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Shlomit Heymann
Shlomit Heymann
Inspiring
August 11, 2019
Answered

Old photo restoration - Bridge or Photoshop, RGB or Grayscale?

  • August 11, 2019
  • 4 replies
  • 1648 views

Hi guys,

I Have an old photo and I scanned it in 200% and 600 ppi, saved as Tiff.

Got a few questions I always wondered about:

1. I was wondering, if I want it to be Black/White, where is it best to do. Bridge or Photoshop?

2. Is it better first to change it to Black/White and then retouching, or the opposite?

3. What is best: Black/white Grayscale or RGB? Or shall I first do the Gray scale and than back to RGB?

Thank you very much

Shlomit

    This topic has been closed for replies.
    Correct answer D Fosse

    Without seeing an example it's impossible to give specific advice. But generally you will have more flexibility working in RGB. Don't throw away information before you have to.

    I'd also avoid grayscale as an output from Photoshop for other reasons. Grayscale is subject to standard color management, and it makes a huge difference what grayscale profile is used. This is all correctly handled inside Photoshop - but grayscale support outside Photoshop is mostly non-existent, and the final result therefore totally unpredictable.

    Grayscale data very often don't have an embedded icc profile to determine the tone response curve. Inside Photoshop that means the working gray gets assigned. The Photoshop default working gray is a dot gain profile with little practical relevance. You're much safer changing your working gray to Gray Gamma 2.2, which roughly corresponds to Adobe RGB, or sGray, which corresponds to sRGB.

    The problem is that other applications mostly don't know what to do with Gray Gamma 2.2, or sGray. So that profile usually gets thrown out, and the data just treated randomly. An RGB file with sRGB or Adobe RGB embedded has a much higher chance of being correctly treated.

    4 replies

    Shlomit Heymann
    Shlomit HeymannAuthor
    Inspiring
    August 12, 2019

    Dear All,

    Thank you so much for your advices. Here is the photo I want to work on.

    Although I'm not familiar with all the deep Photoshop options, I get help from tutorials and all your advices will help me on that.

    I wish you all a very good day...

    Shlomit

    rob day
    Community Expert
    rob dayCommunity Expert
    Community Expert
    August 12, 2019

    Here is the photo I want to work on.

    You haven't mentioned what the intended output will be—composite color printer or offset printing? Your scan obviously has color in it, are you trying to convert the original scan color so that the output is perfectly neutral, or are you trying to reproduce the original color? If the output is offset and you are looking for neutrality, RGB mode will convert to 4-color CMYK, while Grayscale mode will output to the black plate with no CMY.

    D Fosse
    Community Expert
    D FosseCommunity Expert
    Community Expert
    August 12, 2019

    https://forums.adobe.com/people/rob+day  wrote

    Grayscale mode will output to the black plate with no CMY.

    Yes, and that's a perfect example of the problems you can get with grayscale. You get the CMYK profile's black ink assigned to the data - but that's not the profile used when creating the file. So the tone response curve comes out all wrong.

    Unless you're prepared for that, and set your working gray up accordingly, so that you can assign that to the file and work with that:

    Derek Cross
    Community Expert
    Derek CrossCommunity Expert
    Community Expert
    August 11, 2019

    Save it as a PSD (and what the others state).

    Norman Sanders
    Norman Sanders
    Legend
    August 11, 2019

    You don't mention whether the photograph is a color print or vintage black & white, or sepia image. Assuming it is a color photograph, Photoshop's Mode > Grayscale is not recommended.

    To quote from Dan Margulis'* "Professional Photoshop", when referring to Mode > Grayscale "... no matter what color space the file is currently in, Photoshop creates an idealized version of it, and from that a weighted average to make a single channel. The formula is 3-6-1, three parts red, six parts green , one part blue." Margulis goes on to demonstrate why this formula "doesn't work."

    Depending upon the actual image, adjacent colors and their intensity, you may find that Image > Adjustments > Black & White presents useful starting options. In addition, if the image displays scratches, dust specks, lack of image sharpness and other distractions, there are several tools available to deal with them. If you run into a problem, post the image and ask for help.

    *Margulis is more widely known for his groundbreaking books related to Lab Color.

      Chuck Uebele
      Community Expert
      Chuck UebeleCommunity Expert
      Community Expert
      August 11, 2019

      As mention above rgb is best even for grayscale. You can often enhance a particular channel in rgb to give better contrast and detail, even if you want a grayscale image.

      D Fosse
      Community Expert
      D FosseCommunity ExpertCorrect answer
      Community Expert
      August 11, 2019

      Without seeing an example it's impossible to give specific advice. But generally you will have more flexibility working in RGB. Don't throw away information before you have to.

      I'd also avoid grayscale as an output from Photoshop for other reasons. Grayscale is subject to standard color management, and it makes a huge difference what grayscale profile is used. This is all correctly handled inside Photoshop - but grayscale support outside Photoshop is mostly non-existent, and the final result therefore totally unpredictable.

      Grayscale data very often don't have an embedded icc profile to determine the tone response curve. Inside Photoshop that means the working gray gets assigned. The Photoshop default working gray is a dot gain profile with little practical relevance. You're much safer changing your working gray to Gray Gamma 2.2, which roughly corresponds to Adobe RGB, or sGray, which corresponds to sRGB.

      The problem is that other applications mostly don't know what to do with Gray Gamma 2.2, or sGray. So that profile usually gets thrown out, and the data just treated randomly. An RGB file with sRGB or Adobe RGB embedded has a much higher chance of being correctly treated.

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