sRGB is not 2.2 so .4545 will not make it match. at its mid point its around 2.4 but you should have a look at this if you are trying to work in sRGB and inverse. http://en.wikipedia.org/wiki/SRGB
Randy S. Little http://www.rslittle.com On Thu, Mar 8, 2012 at 12:13, Rich Bobo <[email protected]> wrote: > Simon, > > I made a linear ICC working space profile and I was able to successfully > convert my 32 bit file to 8 bit with very little shifting of values. Yea! > So, that was a "win" - thank you! The one wrinkle that I hadn't taken into > account is that when I save out the 8 bit layered TIFF file from Photoshop - > it's still in linear colorspace! And, if I do a convert to color space in > Photoshop - from linear to sRGB - I still get the same darkening as before! > So, I'll I've really done is to move the problem farther down the pipeline! > Arrgghh... Any suggestions? > > > Thanks, > > Rich > > Rich Bobo > Senior VFX Compositor > Email: [email protected] > Mobile: 248.840.2665 > Web: http://richbobo.com > > > On Mar 08, 2012, at 11:18 AM, Simon Björk <[email protected]> wrote: > > And the levels should be applied to the actual layers, not on masks. Unless > I'm misunderstanding you. > > 2012/3/8 Simon Björk <[email protected]> >> >> After, as it will make the layers blend in linear light instead of sRGB. >> The overall gamma will be the same as the sRGB viewer lut you have in >> Nuke. Although, you might introduce problems with banding as your really >> bending the colors of 8-bit. Of course you will also clamp values above 1. >> It might be better to do your compositing in sRGB space in Nuke as other >> suggested, but it's worth a try. Essentially, this would be somewhat the >> same thing as using a linear ICC profile in PS. >> >> >> 2012/3/8 Richard Bobo <[email protected]> >>> >>> Simon, >>> >>> Are you saying that the .4545 levels effect on the layer masks and the >>> overall 2.2 gamma adjustment should be done before the 32 to 8 bit depth >>> conversion or after...? >>> >>> Thanks, >>> >>> Rich >>> >>> Rich Bobo >>> Senior VFX Compositor >>> Email: [email protected] >>> Mobile: 248.840.2665 >>> Web: http://richbobo.com >>> >>> >>> On Mar 08, 2012, at 03:46 AM, Simon Björk <[email protected]> >>> wrote: >>> >>> Look here to create a linear ICC profile: >>> http://fnordware.blogspot.com/2008/05/making-linear-icc-profile.html. With >>> that set as your working space, you should be able to get correct blending. >>> >>> If you only have a couple of layers, you could try adding a Levels effect >>> and set gamma to 0.4545 to each layer. On the top of your layers you would >>> then need to set an adjustment layer with a gamma of 2.2. >>> >>> /Simon >>> >>> >>> 2012/3/8 Randy Little <[email protected]> >>>> >>>> because you are using blend modes in photoshop that do not support >>>> float math(s) AND/Or you your working space ICC is not set up right. >>>> >>>> Randy S. Little >>>> http://reel.rslittle.com >>>> http://imdb.com/name/nm2325729/ >>>> >>>> >>>> >>>> >>>> On Wed, Mar 7, 2012 at 20:43, Richard Bobo <[email protected]> wrote: >>>> > Adrian, >>>> > >>>> > Thanks for wanting to help! >>>> > >>>> > Here are the parameters: >>>> > -- CG render passes, comped and beautified in Nuke (auto work)... >>>> > -- Ultimate deliverables for client are layered 8 bit TIFF files with >>>> > alpha >>>> > out of Photoshop (different parts of vehicle)... >>>> > >>>> > In order to ease the workload, we are trying to render layered files >>>> > out of >>>> > Nuke that get loaded into Photoshop. There is some automated work that >>>> > is >>>> > done with a recorded macro/droplet in Photoshop and the end result is >>>> > our >>>> > client-ready 8 bit layered TIFF .psd file. >>>> > >>>> > It would be *perfect* if we could render out an 8 bit layered file of >>>> > some >>>> > kind from Nuke. The only reliable layered file format that I know of >>>> > coming >>>> > out of Nuke is EXR. And, I don't think Nuke will produce a layered >>>> > TIFF or >>>> > DPX that Photoshop can read properly. I could be wrong about that and >>>> > if I >>>> > am, I'd love to know how to do it! Also, EXR output does not allow 8 >>>> > bit, as >>>> > far as I can tell. So, we've tried 32 and 16 bit EXRs. >>>> > >>>> > The OpenEXR Photoshop plugin does a nice job of loading the EXR files, >>>> > either as premultiplied layers with transparency or as >>>> > unpremultiplied, >>>> > separated layers for fill and alpha. The look of the layer comp in >>>> > Photoshop >>>> > matches Nuke as long as we stay in 32 bit linear space in Photoshop. >>>> > However, changing the