Some Thoughts on Google/NIK Silver Efex Pro 2
I initially discovered, and started using, Nik Silver Efex Pro 2 probably close to a year prior to Google purchasing the entire Nik product line. And once I became somewhat familiar with the package, I came to believe it was the "cat's meow".
One of the tools in the package I found particularly helpful was the Zone System Map available via the 'Loupe&Histrogram' option at the bottom of the tool palette on the right of the SFX Pro window. Select the Histogram option there, and the Zones appear immediately below. Check the box to the left of the numeric Zone values, then hover over any of the individual zones and the portions of the image that fall into that zone display a 'selection mask' in the image window. Pretty cool stuff that I referenced fairly frequently when working on an image.
But the longer I used SFX Pro, the more I began to suspect there were occasions when some awkward tone compression might be occurring. I noticed it primarily in the deeper shadows. And the closer I watched, the more it became apparent there were instances where I was losing detail in shadow areas that was present when I initially brought the image into Photoshop via Adobe Camera RAW.
As a result, I decided to do some testing to determine, in RGB value terms, what RGB value was needed to have SFX Pro read it as a different zone. I.e., in RGB terms, '0,0,0' represents pure black, '255,255,255' represents pure white, '128,128,128' represents middle gray, etc. My goal was to determine where, if pure black was 0,0,0 and the starting point for Zone 0....what RGB value was needed to have the package read it as Zone 1. And once the starting value for Zone 1 was determined, determine the first higher value that pushed the system to indicate a Zone 2 read. And continue the same until the initial RGB value for each Zone had been determined.
The image below illustrates the results of that testing. For example, the 4th circle from the left represents Zone 3, and the first value I could fill that circle with to cause the s/w to display it as a Zone 3 value was RGB #49,49,49.
Having gone through that rather tedious exercise, I'm left trying to understand how, or even IF, all this data is just interesting but useless data, or is there actual information here that may help the conversion process.
I never did find a means of making use of the info, and have since moved on and no longer use SFX Pro for my B&W conversion. But decided to go ahead and post this now as a reference for those who still use the package.
Things I did notice.....
- On my calibrated monitor, Zones 0 & 1 are indistinguishable to my eye. Same with Zone 1 & 2. Looking at this .psd file of this image in Photoshop (rather than the compressed .jpg displayed here), I can distinguish between Zone 0 & 2, but even that diff is minimal.
- The range of RGB values that map to each Zone is more variable than I'd anticipated. For example, Zone 0 is comprised of only 3 RGB values, Zone 1 comprises 10 RGB values......while Zone 3 covers 32, and and Zone 7 covers exactly 30.
- It's interesting to note that the number of RGB values that comprise the brighter end of the Zones are not nearly as narrow as those in the lower Zones.
- It seems my original perception that I was losing shadow detail in some images was probably an accurate one. I didn't test, but am fairly confident in thinking there were areas in the image as it came out of ACR into Photoshop that probably would have fallen into Zone 3 at that point, but were compressed into the lower end of the Zone 2 range, or possibly even into the higher end of Zone 1 while working in SFX Pro.....or something along those lines.
In the end, I'll leave it to other users of the package to determine if any of this information is of value to them in converting images to B&W. As mentioned, I have since quit using Silver Efex Pro. It remains a good package, but with Google having turned it into a free, but unsupported app (along with the entire Nik suite), there is little doubt it will, at some point, start breaking down and eventually quit working entirely. And that only because Adobe will eventually update/change some piece of Photoshop on which the Nik products rely heavily for their functionality. And when that occurs, users will be stuck finding a new B&W conversion workflow. I simply decided I didn't want to have to make that change 'on the fly', and have developed a new B&W conversion process that relies almost exclusively on Photoshop & Camera RAW.