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| I'm working with Alexa footage at the moment, but I wasn't 100% sure by what you meant by 'inverse'. But I think I've got it now. Basically you've downloaded a LUT to convert the Arri LogC format into a rec709 colourspace to work with in AE. Now you need to convert your renders back to the original Arri LogC colourspace? If that's it then I don't know how you can do it inside After Effects. The Arri LUT converter only creates LUTs that go one way. Can you export a different format - can you use the Cineon converter to provide Cineon Log files instead of Arri Log files? Not sure if other software such as Nuke can do this, you might have to render out 32bit dpx or exr and have them converted back to Arri LogC in a different package. -Chris -----Original Message----- From: Byron Nash [mailto:byronnash@gmail.com] Sent: Friday, February 3, 2012 01:25 PM To: 'After Effects Mail List' Subject: Re: [AE] Inverse a LUT? That's what I'm doing, and it works great until you have to put a piece of footage or a graphic in there that has a different color space. What we are trying to do is deliver a shot to color correction that does not have the LUT applied. On Thu, Feb 2, 2012 at 8:52 PM, Chris Biggs <christopher.biggs@gmail.com>wrote: > I apply my LUTs to an Adjustment layer on top of my comp, then make it a > guild layer, as to not render out > no need to reverse then. > > > On Thu, Feb 2, 2012 at 12:51 PM, Byron Nash <byronnash@gmail.com> wrote: > >> It's a 3D LUT from the Arri site, LogC2Video_Rec709. >> >> >> >> On Thu, Feb 2, 2012 at 3:13 PM, Brendan Bolles <brendan@fnordware.com>wrote: >> >>> It depends on your LUT. If it's a 3D LUT, then it can not be inverted >>> in general. 1D LUTs can often be inverted. LUT Buddy has an invert button >>> that will be enabled when the LUT is invertible. >>> >>> In the 3D LUT case, imagine you had a LUT that was used to turn your >>> image black and white (desaturate). As you know, no color operation could >>> hope to magically restore the color once it had been taken out. So that's >>> a clue as to why 3D LUTs can't generally be inverted. >>> >>> If you created your 3D LUT using a series color corrections, your best >>> hope is to try to apply them in reverse with inverted settings. You could >>> then make a LUT of that operation to be your inverted LUT. >>> >>> But usually you just try to come up with something close or deal with it >>> on a case-by-case basis. >>> >>> >>> Brendan >>> >>> >>> >>> On Feb 2, 2012, at 11:09 AM, Byron Nash wrote: >>> >>> > I was wondering if there is a way to inverse a LUT? I'm applying an >>> Arri Alexa LUT to some footage for VFX work. Some of the elements are >>> graphics that need to maintain their color with and without the LUT. We >>> have been using a LUT on an adjustment layer and then turning it off before >>> rendering it. That way our VFX should be in the correct ranges for Color >>> Correction. This works fine for source footage but as soon as you need to >>> put a logo in there it gets weird. I'd like to be able to put a reverse of >>> the LUT on the logo/graphics and keep all that under the Adjustment layer. >>> In the past we have just sort of used levels and curves to approximate the >>> graphics with some success. But I'd like to do it the "right" way. >>> >>> >>> +---End of message---+ >>> To unsubscribe send any message to <ae-list-off@media-motion.tv> >>> >> >> > > > -- > --------------------------------------- > R.Christopher Biggs > Digital Ronin > |
