Using Photoshop to create greyscale images from full colour ones just got even better using the new channel mixer in CS3.
There are several way to do this, and the channel mixer has always offered the most control. Now in CS3, it offers some very interesting pre-sets as well. All based around traditional b&w film & coloured filters. This image shows the dialog box accessed by the menu-bar, image>adjustments>channel mixer.
The presets drop-down menu at the top allows you to choose between several predetermined spectral responses and creating your own custom set of values.
- Blue Filter
- Red Filter
- Orange Filter
- Green Filter
- Yellow Filter
Use of these kinds of filters have had a long history in b&w, photography. Panchromatic film in itself has only been a reality in photography since the 70's. Prior to this b&w film was more Orthochromatic ie sensitive to the blue and green but not the red end of the spectrum, this is why so many photographs from the early history of photography had washed out skies, and also saw many many smart photographers take 2 exposures, one for the foreground and one for the sky, from the same camera position, then in the darkroom simply sandwiching the 2 negatives together to produce a print. Others simply, kept a collection of skies on hand in the darkroom and used as needed.
Now CS3 enables you to mimic the effects that these filters have in how colours are represented in a black and white print. Yellow for example it is said most closely mimics the world the way we see it and of course Red filters produce dramatic skies, while colours like green and blue can be used quite effectively in the right situation.
When working traditionally the colour of the filter you used with block it's opposites and passed more of it's own colour. So for example when using a Red filter less Green and blue light strikes the film than red. Red objects reflect more red light creating a denser negative, producing a lighter print. Where as less blue and green light strikes the film making for a less dense neg and a darker print.
I can only wonder now at the demise of silver gelatin printing. As anyone, armed today with a modern DSLR, and a good A3 ink-jet printer can easily produce some wonderful prints using these technologies.
the real question is though is there a measurable qualitative difference between the two output methods, personally I still see differences in Silver Gelatin prints over ink-jet ones, but after 20 plus years of working with the medium I've come to appreciate some unique and subtle qualities that I've yet to see in ink-jet prints.
I may, in an upcoming article, show the differences between the pre-sets at least.Another approach on Luminous Landscape