This is the 9th in a series of Silver Efex Pro 2 posts. Previously
- Overview & Interface
- Image Preview Options
- Global Brightness Adjustments
- Global Contrast Adjustments
- Global Structure Adjustments
- Global Adjustments, Wrap Up (Tonality Protection; Levels & Curves)
- Selective Adjustments
This post covers SEP 2 Color Filters. In the SEP 2 default screen view shown below (click to enlarge), Color Filters are found in the right hand column labeled #5 (there are several other type of adjustments in this same column and they are covered in other posts).
Color Filters and B&W photography – What’s it all about?
B&W images are nothing but gray tones. In order to make one gray tone stand out from others B&W film photographers used color filters (typically glass which was placed in front of the camera’s lens). What does a filter do?
A filter transmits light of its own color and holds back light of other colors
- “Transmits” equates to allowing more light to strike the film > resulting in greater exposure > giving lighter shades of gray
- “Holds back” equates to allowing less light > less exposure > darker shades of gray
and so, for example, if we wanted to make our blue sky darker we’d use something like a red filter (a blue filter would make the sky lighter, not darker). That’s all there is to it. Rocket science it’s not.
We can use SEP 2 Color Filters in exactly the same manner – to the same effect – as traditional glass color filters were used with B&W film. (And, of course, you can still use a real glass filter with a digital camera in the same way – but why bother since it can be done cheaper, easier and with greater flexibility in post processing.)
Visit this Tiffen Filter website for examples.
Click on any image in this post to enlarge it.
The image below is section #5 (SEP 2 Adjustments) from the above interface screen shot – after expanding the Color Filter section.
This allows us to create the effect of any filter made – and some that were never made. We apply a filter to our image by choosing both a color (hue) and a strength. This can be done either by –
- Using a “canned” preset filter from the top row. The six circles represent neutral (no filter), red, orange, yellow, green, and blue – a typical set of filters carried by a B&W film photographer.
- “Roll your own” by selecting a Hue & Strength using the sliders.
Here is a simple example image I’ll use to illustrate color filter effects – top is the original color and bottom is the SEP 2 default (neutral) preset. Subsequent images will show the change to the default B&W image as a result of applying each of the preset color filters.
Neutral color filter preset – no effect (same as clear glass). Note the change that presets cause to the Hue & Strength slider throughout this series of examples (no change here; it’s neutral).
Red preset top & neutral bottom. The red is lighter than it would be normally and the other colors are darker (recall that the filter transmits light of its own color and holds back other colors)
Green preset top & neutral bottom. The green is lighter than it would be normally and the other colors are darker (recall the filter transmits light of its own color and holds back other colors).
Blue preset top & neutral bottom. The blue is lighter than it would be normally and the other colors are darker (recall the filter transmits light of its own color and holds back other colors)
How about the orange and yellow – two colors that don’t appear in our three color test image? (or do they?) Recall that all colors are can be created from some combination of red, green and blue – so both orange and yellow each have some elements of the three “pure” colors that we see in our image. That said, the orange and yellow preset color filters will have an effect in proportion to their proportion of the “pure RGB” triad. Take a look – both have shifted in tone from the neutral display at the bottom.
Let’s take a quick look at the effect of the strength slider. Set to zero it causes a filter to have zero effect (neutral, clear glass). As we change the strength to ever higher values, the filter transmits more & more of its own color (and holds back more of other colors). Here’s an example using the red preset from above.
Here’s the preset. Its strength is 66%.
Here’s the same filter but with its strength increased to its maximum value of 200%. The red (left) section is pure white (totally overexposed) while the other two colors are pure black.
One more slider variation. This one compares changing hue. The top image is from the blue preset shown earlier. The blue preset hue value is 240. The lower image show the gray tone shift if the hue is changed a small amount – to 250 from 240. The change is most apparent in the red/green sections which have gotten darker (if your monitor is calibrated properly).
and how about if we increase the strength to the maximum? No surprise, the blue segment is now pure white and the others are black just as we saw with the red filter above.
Let’s take what we’ve learned about SEP 2 Color Filter adjustments and see how it translates to real world images and not the test image.
We’ll use this image – input at top and SEP 2 default (neutral) B&W conversion at the bottom.
Let’s begin with what might seem an obvious choice – a red filter to darken the blue sky (neutral top & filter bottom). This uses the SEP 2 “canned” red filter as shown on the right of this screen shot. Note that besides darkening the sky, which was expected, there is a lightening of other elements such as the barn (due to their, not obvious, red components). For what it’s worth, also note the change in the histogram as compared to the default conversion shown above.
Here’s what other filter colors do to this image –
Blue – blue sky got lighter as expected (top neutral, bottom filtered), and look at the barn…. This isn’t the filter you’d want to use for this scene and you can bet that Ansel never did.
Yellow -This one works well for this image – better than either red or blue IMO (top neutral & bottom filtered)
Just for the heck of it, let’s use the red again but this time at maximum strength. Now that’s a dark sky.
That’s it for the SEP 2 Color Filter Adjustment. Next – Film Types.