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Forums > Digital Art and Retouching > Editing with gamma 1.0 or 1.8 Search   Reply
Photographer
BlueMoonPics
Posts: 3,477
New York, New York, US


For editing files in Photoshop I save tif files with ProPhoto RGB colorspace.
In photoshop I use the working space of ProPhoto RGB which is normally set to a gamma of 1.8.

I've recently read that some people are using a linear gamma, i.e.: 1.0, as their working space.

Is there a difference or advantage to using a gamma of 1.0 as opposed to a gamma of 1.8 or even 2.2 when editing?
Mar 09 13 02:01 pm  Link  Quote 
Retoucher
Krunoslav Stifter
Posts: 3,843
Santa Cruz, California, US


BlueMoonPics wrote:
that some people are using a linear gamma, i.e.: 1.0, as their working space.

Where did you heard that? Possibly you misunderstood. Linear gamma 1.0 is used in any RAW file since that is the way camera captures images, but do several reasons and long complicated history of analog and digital imagery all images at some point get encoded to 1/22 gamma and decoded typically to gamma 2.2 or approximation of it. One of the exceptions being for mentioned ProPhotoRGB that indeed has gamma 1.8

BlueMoonPics wrote:
Is there a difference or advantage to using a gamma of 1.0 as opposed to a gamma of 1.8 or even 2.2 when editing?

No, there is no real advantages except few complicated exceptions that I can think of and in fact much of the digital history in regards to images and video has been spend to not work in Gamma 1.0. So going upstream at this point seems contra productive.

Mar 09 13 02:20 pm  Link  Quote 
Retoucher
Krunoslav Stifter
Posts: 3,843
Santa Cruz, California, US


This is partial video that I recorded on the story of Linear Capture and Gamma Encoding for my upcoming DVD. It just so happens that it specifically talks about the topic your brought up so I will share it here.

http://www.mediafire.com/download.php?985t675a4sps13d
Mar 09 13 02:25 pm  Link  Quote 
Photographer
Sean Baker Photo
Posts: 8,036
Silver Spring, Maryland, US


If you really care about the difference, I would start here:

http://www.ledet.com/margulis/ACT_posti … -gamma.htm

But you may want a cup of coffee / a stiff drink before starting smile.
Mar 09 13 03:14 pm  Link  Quote 
Retoucher
Pictus
Posts: 891
Teresópolis, Rio de Janeiro, Brazil


Gamma 1.0 offer advantages for some processes, that is why Lightroom works internally in gamma 1 http://ptgmedia.pearsoncmg.com/imprint_ … _Space.pdf
Downsampling can benefit by using gamma 1, look here http://www.4p8.com/eric.brasseur/gamma.html and http://www.modelmayhem.com/po.php?thread_id=812189

Some color spaces do not use gamma 1.8/2.2, they use L*
Here deep explanation about gamma http://www.marcelpatek.com/gamma.html
and here a thread about ECI-RGB http://www.modelmayhem.com/po.php?threa … 044&page=1 and http://forums.dpreview.com/forums/post/39571935
Mar 09 13 08:34 pm  Link  Quote 
Photographer
Artifice
Posts: 30,927
Los Angeles, California, US


Mar 09 13 08:47 pm  Link  Quote 
Retoucher
FLEXmanta
Posts: 1,001
Madrid, Madrid, Spain


I don't know the advantages of using a linear TRC for editing when most of the workflow has equidistant luminosity L*?

Your eyes are L* and the profile conection space CIExy is L* (used every time you convert from one profile to another such as from RGB to CMYK).

Set your monitor to L* and work in an L* color profile like eciRGBv2. That is possibly the best color workflow there is.
Mar 10 13 12:59 pm  Link  Quote 
Retoucher
Krunoslav Stifter
Posts: 3,843
Santa Cruz, California, US


FLEXmanta wrote:
Set your monitor to L* and work in an L* color profile like eciRGBv2. That is possibly the best color workflow there is.

If you are only using eciRGBv2 than it is, otherwise there is a downside to this. All other color profiles are not L* so Photoshop does the adjustment for you and you don't get a benefit from calibrating to L* In other scenarios where you view images in non color managed applications you can get images that don't always look good, especially compressed images for web. Only scenario where it makes sense to me is in the workflow you mentioned with pretty much exclusively eciRGBv2, but that is not for everyone. Only people who predominately use that workflow and use that monitor primely as a workstation and nothing else. Also not every monitor out there is convenient for that kind of calibration so it does depend on a lot of factors. Certainly one solution does not work for everyone.

