4 Replies Latest reply on Nov 27, 2012 3:56 AM by mjones1978

    ACR Blacks slider problem?




      When i use the "Blacks" slider in ACR the darkest parts of the image "block up" and look very noisy. Unlike setting the black point or creating shadow clipping with the levels tool in PS, which gives a smooth effect, the black slider in camera raw seems to make the shadows crunchy and often with red pixels around the black ones.


      I use both PS5 and PS6 and on both programs i have the same "problem". I also have used ACR 6.2, 6.7, 7.0 and 7.2. All with the same effect.


      Up to ACR 7.0 the blacks slider had a range of 0-100 with the default being 5, and from 7.0 onward the slider can be set to either a plus or minus figure. In either version the default value often makes my shadows look pretty awful on screen. My question is - is this normal? In every book i read it says the blacks slider can be used ruthlessly to sett he black point but if i do that it creates a pretty blocked up result compared to the Levels black slider in PS.


      I shoot with a Canon EOS 5d mk2 and the RAW files appear to have quite noisy shadows when compared to the out of camera Jpegs which have silky smooth ones. Not sure if that is part of the problem?

        • 1. Re: ACR Blacks slider problem?
          Jeff Schewe Level 5

          You have several issues swirling around...first off, the old Blacks slider in Process Version 2003/2010 is completely different than Process Version 2012. Yes, any Blacks moves in the earlier process versions tended to really clamp the Blacks...that is now considerably different in the new PV 2012.


          So, which do you want to learn how to use?


          The Blacks slider of PV 2012 is prolly the last slider you want to use in the tone controls in the Basic panel. If you use it too early, you are not taking an optimal approach to tone mapping. There are plenty of tutorial (Adobe TV) to learn how to use the PV 2012 adjustments...if you learn how to use PV 2012, I suspect your clamped Blacks issue will go away.


          As far as the noise in the shadows, the camera JPGs get a dose of noise reduction in-camera. In ACR/LR, luminance noise reduction is set to zero (no luminance noise reduction at all). This would explain why your JPGs seem smoother than the default rendering in ACR/LR. I suggest learning how to adjust the luminance noise reduction in ACR/LR to optimize the noise in your raw captures. Some decent tutorials out there for that too...

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          • 2. Re: ACR Blacks slider problem?
            areohbee Level 6

            I don't know what you mean by "block up", but I agree: near black shadows often look noisier in PV2012 than PV2010 - part of it's "enhanced detail/visibility" in the shadows nature, I've always assumed.


            I often touch-up the near-black shadows with a noise brush and/or other settings if need be.


            Also, I agree with Jeff about not doing Blacks too early, *iff* they are in the ball-park to begin with. - *but* if they're gonna need a good hard tug before it's over, best not to wait too long for that, IMO, lest you end up having to redo everything else again afterward. - e.g. you can't set contrast right if blacks aren't in the ballpark...


            Note 2: shadow noise is sometimes worse if you shoot with intelligent contrast enabled in-camera, or for other reasons the image is under-exposed.


            PS - PV2012 clarity exacerbates noise in shadows too. And as Jeff said, you may need to add a base-coat of luminance noise reduction in Lr, at all but the lowest ISOs.



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            • 3. Re: ACR Blacks slider problem?
              Vit Novak Level 3

              You can't get the same result as from camera - both Canon and Nikon are using additional desaturation of shadows. This isn't used in adobe standard profiles. And it also isn't emulated in camera profiles for 5D mk2, so you will get more saturated shadows and, consequently, more color noise in shadows. As about blacks slider, for v4 profiles it should be 0, while for older, I found some incosistency here and asked a question about that, but didn't get any answer from Adobe people and right now I can't remember what it was and which 7.x version ...

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              • 4. Re: ACR Blacks slider problem?
                mjones1978 Level 1

                Jeff, Vit & Rob,


                Thanks or the detailed responses, i was indeed using the Blacks slider very early - i shall check out the tutorials and make better use of ACR. I had noticed if i use the tonal adjustments (curves) that the blacks slider results were much smoother. I huess i just need reassurance my system was fine and take it from there and you hav rpovided that thank you.


                Having pixel peeped the in camera JPEGS and RAW files i can see that the JPEGS are subjected to a hefty does of NR and a reduction of shadow saturation hence less banding, colour noise. It appears ACR "opens up" the shadows on a raw file whereas the in camera JPEG compresses them. Hence the noise, occasional posterization and so on on a raw file.


                Thanks again,


                Mark Jones