Black and White photographers will often place colored filters in front of their lens in order to accentuate contrast in the final image. For example, placing a red filter in front makes the blue sky dark and dramatic while smoothing out people's skin. Green could have the opposite effect. These filters come in varying colors and intensities.

a good way to simulate these filters and have a bunch of control over the effect is to approach it this way: Create a Hue/Saturation layer effect above your image layer. Don't adjust anything at first, just hit OK. Change the Layer mode of that adjustment layer to "Color". Create another Hue/Saturation on top and reduce your saturation to zero and hit OK. Now open up the First Hue/Saturation you created and begin playing w/ the Hue slider - you'll see varying amounts of contrast as you move thru the spectrum of color. This can lead to far more dramatic B&W photos...

-JF

JF' is right to point out the issue of black and white film photography and the use of coloured filters. However, then going on to talk about the twin Hue/Saturation method (aka Film/Filter or Russell Brown) is sllghtly off target. There is nothing wrong with the method, it uses the channel information (dump any b&w conversion method that doesn't), and one can produce excellent results that way - incidentally there's a similar method available via the Adobe Camera Raw dialog.

However, the real equivalent of coloured filters (I've a load of experience of them) is the good old Channel Mixer adjustment layer. The end results are no different to those of that Hue/Sat method - but you are working much more naturally in tune with the film photographer's use of coloured lens filters. Red channel is like a red filter, makes blues darker in b&w, lightens reds, reduces haze, softens skin. Blue channel makes reds darker, lightens blue skies, etc. Working with the Channel Mixer is the same as lens filters and is a whole lot more natural than dragging the slider along in the Hue/Sat dialog.

It's also important to use digital's advantage of multiple conversions, like having endlessly graduated lens filters in your camera bag. Don't be afraid to use one masked channel mixer adjustment layer on someone's face, and another on the background etc. This can greatly vary the amount of tonal information that is rendered in the black and white version, and extends your ability to interpret the picture through the conversion process. For example, a red filter will make a suntanned man look pale-skinned in black and white, while blue emphasizes his skin - it depends what story you want the picture to tell. So think of it as two steps - the richness of tonal information carried over into b&w, and the balance between the tones which allows for your interpretation of the image for the viewer.

Anyway, whichever method you like, just remember that any method that doesn't allow manipulation of the channel values is second rate compared with these two.

The technique I normally use is to copy each RGB channel into its own layer, with the cleanest looking (usually red) channel on the bottom. The other two channels can then be mixed, painted out, or whatever. The blue channel is usually the worst when it comes to portraits, so many times it gets removed completely.

Experimenting with other color modes -- LAB for instance, can also be helpful.

The Lab produces a neutral rendition. That may be what you want, but that's all it does, chuck away the colour.

The Lab method produces a neutral rendition. That may be what you want, but all it does is chuck away the colour. It allows no selection-based conversion and is also irreversible after the file is saved and closed.

Many people don't think to use this technique as the name does not sound like it would work. Calculations found under the Image menu is a great alternative. It takes some playing around to find the perfect setting for each image but the results are a noise free black and white with a more accurate representation of an actual black and white image.

My typical settings to start with are something like this.
Source 1: Channel = Red
Source 2: Channel = Green
Blending: Multiply = 50%

The reason being, the red channel contains your contrast and tonal range, the green your detail, and the blue... well it's mostly junk like noise. In a black and white print, I typically want the most contrast, and detail and no noise, unless I add it later :)

It may not be easier but would likely produce a better print.

mark

You're right most people don't think of it. No preview, no selections, only 2 channels, irreversible after you close the file. Use calculations for masking, not b&w conversion.

John

calculations either saves as a new channel, or into a new doccument.

2 Channels??? Incorrect, you have all your channels plus alpha channels and you can also add mask channels for additional enhancements.

No Preview??? Incorrect again, It previews your entire image, not just a segment or a crop. Granted you need to ensure the little box labeled Preview is checked but it that way with most filters or effects. But I shouldn't have to tell you that.

Im not here to rebuke your technique, but I will argue with you if you give people false information.

*Climbs down from soapbox*

Yes, I have tried it and was posting from memory. Sorry, I was wrong about previews, but your b&w conversion cannot be adjusted afterwards (you need to redo it) and calculations does use the colour information from up to 2 channels. Sure, you can you use masks to make new documents to composite a selective conversion, though it's a contorted and ineffcient process that dates from the time long before adjustment layers and IMO is really best avoided.

not about to have a battle of wits with an unarmed individual...

Huh?

This post inspired me to write about some of these same issues at MacMove, a Mac website I write for. While the audience there is not as technical or experienced readers here are, some of you might find it interesting.

The article is here.

Believe it or not, I prefer using the Filtered B&W option in the free Picasa software. Too bad there is no version for the Mac.

hey folks,
I studied the old B&W film colour rendition characteristics and maybe somebody can use these setups to simulate 19th and early 20th century photographic materials.

first create a Channel Mixer Adjustment layer over your RGB image and
check the "Monochrome" checkbox.

and the settings are:
Colour Blind (only blue sensitive) film
R: 0
G: +20
B: +100
C: -12

Orthochromatic (B+G sensitive) film
R: 0
G: +44
B: +62
C: -2

Panchromatic (colour sensitive) film
R: +44
G: +38
B: +28
C: -6

it might be not perfect, but I think, usable.

Daniel

http://www.photography.hu