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
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