3d Lut (look Up Table) Viewer

[rumil]

Hello,

This is my first post on odforce so I would like to say hello.

In the last few months I was making a few features in my post-house (The Chimney Pot Warsaw). To have the best picture in the cinema I focused on 3D LUTs (Look Up Tables) and facility calibration. To be sure, that my new 3D LUTs are ok and to know how to change them I created a simple scene in Houdini. I called that 3D LUT viewer because it shows how this look up table looks like in 3D environment. It was very useful for me to understand what I should change in my LUT to eg. make blacks darker in the low lights or to change color space to achieve DCI (Digital Cinema Initiatives) format.

Maybe this scene will help some one to dig up in Look Up Tables.

If you will have any questions about this do not hesitate to ask me.

How it works.

I use 3DL LUTs (17x17x17) so to import it to Houdini you have to delete first rows of LUT to have only pure data. Rename this file to *.chan and browse it in CHOPS node called LUT. After that you will see a cube with 3D LUT graphical representation.

You can find in my post a scene file, an example one *.chan file and 3 renderings with 3 different LUTs.

Cheers

Kamil Rutkowski

kamilcgi@wp.pl

3D_LUT_Viewer.zip

[rdg]

Though I don't have any 3DLuts - this look fun to use.

Thanks for sharing!

Georg

[Marc]

Hey Kamil

Welcome to od[force]. And with a pretty cool first post too , thanks.. that looks really interesting.

M

[Tamis]

What are 3d LUTS

downloading downloading......

[Jason]

Very nice indeed! Thanks a million.

What might be very useful would be to turn it into an OTL and then upload to the Houdini Exchange. It can be a handy fully-contained downloadable tool with necessary promoted parms and also should become a full commercial Houdini-compatible (ie, it won't turn a commercial session into an NC session).

[rumil]

Hey,

thanks for invitation.

Tamis - 3D LUTs are text files which contains numbers describing color change. In a 3D LUT you can store any color correction from simple brightness, gamma (1D LUT) to custom color change with e.g. increasing saturation in lowlights with swapping all red areas in highlights to blue color, etc. It is very powerful tool. Everyone who works with scanned negative knows that if you want to see properly logarithmic files, you should use 3D LUT to see proper colors. Of course it is possible to apply 1D LUT or Log2Lin operator but you will never see proper colors.

So this is the idea of 3D LUT in a simple example.

cheers

rumil_

[Tamis]

Thnx rumil for that information!

were did you learn this ? are there some documents about this that you know off that are easy to understand ?

[rumil]

Hi Tamis,

I have learned it from internet. During the last time I found really good site with LUT theory: http://www.digitalpraxis.net/

Try "Technical Papers" section. You will find document concerning DI. All of this site is based on DI and LUTs are is a part of DI process.

I do not have any documents on my drive - sorry for that. Most of my knowledge is based on my experiments and tests.

Enjoy

rumil_

[rumil]

Hi everyone,

I am attaching the OTL with 3D LUT Viewer in newest version.

I added layer separation.

This is my first DA so if someone can check if it works, I will appreciate this.

Thanks for help.

rumil_

3D_LUT_Viewer.zip