My books present state-of-the-art information, but state-of-the-art changes with time. In the years after each publication, certain ideas are proven better or worse than previously supposed. Each of my books, therefore, contains certain information that I now believe to be mistaken, or at least I wish I stated it differently.
When this change of heart occurs I call attention to it in the next edition of the book (if there is one) and on the colortheory list. With respect to the latest title, I list known problems here. Up until now, however, they’ve been cosmetic, not substantive: places where I referenced the wrong figure number.
The first real change of heart is a minor one. It pertains to noise reduction settings in raw modules, which is discussed in the second half of Chapter 14. Only the Adobe products, Camera Raw and Lightroom, are covered because I haven’t tested other products enough to be sure that the same conclusions apply.
Sharpening and noise reduction should not, in theory, be done so early in the correction process, because they may pre-empt more effective sharpening and noise reduction later. In both cases the key is to apply as much as possible without going overboard. Oversharpening leaves ugly artifacts. Overcompensation for noise makes the image too soft. The types of things that the PPW does exaggerate these defects. Therefore, if we apply sharpening or noise reduction early, we have to be ultraconservative and assume that we will have to apply more later.
Unfortunately, the early sharpening/noise reduction can make the later moves more difficult. Early sharpening puts in artifacts that can get in the way of later sharpening. Early noise reduction disguises the noise and may make it more difficult to reduce later. Or at least, so goes the theory.
The two topics diverge in two senses. First, every image requires sharpening, but not every one requires noise reduction. Second, although Photoshop proper is very poor in both disciplines, a beginner can still use an action like the PPW panel’s Sharpen 2013 to get a high-quality sharpen. There is no good automated method of noise reduction within Photoshop (some third-party products claim to have it, but I can’t verify this). So, the objection to early noise reduction can apply only to experienced users, because beginners can’t do better anyway.
For these reasons, I made a blanket recommendation that sharpening be turned off in the raw module. It’s never beneficial, and it can hurt by limiting the superior sharpening that can be done later. This is still my recommendation.
With respect to the more complicated question of whether to leave noise reduction on, I stated as follows (Page 402):
I personally keep noise reduction off but I don’t advocate that you do the same without some thought. The default is unlikely to do much harm. It can, however, make it harder for a skilled person to take out noise later, because it attacks certain things that aren’t really noise and thereby disguises the real target.
Uses: If you rarely find noise to be a problem, turn it off. If you never intend to reduce noise manually because you can’t afford the time, leave it on. If you are confident in your ability to manage noise and are willing to take the time to do so when objectionable, turn it off.
Upon further review, I adjust the above slightly. Many cameras have their own noise reduction, leaving us with a problem of softness, not noise. If that describes your situation, then certainly you should turn the raw-module noise reduction off, as it can only make matters worse.
For everybody else, however, early noise reduction can make things better–if we would have to intervene later without it, but using it does just enough to prevent that necessity. It can also, in principle, make matters worse if it confuses things enough that the remaining noise can’t be eliminated effectively later. The question is, how big a problem is that? Is it enough to forego the possible advantages?
In the book, I show examples of how too-early sharpening can hamper things. I have been looking for a similar example for noise reduction: a case where early noise-reduction makes later moves more difficult. I haven’t been able to come up with a case, and I handle raw files from more cameras than almost anybody else. So I conclude that if the problem even exists, it isn’t big enough to outweigh the possible benefit of eliminating the need for any noise reduction at all. The Adobe defaults work fine for me.
UPDATE 22 AUGUST 2014. Upon further experimentation I found two cases where early noise reduction was harmful. Both photos were taken in extremely poor lighting conditions, so they aren’t particularly important in the overall scheme of things. One was a night shot of an amusement park with lots of garish neon creating difficulties. The other was a sea- and skyscape near the Arctic Circle, taken on a very dismal day. Both, naturally, were full of noise when corrected. The early noise reduction spread some of it out rather than eliminating it; the result was harder to get rid of than simple noise would have been. Also, in the amusement park shot the algorithm mistook some of the tiny lights for noise, slightly damaging quality.
Consequently, my new recommendation, as modified 8/14 is: if you never encounter a problem with noise, then you should turn off noise reduction in Adobe’s raw module. Everybody else should leave it on except for photos taken under very poor lighting, and I think that the default values are suitable.
P.S. One of the more powerful Photoshop noise-reduction tools, the Dust & Scratches filter, is also one of the most misunderstood. For a discussion of how it can be used effectively and what its limitations are, click here.