Simulating an orange filter in Photoshop

Discussion in 'UK Photography' started by Al Treacher, Aug 22, 2003.

  1. Al Treacher

    Tony Spadaro Guest

    Tony Spadaro, Aug 30, 2003
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  2. You're wrong again. I graduated with a PhD a few months ago.

    But it fits right into your pattern of writing as if you knew what you
    were talking about, when in fact you're wrong but can't be bothered
    looking up the facts.

    Interesting question: have you *ever* admitted you were wrong, about

    Dave Martindale, Aug 30, 2003
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  3. No, you're basically right. Their eyes automatically white balanced
    for the lighting available, while film is designed for a specific type
    of lighting. Exposing the film using different lighting messes up the
    colour balance of the negative. If you make a "straight" print from
    the film, it will show a colour cast.

    On the other hand, the lab *could* have corrected the colour cast, so
    that truly white objects were printed as white. So the prints didn't
    have to be green.

    Still, even if the prints were adjusted to get the whites correct, other
    things in the image may still be the wrong colour.

    Dave Martindale, Aug 30, 2003
  4. You couldn't see a "colour chord", because the range of frequencies that
    our eyes can see doesn't even cover a 2:1 range, less than an octave.
    There is no colour for which you can see the colour plus its second
    harmonic, let alone higher harmonics. We see roughly 400-700 nm
    wavelengths, and no more. While our ears cover something like 9 octaves
    (when young).

    Dave Martindale, Aug 30, 2003
  5. Al Treacher

    Martin Brown Guest

    It's a bit more subtle than that. The film response to the relatively
    strong green mercury line is out of proportion to how the human eye sees
    it. And the red emission from fluoro phosphors doesn't record very well
    on film. Couple that with the way the eye is very good at compensating
    for white balance of ambient light, whereas film records what was
    actually there (or at least what it detected as being there).

    Look at the emission of a fluorescent lamp reflected from a CD and you
    will see clearly how unlike natural sunlight or any other colour
    temperature black body it is. Its a matter of luck exactly how colour
    film responds to light containing bright spectral line emissions.

    Auto white balance on digicams can perform somewhat better, but with
    conventional film it is usually better to use filters to match the film
    to the light source. Digital post processing can be used to tweak things
    into shape for most of the common mismatched lighting and film

    Martin Brown, Aug 30, 2003
  6. That's a neat trick. Why didn't I think of something so obvious? Of
    course it's a diffraction grating - the AOL spectroscope. :)

    Roderick Stewart, Aug 30, 2003
  7. A good point. We can see plenty of colour discords though. :) It's
    difficult to imagine how music would work, or if it would work at all, if
    sound was like this.

    Roderick Stewart, Aug 30, 2003
  8. (Dave Martindale) wrote in

    See Dave .. he goes on and insults. He is playing games or worse.
    Good question - it would be interesting to see Tony's reaction
    to this question. Either - he don't see it - or - he is now
    immobilised for the next week or so.

    Roland Karlsson, Aug 30, 2003
  9. Al Treacher

    Tony Spadaro Guest

    Piled Higher and deeper?
    You haven't yet learned the most essential part of a good education:
    Education STARTS after schooling ends.
    Go forth and open your mind. Is modern education so bad that they give
    away degrees without ever teaching anyone to think? That's a rhetorical
    question - I don't expect you to be able to answer it, and don't worry - it
    isn't on the final.

    home of The Camera-ist's Manifesto
    The Improved Links Pages are at
    New email - Contact on the Menyou page.
    Tony Spadaro, Aug 30, 2003
  10. Al Treacher

    Tony Spadaro Guest

    Tony Spadaro, Aug 30, 2003
  11. Tony, you're laughable. I have been learning all my life, and much of
    it has been outside the classroom. But I'm not surprised you'd say this
    - you have a habit of just throwing out statements without worrying
    about whether they're true, and without even the slightest attempt to
    verify whether they're true.

    I see you're not going to admit that you were completely wrong in your
    previous attempts to attack me personally, either.
    Tony, you're the one who is refusing to think. There are at least three
    people in this thread pointing out that you're wrong: that the effect of
    an orange filter cannot be duplicated in Photoshop. There are one or
    two other people who, after reading the thread, have said that they
    now see that this is true, and that they learned something new. You're
    the only one who refuses to learn. I'd have to say you're the dunce of
    the class.

    Dave Martindale, Aug 30, 2003
  12. Al Treacher

    Joe Guest


    Will you all go and find an Orange planet.
    Joe, Aug 30, 2003
  13. Al Treacher

    Tony Spadaro Guest

    Tony Spadaro, Aug 30, 2003
  14. Al Treacher

    Bryan Olson Guest

    Try a Google advanced group search for group
    and author "Dave Martindale". No disrespect to other fine
    contributors, but I have Martindale topping my "always read"
    list for the group. He puts out an amazing number of
    consistently astute, clear, and helpful posts.

    Here, check it out:

    < Martindale&lr=&num=100>
    Bryan Olson, Aug 30, 2003
  15. Al Treacher

    Bruce Murphy Guest

    Newsflash. Tony has killfiled him out of deep-seated jealousy. Film at

    Bruce Murphy, Aug 31, 2003
  16. Don't your news reader have any threading?

    If it does - what possesses you to read the stuff in this thread?

    Roland Karlsson, Sep 1, 2003
  17. I've owned and used Photoshop since version 2.5 on the Mac. I know how
    to do colour correction with it.

    Now, a question for you: Do you know what an orange filter does? Do you
    know what a "metamer" is? Can you explain the effect of an orange
    filter on metameric colours? All the necessary information has already
    been presented in this thread.

    Dave Martindale, Sep 1, 2003
  18. Al Treacher

    Juno Guest

    Dave - when he doesn't (-: will you explain please.
    Give him a few days though to look it up and post a load of garbage.

    Juno, Sep 1, 2003
  19. Al Treacher

    Tony Spadaro Guest

    Yes I know both.
    An orange filter darkens light of every colour save orange or white.
    A metamer -- as I remember it is a pair of colours (possibly more) which
    are different but appear to be the same.
    An idiot is someone who thinks tossing around a few words and claiming to
    have advanced degrees will win him an argument no matter how assinine his
    argument may be.

    home of The Camera-ist's Manifesto
    The Improved Links Pages are at
    New email - Contact on the Menyou page.
    Tony Spadaro, Sep 2, 2003
  20. Al Treacher

    Bruce Murphy Guest

    A pretty terrible appreciation of colour theory there.
    Quick recovery by using a dictionary, pity that you can't grasp the
    implication of this definition though. Cutting and pasting obviously
    isn't the same as learning.
    Well you're clearly not that sort of idiot, noone has ever claimed
    that you had any sort of education.

    Bruce Murphy, Sep 2, 2003
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