212500 0.212500
0.715400 0.715400 0.715400
0.927900 0.927900 0.927900
0.072100 0.072100 0.072100
0.284600 0.284600 0.284600
0.787500 0.787500 0.787500
1.000000 1.000000 1.000000
}
Basically it takes a linear input with values from 0 to 10, remaps it to 0 to 1
with a curve made out of 11 steps, then applies a 2x2 cube (3d lut) that takes
all the saturation out.
Don't have Mplay here, so can not test.
________________________________
From: Ben Dickson <[email protected]>
To: Nuke user discussion <[email protected]>
Sent: Wednesday, 26 June 2013, 21:23
Subject: Re: [Nuke-users] Re: Houdini preLUTs
The HDK docs should explain the format of the prelut:
http://www.sidefx.com/docs/hdk11.0/hdk_io_lut.html
Additionally, OCIO's FileFormatHDL.cpp might be of use to clarify some
things. It is quite heavily commented, and has some test cases at the
end of the file which contain small example LUT's:
https://github.com/imageworks/OpenColorIO/blob/master/src/core/FileFormatHDL.cpp
On 27/06/13 13:42, Dan Rosen wrote:
> I don't have an OCIO environment set up. So I'd like to feed in a custom
> shaper lut file or simply copy and paste it in. Is there a command line
> way to feed a shaper lut file vs setting it in an OCIO environment? I
> don't think there is. I"ll send an example of what I've got tomorrow as
> I'm not currently in the office. It's just a matter of format in the
> shaper lut values.
>
> I'm sure it would benefit me in the log run to set up the OCIO
> environment. One small thing is that we have a custom lin2log at our
> facility. Do you have a generic Houdini lut, with a lin2log in the pre
> lut, that you could share so I could look at the formatting?
>
> Thanks,
> Dan
>
> On Wednesday, June 26, 2013, Alex - wrote:
>
> What sort of problem are you having?
> We have been using ociobakelut to create houdini.lut files with
> working 1D shapers/preluts without any issues.
>
> Your example looks pretty correct.
>
>
> On Thu, Jun 27, 2013 at 8:57 AM, Dan Rosen <[email protected]
> <javascript:_e({}, 'cvml', '[email protected]');>> wrote:
>
> Hello there,
>
> I'm looking for some help to generate Houdini linear LUTs. We
> are using ociobakelut a bit and can convert luts to Houdini
> format, but the header, specifically the log2lin Pre (LUT) is
> proving difficult. If anyone has any insight and or python that
> might be useful to share that would be much appreciated.
>
> I know that the header is something like this, but with the
> format of the Pre (LUT) part is where I'm getting tripped up.
>
> Version 3
> Format any
> Type 3D+1D
> > From 0 10
> To 0 1
> Black 0
> White 1
> Length [cube_size] [prelut_size]
> LUT:
> Pre {
> [val]
> [val]
> :
> [val]
> }
> 3D {
> [r] [g] [b
><http://www.sidefx.com/docs/hdk10.0/_r_e___o_g_l_8h.html#0f71581a41fd2264c8944126dabbd010>]
> [r] [g] [b
><http://www.sidefx.com/docs/hdk10.0/_r_e___o_g_l_8h.html#0f71581a41fd2264c8944126dabbd010>]
> :
> [r] [g] [b
><http://www.sidefx.com/docs/hdk10.0/_r_e___o_g_l_8h.html#0f71581a41fd2264c8944126dabbd010>]
> }
>
>
> _______________________________________________
> Nuke-users mailing list
> [email protected] <javascript:_e({}, 'cvml',
> '[email protected]');>,
> http://forums.thefoundry.co.uk/
> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users
>
>
>
>
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--
ben dickson
2D TD | [email protected]
rising sun pictures | www.rsp.com.au
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