4 Replies Latest reply on Jun 8, 2014 11:36 AM by jdanek

    Color Gamut, Intent, profile conversion… bad result… what should be the workflow?

    IdamIndia Level 1

      This color management thing is driving me crazy! Really. If I start I may end up in a mashup of several things and spoil the focus for any title to of the post. So I will stick (try to atleast) to just what may be expected from the title I have given this post (hopefully it is apt!)


      Ok. So first, I am having a hard time getting my slide scans to behave, that is, look in digital as good as they look on the wall when projected! It is white wall, in case one wonders my color management expectations are shifted due to a blue wall. Scans are dark, very dark. Specs: My monitor is calibrated (so they look even more dark). I have to use gamma 2.2 in silverfast to get them to show details in the shadows. Specs: I am using HDR scans which are supposed to be darker due to multiple exposure/scans.


      Once out of Silverfast HDR, I get them into Photoshop.

      Specs: Photoshop CS6. Image specs: RGB 16bit color. Embedded profile used. Here are the color settings from Silverfast and Photoshop (see images below)


      Silver Fast Settings related to Color and CMS, I have moved to the end of post.


      Let me explain the issue first:

      1. Color image has issues:

      - bad magenta colors in sky

      - Highlights have some sort of ornage/peach which looks odd

      2. Controlling color by various methods results in one or the other problem

      - one part is fine, the rest is screwed

      - gamut warning goes away from say the cloud edges, it moves to the middle or vice versa


      But this is good illustration of what I came to know, color gamuts not visible on monitors are generally the "blues" and "greens". I guess these saturated color regions are the ones giving gamut warnings.


      Assumed Workflow:

      1. Get the image in Pshop

      2. Play with it to get desired result

      3. Convert to profile and format for printer (cmyk magazine print)


      2 is just not under control due to color not behaving consistently. That magenta just does not become neutral in the sky!

      3 Now, when I convert to say CMYK or RGB (have tried both), I still have that awful magenta and the bad highlights over rocks and the field. I believe the iamge has more data, but with the intent, wont the conversion bring those awful looking colors to something closer to expectations? (magenta should become a bluish or greyish color)? Instead they remain just the same!



      What should be the workflow to get a high gamut image to a lower gamut image, preserving whatever we can?

      My assumption to this simple workflow seemed to be wrong. Please help. Also, it may be due to the significantly large 2.2 gamma setting of Silverfast that I am forced to use to get details in shadows (?). That is what I share all settings in my workflow.


      Here is the image in question: Notice the deep blue are on the left sky, the bright cloud, the rock highlights and the fields and house below.


      Image Issues _0000s_0001_normal image.jpg

      With Gamut warnings

      Image Issues _0000s_0000_gamut warning.jpg





      Scanner Silver Fast Setting:


      SF settings 1.pngSF settings 2.png


      Photoshop Color Settings, and Color Soft Proofing setting in Photoshop:

      PShop Color settings.pngImage Issues SoftProof Settings.png

        • 1. Re: Color Gamut, Intent, profile conversion… bad result… what should be the workflow?
          SasquatchPatch Level 2

          It looks like you're using Gamma 1.0 for your SF HDR gamma. That will make a very dark scan. You're also not embedding your profile from SF, at least that what it looks like according to your preferences.


          You really want to scan in RGB and preferably 16 bit per channel RGB. If you can set accurate highlight and shadow points in SilverFast, that will go a long way to getting the right, or at least much closer, color. I would set an output gamma of 2.2 and use Adobe RGB as your output profile. When you open your scan in Photoshop, set the dropdown window on the lower left corner of the file to read Document Profile. It's a nice reminder to see what color space your file is in.


          From there, you need to go through the standard color/tonal correction steps you'd use for any image - set highlight and shadow points using Curves adjustment layers. Finding and setting a neutral highlight and shadow will take care of about ninety percent of your color problems. If you still have issues like magenta skies, you might need to use Hue/Saturation or Selective Color to address those. You might want a touch of highlight/shadow to control contrast. You might need a bit of sharpening, preferably selectively. Every image is unique.


          You want to have your RGB file looking fantastic on your hardware calibrated screen before your even thing about CMYK. After you do that and convert to CMYK, then check your black and white points again for proper ink values. Y'know - a white with a bit of detail at something like 4c, 2m, 2y, 0k and a white with tone but no detail at 1c,1m,1y.  From there, especially for magazines, you might check saturated colors for contamination and use Selective Color to make final tweaks to colors and even to the blacks as well.

          • 2. Re: Color Gamut, Intent, profile conversion… bad result… what should be the workflow?
            jdanek Level 4

            What scanner are you using?  Flat bed or drum?  The only thing that will deliver decent shadow detail is a 4.0 d-max ( few scanners can achieve that ).  Has your scanner been calibrated?  If so, you'd use the scanner profile when scanning similar media ( slides ).  In Photoshop, try a Rendering Intent = Perceptual.  It's pointless to show us pictures of your files because we cannot see the original(s).  There are a few things you can do to bring out the color you are looking for.  I'd recommend you get a copy of "Photoshop LAB Color" and "Professional Photoshop Photoshop" by Dan Margulis.  Also, what do you have in place for proofing?  You refer to screen views, but are you seeing casts in your proofs?

            • 3. Re: Color Gamut, Intent, profile conversion… bad result… what should be the workflow?

              You are trying to do something that is very, very hard to do.  Getting a high quality scan of your slides requires that you get not just the color, but also the dynamic range, contrast and saturation correct.  The issue with the cloud is a contrast problem, and there appears to be a color problem as well.  Here's what I suggest:

              • Project the slide on the wall, and adjust the same image on your computer while observing the image on the wall. 
              • Turn off HDR, it's not for this.  Play with shadow / highlights instead.
              • Use sRBG across the board.
              • Set your scanner for "Perceptual Intent"
              • The "Optic film"  color profile should be "Default"

              When you look at the image on the wall, your eyes take a 500MB image with a million to one dynamic range.  The monitor on your computer can only display a dynamic range of 64,000 to 1, and the scanned image is only about 3MB, so you're not going to get it to look as crisp as what you see on the wall.  But, there are tricks to get it close!  Play with the sharpness and contrast.  Your eyes are 50 times more sensitive to contrast than color, so just get color close, and spend your time on contrast. 

              Good Luck!



              • 4. Re: Color Gamut, Intent, profile conversion… bad result… what should be the workflow?
                jdanek Level 4

                I took your first screen shot image and saved it as "MountainTop1.tiff", ince it did not have an embedded profile, I applied Adobe.RGB to it.  I then saved a copy and named that "MountainTop2.tiff".  In the copy I converted the image to LAB.  The following screen shots show the curve adjustments and theri results in the copied image, which set next to the original is drastically different.  I have no image to compare it to and the screens just show what is possible...


                Screen shot 2014-06-08 at 06-08-14 ◊ 2.19.38 PM.png


                Screen shot 2014-06-08 at 06-08-14 ◊ 2.19.21 PM.png

                Screen shot 2014-06-08 at 06-08-14 ◊ 2.19.03 PM.png

                Screen shot 2014-06-08 at 06-08-14 ◊ 2.20.14 PM.png


                My next step would be to save a copy of the LAB image to RGB via Adobe RGB profile and then save a copy of that image as CMYK using the SWOP web coated v2 profile.  Only I have no idea what the original slide looks like projected, therefore the above screens only show what is possible.  The above are all 8-bit RGB images.