Grayscale images and retouching in gamma 1.8-2.2

[Tech]

Per subject title, anyone out there does their retouching in gamma or dot gain? Pros and cons? Aside from the obvious gamma is screen profile and varies from monitor to monitor?

 

[michaelejahn]

Hi Tech,

If what you are asking is "hey, when I go to open up a darker area to see if I can get more detail" - and you are wondering what you should be using in your Adobe Photoshop settings - I guess I would suggest that what you need to do is come up with a way to simulate how this will print on screen - this normally requires some color management approach - since the dynamic range of print is much flatter than what is capable on your screen, most retouchers would probably suggest 1.8 as a 'generalized' statement here, but that really is not all that needs to be considered - each monitor has its own response rate - even from the same manufacturer - in highly color calibrated work environments, such as is used at JC Penney - where everyone has EIZO monitors - well, I have heard that they run the monitors at 1.8 to preserve - that is, when you run them at 2.2, the color fades faster.

Hope this helps !

 

[meddington]

I generally do retouching on grayscales using a grayscale profile rendered from the appropriate CMYK profile (choosing "Load Gray" and selecting Gracol2006_Coated1.icc for example, which generates a "Black Ink" profile as the gray working space). I would also generally convert incoming grayscale images to a custom black ink profile either before or after retouching, but never assigning a profile to take the original tagged profiles place (unless this achieves a desired visual result).

 

[Lukas Engqvist]

I know it is a little of topic but. I also prefer to work with K from CMYK profile.
If you are using non destructive editing as far as possible I think that is most important.
Keep the destructive math to a minimum.

 

[Tech]

Hmm, perhaps I'm asking the wrong question here. Let me try rephrasing it...

I ran a simple test on a grayscale image that was corrected in gamma 1.8 vs dot gain 10%. I then took gamma 1.8 image and convert it to dot gain 10%...naturally on screen, it looks identical to image that was corrected in dot gain 10%. Likely wise, convert the gamma 1.8 to dot gain 20% vs dot gain 10% to 20% looks identical. No surprises here.

The real questions is which method reproduces most accurate tonal range on press? Why do some people insist on retouching grayscale images in gamma? Am I missing something here?

 

[meddington]

The real questions is which method reproduces most accurate tonal range on press? Why do some people insist on retouching grayscale images in gamma? Am I missing something here?

Other than legacy practices and learned behavior, I don't really see a compelling reason to use gamma over dotgain for editing. I would say that the most accurate tonal response would come from the black printer of the intended output condition...derived from the appropriate cmyk profile.

 

[benr]

I think your question breaks into two parts: retouching, and accurate output. I personally treat it just as I do when retouching in RGB for a CMYK final.

Since Gamma 2.2, or Dot Gain 20%, etc. are just idealised working spaces, the choice has more to do with the performance of that space for your work than anything else. I personally use Gamma 2.2 and 16bit* for all my grayscale work. Although you could get the same result with a different curve in another space, I find that when curving in the Gamma 2.2 space I use more "organic" curve shapes to better effect (the distribution/re-distribution of tones along the scale obviously varies in different spaces).

Ultimately, after flattening, I convert to 8bit and to a CMYK "rich black" or black only profile based on the output condition. I'll generally do perceptual conversions for grayscale work.

If you're aiming to retouch directly in the best choice of output space, the answers would be different.


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* I use 8bit for colour, since I've proven to myself that there's rarely an advantage to 16bit with multiple-channel images, but for single channel images like grayscales, 256 steps isn't enough.

 

[Lukas Engqvist]

I don't convert to rich black, use a seperate profile if I convert to CMYK so that it still is High - Max GCR.
Normally I colour grey in InDesign with a special swatch at 20 15 15 100 (or something there about, depending on if I want a cool or warm or neutral feel)