Digital Sensitometry for Black and White ~ preamble

Someone noted on my Flickr site that recent in-camera generated jpg black and white images aren't as good as my RawTherapee luminosity curve, mid-tone raised, and channel mixer processed photographs.  

I had to agree.  

The Sony in-camera jpg processor for black and white does things to the tonal range that have been difficult for me to understand.  Contrast quickly shortens the top end of the range and whites are easily blown out.  All too often, the dark tones drag down the overall "look" and "feel" of my images.  Nothing seemed to make sense and nothing was coming our "right."

Frustratingly I've been flying by the seat of my pants and getting mixed results and mixed messages off the 'net on how to proceed.  It's time for a "system reset." 

What I want is a measurable, repeatable, _controllable_, and clearly understandable framework for black and white digital image processing.  Something that reveals what Sony's in-camera jpg processor is doing.  Something that, in a wonderful world, could help me choose a set of operations and settings that match my RAW output.

Being of a certain age, I worked through Minor White's "Zone System Manual - How to previsualize your pictures."  I also briefly read-through Phil Davis' finely detailed approach described in his "Beyond the Zone System".  In general, the Zone System provides a framework of understanding/describing/controlling gray tones.  

Fundamentally the Zone System defines Zone 0 as pure black.  Zone 10 represents pure white.  Zone 5, which is logically half way between the two represents middle gray.  This is often thought of as 18% gray, and it's easy to find, even today, cards of this very specific shade of gray sold to photographers to help in metering a scene.  Further, Zone 2 is described as the very dark gray that still reveals details and Zone 8 is the very lightest tone with details.

The Zone System was incredibly useful back in the day and I shot using that system for several decades.

Could I adapt this system to digital?

So I sat back and had a Deep Think.

Here's the method I came up with (Note: It's not really Rocket Science and I'm sure many other interested parties have already crossed this very same bridge years ahead of me) -

• For each test pass, select the output file type
• RAW - for processing on a Big Machine off-camera
  
• JPG - for observing what the jpg engine is doing when considering ->
  
• Sony "Creative Style" "Black and White"
• Sony "Creative Style "Light" (for a very specific reason)
• Sony "Picture Profile" "Cine4" (for another very specific reason)
   
• Photograph a white surface making individual images from
• -8EV or -7EV through to +4EV or +5EV
• On a Big Computer, measure the tonal values using RawTherapee (or any appropriate image processing software) by
  
• Mousing over the center of the image
• Read the tonal values (found under the histogram in the upper left)
• Make a note of the tonal value and corresponding EV the image was shot at
• Build a chart of EV and tonal values
  

Here's an example.  It is of the very thing that's been driving me nuts.  That is, Sony "Creative Style" "Black and White" at its default settings (Contrast = 0, Sharpness = 0).  I'll talk about what's entirely wrong with this in another blog post.  The problem could be very obvious to old film shooters who are used to thinking in terms of the Zone System, but for now, this simply illustrates the output of the method I just described.

In the next post, I will set the Digital Zone System baseline by working from RAW files.

Note: What I'm sharing in this series is limited to my experience with Sony.  In truth I have zero idea how other digital systems map tones.  But if anyone would like to stop by and let me grab a few photos off their non-Sony systems, I'll buy you a beer.