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Photo Retouching "Improving" photos, post-production, correction, etc.

Calculations???

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  #1  
Old 09-29-2008, 01:57 PM
Mike Kalcevic Mike Kalcevic is offline
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Calculations???

Unless I'm off base, I remember reading somewhere about using the Calculations command when retouching skin, but I can't really find any good explanation as to how and why...

Anyone feel like giving me the 10 cent tour on this, or at least point me in a direction to good tutorials on using Calculations for skin retouching??
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Old 09-29-2008, 02:45 PM
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Daviskw Daviskw is offline
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Re: Calculations???

Hi Mike...I'm sure Chris will be alone soon with some much better advice. I often use apply image when making masks. Calculations does essentially the same thing except it saves you steps by allowing you to use two channels and output the result to a third channel.

Dan Margulis often uses and explains calculations in his books.

Butch
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Old 09-29-2008, 04:41 PM
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cricket1961 cricket1961 is offline
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Re: Calculations???

Hey Mike

Calculations would be a bit difficult to use for retouching skin. It would be a blending of different channels to even out blemishes and then incorporate that into the existing channel/s. For someone not familiar with Calculations it can be time consuming figuring out the best combo's and blend mode to use.

But it could be done. : )

But a 10¢ tour would be a bit short on providing the answers you are looking for. It really depends a lot on the skin coloring, brown, white, tan, etc. And then fixing shadows etc would involve a bit more.

In PS David, it went like this:

calculations - to apply image - to channel mixer.

experience to newbie (not necessarily powerwise, just familiarity)

Chris
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Old 09-29-2008, 04:45 PM
Mike Kalcevic Mike Kalcevic is offline
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Re: Calculations???

Thanks Chris,

Do you have any book recommendations that I can check out to learn this better?
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Old 09-29-2008, 05:11 PM
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Re: Calculations???

There hasn't really been any improvement on the offerings in that area since ChoPs. Kelby put out a lower level book that might help you out, and I believe Katrin's masking book might delve into it a bit. I haven't had the ambition to do it.

Check out Margulis's books. Just keep an open mind and take what you need from them.

Chris
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Old 09-29-2008, 05:24 PM
vapour vapour is offline
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Re: Calculations???

Is ChoPs how you learned Chris or did you learn by trial and error?
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Old 09-29-2008, 08:24 PM
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Re: Calculations???

I thought the invention of layers made a lot of the Chops book obsolete.
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Old 09-29-2008, 11:34 PM
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Re: Calculations???

I do have the ChoPs book, but I only got it because I admired Bert Monroy's work very much and wanted his autograph. That was a LONG time ago. When he signed I told him I was going to be doing a book on calculations also. He just had this look in his eyes. I should have noticed it more and strayed away altogether.

I am self taught with the use of Calculations and Apply image. I actually learned Apply first and then discovered Calculations by accident. Back then it had another blend mode that was magic for compositing.

And still learning. I have not done it in years except for advise to Katrin but am now starting to dive into it for a second dvd.

Chris
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Old 09-30-2008, 06:07 AM
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Markzebra Markzebra is offline
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Re: Calculations???

Still got a lot to learn about that area. Seem to remember the CHoPs book floating around in a studio I once worked, and dipping into it, should have borrowed it I guess. Apart from masking what I do use calculations for is to create a good Luminosity channel, where digital noise is a factor, and its been extremely successful.

Its probably true to say that layers have made these channel operations less necessary- by this I mean the use of layer blending where its possible to switch channels off and use opacity and blend modes, can accomplish much of the same thing. Knowing how to extract channels from this is of course still important.

I've been asking them for years to improve calculations and apply dialogs - at one point I asked for dynamic layer masks, where the mask or channel would update on the fly. I see now in CS4 they have now implemented this, beginning with Color Range (always my first tool for channel based selections anyway) - so its looking that in some future version the whole business of channel ops might become more "discoverable"
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Old 09-30-2008, 01:08 PM
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Re: Calculations???

Mark

Certainly a bunch can be done in layers and blend modes combined with turning channels off and blend if. It is almost the same but I still cannot combine two channels through a third to achieve what I might need to be done.
Fixing the digital noise is a cool way of using Calculations. Love to hear how you go about it.
Unfortunately, I don't think that the calculations or apply image are going to change anytime in the near future. Like you I have been asking for man, well over a decade to get these updated. I've put in a feature request on every build since version 3 and it has gotten nowhere. Not that I expect them to jump just because I asked. But a LOT more high profile people than I am have been asking since the mid-90's for an upgrade to no avail. They're not a consumer/prosumer tool and are rarely if ever tweaked. As a matter of fact I have to go report a bug with calculations when I am done viewing this board.

They did do a pretty good overhaul of Color Range and you get MUCH better masks with it.
It is not quite as dynamic as I think you might be thinking, but it is possible to change an existing layer mask with it. I'll dig up a quick tutorial on it that I posted on the Beta board and stick it up here when CS4 is released.

Mark, I know you are over the pond and all, but if you can't find the ChoPs book let me know. You can borrow mine. Although it really doesn't get into the stuff that I do with it. You might just as well do a search for kai's chops online, the book is VERY similar to what he wrote about so long ago.

Chris
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