Context is everything. For example you with your monitor and your workflow and your final  output makes perfect sense and I fully support your decision to use that workflow but not everyone is doing the same and I think that is important distinction to make.

Theoretically next to linear gamma, L* would be probably best standard for some ideal future if we could shift all our standards to that, but I don't see it happening anytime soon. So far eciRGBv2 seems to be the only step forward and I'm not even sure if it's officially accepted as standard yet. You follow that more than I do so I maybe I'm mistaken.

Problem with linear gamma is that it's hard to switch to new standards especially when we have so much hardware and software already prepared for non linear gamma. But problem of calibration for example would be much simple for simpler math if everything was liner but we would also need more data to represent the same image, todays and future software and hardware could handled that aspect pretty easy, but again standards of the past haunt us today sort of speak.

Mar 10 13 02:07 pm  Link  Quote 
Retoucher
FLEXmanta
Posts: 1,001
Madrid, Madrid, Spain


Krunoslav-Stifter wrote:

If you are only using eciRGBv2 than it is, otherwise there is a downside to this. All other color profiles are not L* so Photoshop does the adjustment for you and you don't get a benefit from calibrating to L* In other scenarios where you view images in non color managed applications you can get images that don't always look good, especially compressed images for web. Only scenario where it makes sense to me is in the workflow you mentioned with pretty much exclusively eciRGBv2, but that is not for everyone. Only people who predominately use that workflow and use that monitor primely as a workstation and nothing else. Also not every monitor out there is convenient for that kind of calibration so it does depend on a lot of factors. Certainly one solution does not work for everyone.

Context is everything. For example you with your monitor and your workflow and your final  output makes perfect sense and I fully support your decision to use that workflow but not everyone is doing the same and I think that is important distinction to make.

Theoretically next to linear gamma, L* would be probably best standard for some ideal future if we could shift all our standards to that, but I don't see it happening anytime soon. So far eciRGBv2 seems to be the only step forward and I'm not even sure if it's officially accepted as standard yet. You follow that more than I do so I maybe I'm mistaken.

Problem with linear gamma is that it's hard to switch to new standards especially when we have so much hardware and software already prepared for non linear gamma. But problem of calibration for example would be much simple for simpler math if everything was liner but we would also need more data to represent the same image, todays and future software and hardware could handled that aspect pretty easy, but again standards of the past haunt us today sort of speak.

Still, I believe, and I'm no expert, that if both the monitor and the PCS share the same tone response curve, then the less the color engine will have to modify the image in order to reproduce it correctly. The less translation, the better.

Image(L*)-->PCS(L*)-->screen(L*) is always shorter than the widely used but messy Image(sRGB_TRC)-->PCS(L*)-->screen(gamma2.2 or native)

Having said that,the L* calibration and usage of eciRGBv2 as working space combo mainly benefits people whose workflow is 99% of the times "from camera to magazine".

eciRGB was very recently defined as standard (finally).

http://www.iso.org/iso/home/store/catal … mber=54745

Mar 12 13 11:14 am  Link  Quote 
Photographer
Fima Kurnia
Posts: 64
Jakarta, Jakarta, Indonesia


Krunoslav-Stifter wrote:
This is partial video that I recorded on the story of Linear Capture and Gamma Encoding for my upcoming DVD. It just so happens that it specifically talks about the topic your brought up so I will share it here.

http://www.mediafire.com/download.php?985t675a4sps13d

Hi Kruno..
where you put the other video (: heheee

Mar 12 13 03:29 pm  Link  Quote 
Retoucher
Krunoslav Stifter
Posts: 3,843
Santa Cruz, California, US


Fima Kurnia wrote:
Hi Kruno..
where you put the other video (: heheee

Other video? What do you mean? Maybe I mentioned it somewhere.

Well, this video is just a part of color management section for my new DVD and it was not meant to be the only video but it can be watched as one so I posted it here, since it deals with the question OP asked.

The other videos will be available when the DVD is released. I cover a lot of ground. Color management being just one section and this video being even smaller part of that.

Mar 12 13 03:33 pm  Link  Quote 
Photographer
BlueMoonPics
Posts: 3,477
New York, New York, US


I want to thank everyone for their tremendous help and all the links about this complex subject.
And thank you so much for the video Krunoslav-Stifter!
Mar 22 13 12:45 pm  Link  Quote 
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