bit depth to 8 bit results in a general >>>> > darkening of >>>> > the image layers and a different "gamma look" to the transparent >>>> > areas. In >>>> > other words, the nice linear gradients are squashed in some areas and >>>> > not as >>>> > "spread out". >>>> > >>>> > The ProEXR manual does speak about this kind of problem and suggests >>>> > bringing in the layers unpremultiplied and using Levels adjustments on >>>> > the >>>> > layer masks only of each layer before changing the bit depth. With >>>> > some >>>> > trial and error, I have been able to find some values that will >>>> > *almost* >>>> > work. However, the levels adjustment values are not the same for each >>>> > layer. >>>> > And, it still does not look quite right. >>>> > >>>> > Photoshop *will* produce the correct result, however, *if* we choose >>>> > to >>>> > Merge the layers before doing the 32-->8 conversion - but that's not >>>> > what we >>>> > need - we need the layers... >>>> > >>>> > So, for the moment, we are going to try and see if we can live with >>>> > individual Levels adjustments for each layer in Photoshop, prior to >>>> > the bit >>>> > depth conversion. That may be the path of least resistance - but it >>>> > sure >>>> > ain't pretty! (8^P >>>> > >>>> > So, Adrian, I hope that explains things a bit better. if you have any >>>> > suggestions, I would love to hear them! >>>> > >>>> > Thanks, >>>> > >>>> > Rich >>>> > >>>> > >>>> > Rich Bobo >>>> > Senior VFX Compositor >>>> > >>>> > Mobile: (248) 840-2665 >>>> > Web: http://richbobo.com/ >>>> > >>>> > "Man has been endowed with reason, with the power to create, so that >>>> > he can >>>> > add to what he's been given." >>>> > - Anton Chekhov >>>> > >>>> > >>>> > >>>> > >>>> > >>>> > On Mar 7, 2012, at 6:24 PM, Adrian Baltowski wrote: >>>> > >>>> > Hi >>>> > >>>> > I want help or advise you something but I don't fully understand your >>>> > workflow... >>>> > You can of course make color conversion in nuke. Nuke is brilliant >>>> > software >>>> > to make such a conversions BUT.... What next?? You cannot export >>>> > layered >>>> > tiffs out of Nuke (at least not in usable form). Do you want to export >>>> > layers as separate tif files? >>>> > If you could explain your workflow then we could advise you more. >>>> > >>>> > >>>> > >>>> > Best >>>> > Adrian >>>> > >>>> > >>>> > W dniu 2012-03-07 16:33:54 użytkownik Juan Galva >>>> > <[email protected]> >>>> > napisał: >>>> > >>>> > keep us posted, please! >>>> > >>>> > On 7 March 2012 16:27, Richard Bobo <[email protected]> wrote: >>>> >> >>>> >> Thanks, Julik, Andy, Diogo and Simon for your suggestions, ideas and >>>> >> questions... >>>> >> >>>> >> After trying a number of things and reading some more about the way >>>> >> ProEXR >>>> >> and Photoshop handle things, we're going to try to make our tweaks in >>>> >> Nuke >>>> >> and let Photoshop do whatever it does. It may take a few rounds of >>>> >> tweaking >>>> >> and converting to see just what we need to do on the Nuke side to >>>> >> make it >>>> >> come out the way we want on the Photoshop end. However, it seems like >>>> >> there >>>> >> are just too many variables there. So, we'll not try to fight it... >>>> >> (8^ >>>> >> >>>> >> Thanks for your help! >>>> >> >>>> >> Rich >>>> >> >>>> >> >>>> >> Rich Bobo >>>> >> Senior VFX Compositor >>>> >> Email: [email protected] >>>> >> Mobile: 248.840.2665 >>>> >> Web: http://richbobo.com >>>> >> >>>> >> >>>> >> On Mar 07, 2012, at 07:00 AM, Simon Björk <[email protected]> >>>> >> wrote: >>>> >> >>>> >> In what application are you comparing the result of the TIFFs? Nuke >>>> >> or >>>> >> Photoshop? I believe Photoshop use linear light math when in 32bpc >>>> >> and in >>>> >> that case, the blending of layers (and brightness) will look >>>> >> different if >>>> >> you change your project to 8 or 16-bit. >>>> >> >>>> >> >>>> >> >>>> >> 2012/3/7 Julik Tarkhanov <[email protected]> >>>> >>> >>>> >>> >>>> >>> On 7 mrt 2012, at 01:51, Rich Bobo wrote: >>>> >>> >>>> >>> The problem is that we need to get 8 bit layered TIFs out of >>>> >>> Photoshop. >>>> >>> >>>> >>> I think the first problem is that the Photoshop blending is >>>> >>> profoundly >>>> >>> affected by the bit depth. >>>> >>> The second problem is that if Nuke does a 1D lookp table conversion >>>> >>> from >>>> >>> one kind of RGB to another >>>> >>> (including bit depth upgrades), Photoshop goes via Lab so what is >>>> >>> happening is more like to a 3D LUT. >>>> >>> >>>> >>> What happens in your case is that probably Photoshop is converting >>>> >>> the >>>> >>> layers first, and