Image Quality? Image Depth.

In the previous post I pointed you to Mike's remarks over on ToP, which, if you have not, you should still go read.

This may or may not be an accurate paraphrase, but it's what I think he said, and what I want to think about now:

Image Quality isn't a real thing, as an objective measure of goodness in any meaningful way. Photographs simply have properties, which are neither good nor bad, they simply are. There is no use to be gained by assigning subjective qualities to these properties, such as sharpness, dynamic range, contrast, saturation, and so on and so forth. These are certainly measurable things, but we should not use them to measure the quality of the image in any way.

This is a point I have harped on at some length, although not quite in these words. The image exists as it is, and these technical properties either serve and support the image, or they do not. If they serve and support the image, we could describe them as good, to be sure. However, the exactly opposite quality might serve and support a different image. Simply measuring something like sharpness yields no insight into the goodness of the image. Sharpness is neither good nor bad by itself, it is good or bad only in the context of a specific image.

So far, so good. This has all been said before. In fact, this next part has been said before as well, but perhaps not quite in this context.

Photographic properties come in three flavors, for my purpose here:

• Properties which can be altered in post, but only "uni-directionally" for lack of a better word. I can remove sharpness, I can remove color, but it is difficult to add sharpness or color when it it not present.
• Properties which can be altered "bi-directionally" in post. I can alter apparent contrast or saturation in either direction.
• Properties which cannot be meaningfully altered in post. Things like the relationship of the various objects in the frame, the expression on the subject's face, the position of the key light.

Of course what I am saying here is not strictly true. With enough effort you can do pretty much anything to a photograph in post. Further, as I have noted, the line between what can and cannot be done in post is constantly moving (for example the light field camera allows us to focus in post). In broad strokes, though, there are these three families of properties.

What does make sense is to lump the first family of properties together into some sort of named bucket. It is a fact that a camera which produces higher resolution images is a more flexible tool than one which produces lower resolution images. Is the phrase "image quality" a good one to use here? I agree with Mike, essentially, that it is not. The phrase sounds too much like "good photograph" which is a completely different thing almost entirely concerned with the third family of photographic properties.

Perhaps we can measure things like sharpness, dynamic range, color gamut, and so on (in general, the things we can alter only in one direction in post, given the tools of today, whenever that is) into something called "Image Depth" or "Imaging Potential" or similar.

The Online Photographer

Once again, Mike nails it. Read it, know it, love it. It's everything I believe in, it's everything I think you should, too.

You Gotta Know The Rules To Break 'Em

You have to know the rules to break them. I've addressed this bit of conventional wisdom before, but my thoughts have been refined on this point.

You do not, strictly speaking, have to know the rules first. What you need are two things: a grasp on the problems that are solved by the rule, and another solution to those problems.

The rule of thirds is truly about placing things off center, to create a livelier visual result. Various rules about portraiture are, mostly, about creating a flattering look, avoiding making the subject's nose look too big, and so forth. Perhaps your approach to portraiture plunges the nose into darkness, so it's OK if it's too big. We focus on the eyes, perhaps, because as animals we're most interested in the eyes of other animals. By creating or observing an equally interesting element, we might focus on that element instead of the eyes -- the main thing here is to not focus on something random and uninteresting. And so on.

Knowing the rule, therefore, is perhaps nice, but knowing what problem the rules solves is essential. You might well grasp the problem without knowing the rule in the first place.

Solve the problem, don't worry about the rule.

FSA Photo of the Week

Something a little more timeless?

The Histogram

Another favorite tool of the Internet Expert is the histogram. They like to show you the histogram of your photograph and point out features of it to explain to you why your photograph sucks.

Ignore these people.

In fact, ignore the histogram, for the most part. It can be a useful learning tool, but it's really not showing you anything that is not blindingly obvious in the image, so learn to see the image instead. By all means, compare with the histogram a few times, until you can pretty much visualize what it will look like for any image. This should take a very short time.

The only other time the histogram could be useful if for checking your images as you shoot. The histogram just tells you what your photograph looks like, after all, but sometimes it's pretty hard to tell what your photograph looks like when you're peering at the back of your digital camera. So, consider looking at the histogram instead when it's hard to see the image.

Anyone who tells you that the histogram has to start at the bottom and go all the way to the top is a twit. In the first place, they're gabbling away in technical terms about something that's extremely obvious visually -- a full range of tones, from blacks to whites. Presumably they're being technical to make themselves sound smart, or because having finally understood the histogram they think it is important. In the second place, it is simply not the case that every image needs black blacks and white whites. The tonal range has a profound effect on the mood of the image, and sometimes you want one of the other ones.

Of course you should think about the tonal range of your photograph, and what the emotional impact of it is. Adjust to taste. There is no "right answer" here.

FSA Photo of the Week

I may as well just define a week to be 8 days long.

Technology and New Ways of Seeing

In my HDR Manifesto, I proposed that a relatively recent technology, HDR and tonemapping, could be applied to create a new aesthetic vision. This has happened before.

Street photography was enabled by two things, fast film emulsions and the Leica camera. Without the fast emulsion you couldn't freeze motion in the necessary way, and without the small 35mm camera first available in the form of the Leica, you could not be discreet enough to accomplish the "street" way of envisioning the world. The essential new idea in "street" is the notion of an image which is present only for an instant, the momentary coming-together of things in motion (usually people) in a fortuitous way to be an image worth shooting.

Prior to "street" as "street" we have many urban scenes. Some of the earliest photographs made were of city streets, but they were not "street", envisioning the world instead in a painterly way: here is a street, it is picturesque, or otherwise worth recording. I will wait until the light is so, and then I will set my camera so, and I will record this street. This is a fine way of seeing and working, it produced many excellent photographs. It is how landscape done. These photographs were not "street" in the way we understand it today.

I maintain that the very idea of "street" was a new and essential thing -- before this, it had never really occurred to artists that there could exist these fleeting compositions. Things either were or were not good compositions. It is this essential idea of the instantaneous composition of people going about their business, a composition here and in the the next moment gone, that defines and motivates "street". This idea would have been difficult to even conceive without the Leica and without the fast film emulsions of the early to mid 20th century.

In the same way, creating an image without a strong key light is largely inconceivably to photographers of my era, photographers who learned prior to the techniques of HDR. Most practitioners of HDR are simply in love with the process and the look, they are creating images which please them are their cadre. This is fine. They are, I think, missing what the truly have in their hands, which is a technology that truly enables a new way of seeing, a truly new aesthetic, in the same way that the Leica enabled the idea of the instantaneous composition that is "street."