Recipe for BW with Channel Mixer.

Discussion in 'Digital Darkroom' started by patricklavoie, Oct 13, 2005.

  1. Hi this is not a question! Only infos for people who like working with channel mixer. Your
    comment are always a pleasure : ) have fun. Use them with channel mixer red-green-blue. In
    monochrome mode._Agfa 200X: 18,41,41 / Agfapan 25: 25,39,36 / Agfapan 100: 21,40,39 /
    Agfapan 400: 20,41,39 / Ilford Delta 100: 21,42,37 / Ilford Delta 400: 22,42,36 / Ilford Delta
    400 Pro & 3200: 31,36,33 / Ilford FP4: 28,41,31 / Ilford HP5: 23,37,40 / Ilford Pan F:
    33,36,31 / Ilford SFX: 36,31,33 / Ilford XP2 Super: 21,42,37 / Kodak Tmax 100: 24,37,39 /
    Kodak Tmax 400: 27,36,37 / Kodak Tri-X: 25,35,40 And these basic ones: Normal Contrast:
    43,33,30 /High Contrast: 40,34,60 and at last a generic BW: 24,68,8. I like to 50,50,0 or
    25,75,0.
     
  2. You forgot Kodak HIE! ( infrared ) 100,100,-100 . Remember to run the saturation up before converting to BW with the Channel Mixer!
     
  3. This is really good, I did not know about this!
    So, can you take a BW converted by RGB channels and then add these values to the channel mixer?

    Thanks
     
  4. This is really interesting! I've never seen such a comprehensive compilation. How did you arrive at these settings, Patrick?

    Gustavo, these are channel mixer settings to emulate various B&W emulsions with color images.
     
  5. HUGH_thanks for the info, i will add it. I did know about it. I do my IR in another way in 4-5
    step.
     
  6. GUSTAVO_No! You have to work with a Color RGB.
     
  7. EDWARD_I found many of these around the web, other was discover by trial and error, and as
    a professional photoretoucher i develop a good eye to mimic some process. They are
    probably not perfect but pretty close to reality.
     
  8. Can you put it for a newbie?
    Wistler
     
  9. In Photoshop, if you whant to do nice BW from a color picture in RGB mode, use channel
    mixer in monochrome mode, enter those value at the appropriate place. could not be more
    newbie than this : )
     
  10. Wonderful results on a few images I tried it on. Thank you!
     
  11. Patrick, thanks for the very useful information!
     
  12. Patrick, very nice indeed. I was experimented and it works very good.
    Now, is the same thing to emulate color?
    Like Velvia, etc?
    Rgds
     
  13. No i use channel mixer for BW only. For color try hue/sat, curve, level etc....
     
  14. Patrick,

    Re: The 4-5 step IR method mentioned in your Oct. 14th post.

    ****************************

    " HUGH_thanks for the info, i will add it. I did know about it. I do my IR in another way in 4-5 step."

    ****************************

    Would you take a moment to describe it?

    Thank you.

    Roger
     
  15. Do you have numbers for this film? Would they be similar to Ilford FP4? Thanks.
     
  16. SIMPLE BW IR FROM DIGITAL COLOR PICTURE 01_adjustment layer/ hue saturation/ -100 saturation 02_adjustment curve/ OK/ mode change to overlay 03_reselect your background 04_double background/gaussian blur like 15-20/ OK/ mode change to screen 05_reselect the last layer ( should be your adjustment curve ) 06_create layer/ fill w 50% gray/ mode softlight/ apply noise monochromatic, gaussian, to taste.... Voila! a look alike BW IR photo, without the complexity of using filter and gadget. have fun : )
    00EE29-26549484.jpg
     
  17. The original set of numbers must be relative to something. The RBG colors of the original photo are obviously also dependant on the film before scan, the scanner response, or if from a digital camera the response curve of its sensor. Generally these would be adjusted to produce a neutral gray image printed in color of a gray original and also reproduce a standard color chart as accurately as possible.
    This would be done by setting the RGB levels and could then be used to make an accurate color rendition.
    Then the Channel mixer in Photoshop (or Corel Paint Shop Pro) would be used to make the monochrome image emulating the responce curves of the various B&W films shot without filters.

    Do you agree with that statement? Or am I missing something.
    -------


    Obviously the IR blue channel negative number trick only makes the image similar to the effects seen on IR film without closely studying it. The real rendition of IR is out side the spectra of RGB and so would be somewhat different. That would be perfectly fine for an interesting image, which is what is usually desired when not shooting with an IR filter when using IR film. If the image is for a scientific study then this method is not going to do it as nothing in the final image will show what the scene really looked like in infra-red.
     

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