then the result of the blending >>>> >>> modes changes the way the images look. Maybe it's an issue with >>>> >>> layer >>>> >>> mask and front unpremultiplication and conversion. >>>> >>> >>>> >>> For me the first thing to check would be the PS profile settings for >>>> >>> 8-bit RGB. Also, where do the discrepancies occur the most? >>>> >>> Blended layer edges? Maybe your workflow needs to be related to >>>> >>> manually >>>> >>> unpremulting layers by the layer transparency and >>>> >>> preadjusting the transparency grays... >>>> >>> -- >>>> >>> Julik Tarkhanov | HecticElectric | Keizersgracht 736 1017 EX >>>> >>> Amsterdam | The Netherlands | tel. +31 20 330 8250 >>>> >>> >>>> >>> cel. +31 61 145 06 36 | http://hecticelectric.nl >>>> >>> >>>> >>> >>>> >>> >>>> >>> >>>> >>> _______________________________________________ >>>> >>> Nuke-users mailing list >>>> >>> [email protected], http://forums.thefoundry.co.uk/ >>>> >>> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >>>> >> >>>> >> >>>> >> >>>> >> >>>> >> -- >>>> >> -------------------------------- >>>> >> Stiller Studios >>>> >> Lidingö/Sweden >>>> >> >>>> >> Simon Björk >>>> >> Stiller Studios >>>> >> +46 (0)8 555 23 560 >>>> >> Ekholmsnäsvägen 40, S-181 41 Lidingö >>>> >> [email protected] >>>> >> www.stillerstudios.se >>>> >> >>>> >> find us: >>>> >> >>>> >> http://www.eniro.se/query?search_word=stiller+studios&geo_area=liding%F6&what=all >>>> >> >>>> >> >>>> >> _______________________________________________ >>>> >> Nuke-users mailing list >>>> >> [email protected], http://forums.thefoundry.co.uk/ >>>> >> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >>>> >> >>>> >> >>>> >> >>>> >> _______________________________________________ >>>> >> Nuke-users mailing list >>>> >> [email protected], http://forums.thefoundry.co.uk/ >>>> >> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >>>> > >>>> > >>>> > >>>> > >>>> > -- >>>> > >>>> > Y ella dijo: "La ilusión mueve el mundo" >>>> > >>>> > >>>> > _______________________________________________ >>>> > Nuke-users mailing list >>>> > [email protected], http://forums.thefoundry.co.uk/ >>>> > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >>>> > >>>> > >>>> > >>>> > _______________________________________________ >>>> > Nuke-users mailing list >>>> > [email protected], http://forums.thefoundry.co.uk/ >>>> > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >>>> _______________________________________________ >>>> Nuke-users mailing list >>>> [email protected], http://forums.thefoundry.co.uk/ >>>> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >>> >>> >>> >>> >>> -- >>> -------------------------------- >>> Stiller Studios >>> Lidingö/Sweden >>> >>> Simon Björk >>> Stiller Studios >>> +46 (0)8 555 23 560 >>> Ekholmsnäsvägen 40, S-181 41 Lidingö >>> [email protected] >>> www.stillerstudios.se >>> >>> find us: >>> http://www.eniro.se/query?search_word=stiller+studios&geo_area=liding%F6&what=all >>> >>> >>> _______________________________________________ >>> Nuke-users mailing list >>> [email protected], http://forums.thefoundry.co.uk/ >>> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >>> >>> >>> _______________________________________________ >>> Nuke-users mailing list >>> [email protected], http://forums.thefoundry.co.uk/ >>> http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users >> >> >> >> >> -- >> -------------------------------- >> Stiller Studios >> Lidingö/Sweden >> >> Simon Björk >> Stiller Studios >> +46 (0)8 555 23 560 >> Ekholmsnäsvägen 40, S-181 41 Lidingö >> [email protected] >> www.stillerstudios.se >> >> find us: >> http://www.eniro.se/query?search_word=stiller+studios&geo_area=liding%F6&what=all >> >> > > > > -- > -------------------------------- > Stiller Studios > Lidingö/Sweden > > Simon Björk > Stiller Studios > +46 (0)8 555 23 560 > Ekholmsnäsvägen 40, S-181 41 Lidingö > [email protected] > www.stillerstudios.se > > find us: > http://www.eniro.se/query?search_word=stiller+studios&geo_area=liding%F6&what=all > > > _______________________________________________ > Nuke-users mailing list > [email protected], http://forums.thefoundry.co.uk/ > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users > > > _______________________________________________ > Nuke-users mailing list > [email protected], http://forums.thefoundry.co.uk/ > http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users _______________________________________________ Nuke-users mailing list [email protected], http://forums.thefoundry.co.uk/ http://support.thefoundry.co.uk/cgi-bin/mailman/listinfo/nuke-users
