PS Challenge- Remove Magenta Cast

Discussion in 'Digital Darkroom' started by ross_lipman, Jul 7, 2021.

  1. Nikon D7100 / 18-140mm @70mm / ASA 1600 / Camera Flash / Auto WB / f11 @1/60

    All pics taken have a magenta cast. Attached picture is representative of the batch.

    Please disregard the black box ;-)

    Thank you !

    Sample.jpg
     
  2. 1658948_a3f5086d3e2f1e2e026dbbe20294fc1f.jpg
    Touched the "remove color cast" dropper to the table cloth and then desaturated magenta just for good measure.
     
  3. This is where I would have eventually taken it, PSE8.
    1658948_a3f5086d3e2f1e2e026dbbe20294fc1f (1).jpg
     
  4. This image needed a little more life in it. So I added a face, cloned out the black square and converted all to B&W. 1658948_a3f.jpg
     
  5. Opened in Rawtherapee.

    Selected 'Auto' white balance

    1658948_a3f5086d3e2f1e2e026dbbe20294fc1f-1.jpg
     
  6. I played around with white balance based on the tablecloth but in truth I like the original image better. It more resembles what I suspect the original lighting looked like. That's the same reason I use the "preserve lighting" white balance in my Z6. Remember, almost any color error is acceptable as long as it's warm! There's a signifigant difference in color between the top of the, presumably white, table cloth and the side. The top might be "seeing" some of the back wall, or the front could be artificially bluish. None of it made me terribly happy so I removed, or at least altered, the color cast with the auto function in Luminar and jazzed it up with their AI filter. It's easy to get heavy handed, but I still like it better.

    m_cast_lum_sm.jpg
     
  7. I tried several approaches in Lightroom: 1. Manually modifying temp and tint on the basis of the histogram to get a feel for what I might aim for, 2. White balance on the tablecloth, 3. White balance on the shirt to the left, and 4. Auto white balance. I was pretty sure that using the tablecloth or shirt wouldn't work very well because "white" fabrics are often biased toward blue to make them appear whiter. Sure enough, everything started looking yellowish, but they both also gave a sizeable reduction in magenta (temp +2, tint -16). The Lightroom Auto setting took the magenta down by a similar amount, but also further shifted the temperature toward blue (temp -16, tint -21) and made it look too cool. I then manually increased the temp to -11, and I used a soft brush to increase the white point (+33) and reduce highlights (-18) on the main subject to compensate for the fact that he was farther from the flash than the shoulder on the left, and I darkened the lower left corner slightly. The result:

    1658948_a3f5086d3e2f1e2e026dbbe20294fc1f-3.jpg
     
  8. Errrm. The Emperor isn't wearing any clothes!

    I don't see any magenta cast in the first image posted to begin with. Only a slight red/yellow cast.

    Is your monitor calibrated? And your device colour-profile aware?
     
  9. Using PS CS6, I used Image > Adjustments > Color Balance. I moved the Magenta-Green slider to +30 and the Yellow-Blue to +14
    1658948_.jpg
     
  10. With RawTherapee, set the white balance from the napkin beneath the glass.
    1658948_a3f5086d3e2f1e2e026dbbe20294fc1f-6.jpg
     
  11. I got curious about how the different efforts compared to one another, so here they are, with similar ones grouped vertically. #1 is the original, and I think I got the numbers in the same order as in the thread:

    2-1658951_08941081f95bfaae878537e9c73b5434-Edit.jpg
     
    steve_gallimore|1 likes this.
  12. For what it's worth, I think that my 'effort' (3) - Rawtherapee 4.2 (so 2014) on auto, is far too cold, I actually prefer the original!
     
  13. processed image.jpg
    Here is another version using Affinity Photo rather than Photoshop for comparison. Auto levels, then auto colors, then auto white balance. Looks pretty good to me, but then I thought that the original looked pretty good.
     
  14. Just curves but the screen I am on now is off ;)
    magenta-1.jpg
     
  15. A thankless task IMO. Mixed lighting like this is a no-win situation.
    IMG_20210717_153204.jpg
    Curves used to attempt to get everything that might be white or grey to look neutral(ish). But the flesh tones have suffered as a consequence. The table cloth top is always going to have a red cast, and the tungsten-lit curtains are always going to be yellow.

    Still not seeing any obvious magenta in the original.
     

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