Digital Zone System ~ 0EV as Zone 5 RawTherapee processing example

The prior Digital Zone System posts laid the foundation for actual image processing.  I now share an example of processing a 0EV as Zone 5.

Simplifications ~

I don't want to spend my time metering using a spot meter.  Instead, I let the in-camera matrix metering system do its "thang" as I feel its more than "good enough" for the kinds of scenarios I find myself in.  Using the in-camera spot-meter is always an option in those cases where I feel it would be of benefit to meter more carefully.

0EV as Zone 5 input correction curves work well for 95% of my work.  Scenes tend to be flatly lit.  Often whites slide down the tonal scale and blacks crawl up, which means the tones I want to manage are all on the linear portion of the curve.

-1EV as Zone 5 input correction curves work well for me in high contrast situations, such as brightly lit, strong contrast situations.  In those cases (around 5% of my personal work) I see a benefit for expanding tonal separation in the light areas.  Certainly I can shoot everything at -1EV and process accordingly, but this really isn't necessary (see prior paragraph).  Besides, as ISO rises, so can noise in the shadow areas. 

I put as many settings tuned the way I want into the input correction curve recipe that I've saved from my calculations as possible.  These include Capture Sharpen, vignetting the edges, auto-lens correction, luminance exposure curves, luminosity black and white conversion, and a Camera Profile that interacts well with the luminosity conversion for maximum tonal separation in a single action.

RawTherapee 0EV as Zone 5 Image Processing ~

Opening an Image

 

Essential Elements -

• AMaZE de-mosaic used for low ISO images
• LMMSE de-mosaic is selected for ISO > +/- 1000 (depending on the sensor)
   

Applying Input Correction Tone Curve

Essential Elements -

• Luminosity Black and White conversion
• Luminance exposure curves 1 and 2
• Auto-lens Correction
• Capture Sharpen
• Vignetting the edges to taste
• Camera Profile with "Tone Curve" disabled 

Note: For my work I like Sony Standard and Vivid Camera Profiles.  In concert with Luminosity Black and White conversion they give additional tonal separation, this time in the color dimension (where the Digital Zone System is applying tonal separation in the exposure dimension).

Setting Black and White Curve Points

Essential Elements -

• Watching the histogram to verify where pure white and black is in the image, move Tone Curve 2's end points
• Upper right edge of the curve is white
• Lower left edge of the curve is black

In this example I see by examining the histogram in the upper left corner of the display that the highlights are correctly expressed. So all I needed to do was move the bottom left corner of Tone Curve 2 slightly to the right to get the blacks to turn pure black (again, see the histogram in the above image).

Note:  I realize many software do not offer a second Tone Curve.  In those cases it might be worth exploring other tone tools.  There should be tools with sliders for setting the black and white points.  I don't want to disturb the carefully constructed input correction curve.

Rotation, Cropping and Vignetting

Essential Elements -

• Align the verticals/horizontals to taste by rotating the image (where necessary)
• Crop the image to taste (since I tend to crop in-camera I often just shoot at 4:3 and call it good)
• An overall Vignette is already set in my input correction curve recipe, but...
• Now is a good time for me to dodge/burn or add vignette (as I've done to the bottom of the image in this example)

Adding a Pt/Pd Tone

Essential Elements -

•  I've found I enjoy the tints and tones of Pt/Pd images and have created and stored as recipes a number of tints that I can select from
  

Output Image

Essential Elements -

• For the "internets" is downsize the original image, and...
• I often ask the software sharpen the output once more
  

With relatively few inputs I'm able to generate a rather pleasing image (to me, at least).  Every tone is properly expressed.  Nothing is "blocked up."  The light areas positively "glow."