Digital Zone System (Part Five) ~ Tonal Separation In Three Ways

The Digital Zone System that I've written about here on my blog is just one aspect of controlling tonal separation in black and white digital photography.  

There are two other areas of control that I will now take into consideration.  Taken in total, these controls allow for much greater flexibility and ease in monochrome image creation than us old film workers could ever have imagined.

Here are three areas of tonal separation.

• Digital Zone System ~ tonal separation by exposure value
• Luminosity Black and White Conversion ~ tonal separation by Human Perception Modeling
• Color Contrast Management ~ usually thought of as filtration for color separation (as we did when shooting with B&W film)
  

Digital Zone System ~

As I've already covered in depth methods for controlling the Digital Zone System, I'd like to stress just one thing.  Even though I've written a lot about using -1EV as Zone 5, I've found that generating an input correction curve for 0EV as Zone 5 can yield excellent results.  Not the least of which can be a measured improvement in all the work I've done over the years before coming to the realization of the benefits of shooting -1EV as Zone 5.

Luminosity Black and White Conversion ~

While I've written about the benefits of performing a RawTherapee Luminosity black and white conversion, I believe it's worth revisiting the subject in light of the Digital Zone System.

First, I never use simple desaturation.  As readers will recall, Human Perception Modeling shows how viewers of black and white images see the tones of red, green, blue differently.  Desaturation makes the tones of equal energy colors the exact same tones of gray.  I don't want that.

Luminosity conversion from digital color into monochrome takes into account how humans see red, green, and blue.  In short, Luminosity conversion when combined with the Digital Zone System gives us a further improvement in tonal separation. 

Second, there is a color management detail that applies directly to tonal separation in black and white work. In Camera Profile there are several  selections. One is "Tone Curve" and two others are "Base Table" and "Look."  "Base Table" and "Look" manage colors.

With the Digital Zone System I disable "Tone Curve" because I insert control over the exposure value tonal range by applying an input correction curve.

Enabling either a standard or vivid Camera Profile and enabling "Base Table" and "Look" corrects colors at the post-demosaic stage.  This is important.  The process now becomes:

• Apply input correction curve
• Specify a standard or vivid (for increased color contrast) Camera Profile
• Disable "Tone Curve"
• Enable "Base Table"
• Enable "Look"

• Select Luminosity black and white conversion

We now have tonal separation in two flexible, controllable, and measurable dimensions.

Color Contrast Management ~

Now that we have tonal separation manged two ways, Digital Zone System and Luminosity Human Perception Modeling, we can add a third.

Using the Channel Mixer we can approximate filters used in black and white film work.  For instance, we can use a red filter to deepen blues, yellow filters to lighten greens, and blue-green filters to approximate the color spectrum response of Orthochromatic and wet-plate collodion.  Further, there is sufficient flexibility in the Channel Mixer that we can create any filter we want.

The use of these tools is less measurable and more "intuitive."  We can change settings until we like what we see. 

Taken in total, we now have tonal separation in three flexible, and controllable dimensions.

 

Sony A6000, Sigma 19mm f/2.8 EX DN
-1EV as Zone 5 Digital Zone System
Pt/Pd tints applied in processing