The previous entry described giving each of five independently corrected versions 20% weight to create a new, “par” version. This can be called a “stupid” blend, in that no notice is taken of the merits of any of the five. Nevertheless, it appears that this average is better than all five of its parents in a surprisingly high minority of cases. The apparent illogic of this finding gave rise to discussion on the colortheory list and prompts this supplemental post.

Recapping: in a well-funded study, scientists from MIT and Adobe gathered 5,000 images and hired five knowledgeable students to correct each one of them, using Lightroom. All the originals, in DNG format, and the corrected versions have been made freely available. I chose 100 of these images at random and corrected them myself using PPW principles and restricting myself to procedures that could be automated. Also, for each of these 100 images I created a “par” version, the “stupid” average of the five student corrections.

This post will examine three very different images, starting with the originals as given to the retouching group.

Half the value of these exercises is in predicting what is about to happen, and then discovering whether the prediction is correct. Usually it is, but as we will see in this and other posts, sometimes surprises pop up. Here’s how I felt about these three before beginning.

*The tattoo image, #1859, is not as hard as the desert exercise shown in the previous post. Viewers, however, are notoriously finicky about fleshtones. The retouchers are likely to concentrate more on making the tattoo stand out and may have varied ideas of how to present the skin. The par version will arrive at a consensus. I think that this may be one of those where the par version is better than any of the five. I expect that my own version will win decisively, because PPW’s MMM action can introduce color variation in skintones in a way that does not exist in Lightroom.

*I am also planning to win decisively in the aquarium nightmare of #4976, but for a different reason. I believe that PPW has somewhat effective tools to attack this mess. Whether Lightroom has anything like them is irrelevant, because giving this original to a nonprofessional group is a form of sadism. Chances are that the five corrected versions will go in every possible direction and none of them will be acceptable. I therefore think it’s a sound bet that the par version will be better than all five parents.

*The girl in the pink sweater, #0002, is a nearly total opposite. For a change, the original version is not bad; I wonder how many of these five retouchers, in an attempt to justify their own existence, will make it worse. It doesn’t have features that make it particularly appropriate for PPW, although I hope to get by on my good looks and personality. There probably won’t be too much variation among the work of the five retouchers so it is questionable how the par version can be much better.

We commence hostilities with the tattoo image.

Those who read the previous post recognize the similarity. The first two versions shown have drastically different ideas about image weight. I have no clue what retoucher A was thinking, his work is worse than the original. What retoucher C did makes more sense, in lightening the skin the tattoo stands out more, but he went quite a ways too far in my opinion.

Naturally, when averaged, these two errors will to some extent cancel each other.

Again like the previous posts, two better versions that still tend to even each other out. Like retoucher C, retoucher E lightened the skin but in doing so weakened the tattoo. Retoucher D took a different tack. He somehow darkened the tattoo itself. In doing so, a certain amount of color was lost. Not a bad concept, but I prefer the PPW approach, which would be to move all colors in the tattoo away from orange, to better differentiate them from the skin. So, instead of making the red parts darker as in 1176-D, they should become rosier.

Again as in the previous post, one of the five retouchers comes up with something close to the consensus, and once again it isn’t as good as the “stupid” weighted average. How can this be? The par version is picking up some of the strengths of each, and largely discarding their weaknesses.

On, now, to my boneheaded prediction that my version would be much better than anyone else’s. This kind of blunder is what happens when one sees only one part of an image and forgets the objective. When I looked at the original I saw a lot of skin. My experience is that whenever there is so much skin PPW always does better than any alternative approach, because it adds attractive and believable variation. As I will show in future posts, PPW has a massive advantage in portraits. And in fact, if this person had no tattoo, I believe my version of the back would be considered decisively better than the others, which would seem totally boring by comparison.

Unfortunately, the image does feature a tattoo, which is going to be focus of the viewer’s attention. Putting this much action in the skin does make it look more natural but it is also a distraction from the whole point of the image.

A previous post outlines how I report the results of comparisons of my versions against the par. Here, it wouldn’t matter how a vote went. The question is, would everyone agree that a straight 50-50 blend of the two would be better than either parent. In this case, I think that the answer is clearly yes. This competition is therefore a tie. We move on to the group’s efforts to grapple with a greased pig.

The above version is unlikely to find favor with the subject.

Essentially the above two are a concession of defeat, a decision that it’s time to move on to the next opponent.

Progress is being made, but at too high a price. Both of the above have overly orange skintones. Retoucher E got excellent detail in the face at the cost of obliterating the aquarium.

Little discussion is needed. The exercise was too difficult for the retouching group. Nevertheless, the par version, the average of their terrible work, is much better than any of the five parents. The PPW version, though, rates as a “decisive win” over the par version. By definition this means that it would be almost universally preferred at a glance.

Averaging minimizes the effect of mistakes. Be aware, though, that it also minimizes the effect of really good work.

Retoucher A did a better job with this image than I did, a relatively rare occurrence. When it happens, it indicates outstanding work on the individual’s part, probably much better than that of his four colleagues. It strongly suggests that it is therefore better than the par version.

So be it here. The par version is shown beneath the two, along with a repeat of the default version for reference. I can scarcely tell the difference between the par and the default, the par made the girl’s hair slightly lighter, a good thing. But clearly the other four retouchers, whose work we haven’t seen, dragged the average down. In fact, some or all of them must have made the original worse, a bad idea in color correction.

How do we score this? Well, 0002-par and 0002-a obviously have the best shape. The standard when comparing my work to that of an individual is whether mine is “significantly better,” which it is not. There is no need to inquire whether it is significantly worse.

The more careful comparison is between mine and each par version. I prefer mine here, because I don’t object to very pink skin in children. I also prefer mine to a 50-50 blend of the two. However, the rules also provide that when 100% of the color of one version is married to 100% of the luminosity of the other and the result is better than either parent, then the contest is a tie. And that is the case here.

Summing up the lessons of these two posts.

*We have not considered “intelligent” blending where the goal is to combine the best parts of two or more versions rather than a mathematical average that takes no account of their good and bad features. Such intelligent blending is very powerful, but somewhat difficult. I have provided examples of it here and here.

*Nevertheless, “stupid” blending is unexpectedly effective. It tends to even out color issues; its handling of detail is not so impressive. But in this study of 100 images it was really striking how frequently the par version had better color than my own even when the color of each of its five parents was bad.

*If you’re baffled as to how to proceed with a difficult image, try several careful versions. None of them may be any good by themselves, but to the extent that they agree they will create a better final result. The aquarium shot above is an example. Nobody got a good result, yet the averaged version is acceptable.

*An averaged version is conservative by definition. This makes it valuable to PPW practitioners, who often create files that are too loud. In the desert image of the previous post, in the tattoo at the top of this one, and in the little girl we just saw: in all three of these, if I had had access to the par versions when I finalized my own, I would have made use of them, by blending in some of their color (not luminosity).

*For all these reasons, I reiterate my recommendation that people should routinely make extra versions, even if it means spending less time on the primary version. These extra versions should be done as quickly as possible. We have seen in these two posts that the versions don’t have to be very good in order to be useful. You should be able to rattle them off in a minute or so. The potential loss is one minute in case the version is a complete bust. The potential gain is considerable.