the black and white mixer is one of the most powerful features of Lightroom and has been around since the first version (in fact, you could say it has been around much longer, as the channel mixer adjustment layer in Photoshop).
One way to use them is to go in and feel your way around what looks best by moving the sliders or even by clicking that little round round target in the left corner of the mixer panel and then point on a color in your image and drag the mouse up or down, holding the left mouse key pressed down, which will lighten or darken this specific color range. A very powerful feature to quickly create those dark skies with bright white clouds that we know from Ansel Adams‘ timeless images (truth be told, he did much more than just use a red filter, but that’s a good starting point for this look).
The downside of this method is that you sometimes end up with ugly banding or very high edge contrast when two adjacent colors are set to very different filter levels.
As an alternative starting Point for, I have created a rather large set of parametric filters that allow me to get close to the desired look while maintaining a smooth filter curve to avoid the problems described above. I’ve used different mathematical functions to create these filter curves and parametrized them to get different contrast levels and color responses.
To give you an idea of the filter sets, here’s an exaple:
First, the original image
This image of two German Shepards was shot two years ago on a sunny fall day with the sun just above the frame. I like the picture in it’s color rendition, but I’ll use it as an example for the filter set here.
This b/w image has been created using the 1-blue-1-80 filter, which is a sinusoid filter with a relatively narrow bandwidth in both the positive (accentuated) and negative (darkened) colors. In this case, blue is given an 80% lightness push while it’s opposite colour, orange, is pulled to -80%, making the hedge appear almost black and thus almost blending the other, black dog into the background.
The second b/w image uses the 1-Blue-2-80 filter, again a filter with an 80% „amplitude“ but this time, it has a much broader positive shoulder and a rather narrow negative „trench“, meaning it will lighten a wider palette of colors and darken only a few. As the yellows and oranges are much less darkened by this filter than by the 1-Blue-1-80, the hedge comes out much lighter and the other dog is clearly visible.
As a landscape / sky example, this is a shot I took a few years ago on my journey to New Zealand. The original has very strong colors, helped by the fact that NZ is a country of colors and by some application of polarizer.
Without much tweaking, the 1-Orange-2-80 filter turns the sky dark, accentuates the white clouds and the light on the rocks in the foreground. The 80% setting might be a bit stark, but it helps to show the effect in this case.
The 1-Aqua-1-80 Filter yields quite the opposite Effect, the rocks are slightly darkenedand the sky loses almost all structure, turning into a featureless grey. Not sure you’d want to use this on this particular image.
Note that all these examples are just the color image as shown plus the filter. No contrast or brightness manipulation has been done, so the end result may differ from what you see here. I just think the filters are a good starting point to get you going.
Now, if you want to try this set of filters, you can download them from here: http://www.hoch10.de/bw%20Filters.zip
Try them, play with them, let me know what you think, they’re free to use. I have a few more ideas for other filter functions, so maybe there will be more in the future.