Cotty <[EMAIL PROTECTED]> wrote: >On 31/10/05, [EMAIL PROTECTED], discombobulated, unleashed: > >>Thanks to all who commented. By the way, this BW conversion was done the >>fast and easy way: A simple mode change to grayscale followed by >>adjustment of the tonal range in curves. In that this simple procedure >>allows complete control of tonal range and that any more elaborate method >>takes you to the same place -- grayscale -- I fail to see the need for >>elaborate "recipes." I mentioned some of these elaborate procedures to a >>professional photo retoucher a couple of weeks ago. She simply said, >>"That's all a lot of bullshit for people with too much time on their >>hands." That being said, I sometimes use the channel mixer because it's >>fun. But I don't think it's necessary. > >That's very interesting you say that. I have often suspected it.
But it ain't true. This "professional photo retoucher" doesn't know what she's talking about. There are some tonal changes that can *only* be accomplished before the image is converted to grayscale. That's why those of us who use B&W film often use color filters when shooting. A trivially simple example: You can paint an object in 3 shades of gray, red and green each of which will translate to exactly the same shade of gray with a particular B&W film or greyscale conversion. Once the image is in greyscale, you can play with the levels and curves controls until the heat death of the universe without them ever changing in relation to each other, but using a color filter when shooting B&W film, *or* adjusting color balance in Photoshop before converting a color image to greyscale, will give you control of their relative density. This applies to all colors to some extent, and control over these characteristics are what the channel mixer procedures and other recipes accomplish. What you're dealing with isn't "bullshit for people with too much time on their hands" but rather "bullshit from a photo retoucher attempting to conceal a lack of understanding of some very basic photographic concepts". BTW: You can't use digital color balance changes to *exactly* duplicate the effects of a physical color filter applied during shooting, but you can get pretty close (and that's an entirely different discussion.) -- Mark Roberts Photography and writing www.robertstech.com
