Saturday, June 22, 2013

Wishes Granted!

A WHILE BACK, I wrote two articles listing things that I’d like to see in some future version of Photoshop:
Now some of the things I wrote are rather confused or unclear, but I did see a real need for them at the time, such as:
Each color channel has a maximum value of 255, a minimum value of 0, and we can use only integer steps between: 1, 2, 3, and so forth, with no intermediate values. This lack of precision is of little consequence to most users, and if you do need greater precision — for example, if you are applying severe curves to your image — then certainly you can use 16 bit mode (as I do) to increase the number of possible values. This extra precision helps avoid digital processing artifacts such as banding, and also lets you get better shadow detail…

But that isn't good enough. I'd like to see fractional RGB numbers. I want RGB values greater than 255. I want negative RGB numbers. But this is madness! You cannot display an image with RGB values greater than 255! And what on earth are negative RGB values? Those are clearly impossible, there is no such thing as negative light!
OK, for a final image, it needs to be in some specific, bounded color space that can be reliably displayed or printed on various devices, and for the time being, the best color space for images is usually sRGB, at 8 bits per color channel, using the JPEG file format, since those standards are supported by nearly all computer monitors and desktop printers. But when you are processing an image, there very often is a temporary need for values that exceed the bounds of any particular color space:
For example, when I apply a severe curve to an image, anything that ought to go over 255 is set to 255, and so we lose information and image detail. However, if its value ought to be 300, I want it to be 300, even though it is out of the gamut for the time being. If I tell Photoshop to make an image twice as bright, I want the entire image to be twice as bright, without worrying about losing highlight detail. I will deal with the gamut when I need to deal with it, which is when I’m preparing the final image for print or web display…

This brings us to negative RGB numbers. These in fact can represent real colors. For example, if you work in a narrow-gamut color space similar to sRGB, and you want to represent a real color outside of its gamut, you can mathematically represent this if you are willing to allow at least one RGB number which is negative or greater than 255. So a negative RGB does not mean negative light, but rather that it is merely an out-of-gamut condition. If we are allowed to use negative numbers — and numbers greater than 255 — then we will be able to represent all colors while still using a system that is otherwise identical to our narrow-gamut color system. This system will remain relative to a particular gamut, while not being limited to that gamut.
There were a number of other things that I wished for, including:
3. Photoshop does not resize images well, and often generates interference patterns. Lots of research has been done on these kinds of algorithms, and it would be good to see these better solutions in Photoshop…

5. When you use curves in RGB, you can either do it with the Normal blending mode, which typically causes an increase in saturation, or you can do it with Luminosity blending, which decreases saturation. How about a simple method which does neither? I just want the tonality to change, not the basic coloration…

8. I’ve noticed that there is a distinction between chroma, colorfulness, and saturation; not really sure how or what Photoshop does. A solid colorimetric model would be useful…
Now for the last month and a half or so, I’ve been working on my next book, which is due out this fall, and so I haven’t been posting here since I was rather busy. But during my photo processing, I’ve ran into problems related to all of these wishes mentioned above. I was working with scenes that had tremendous dynamic range, and so I took multiple exposures — sometimes five separate images or more — and had to blend them together so as to create an attractive and plausible final image. The software I was using to blend together these images often would over- or under-expose my images, or would often create odd shifts in color, such as turning reds to orange and blues to purple.

I also had to add severe curves to images, do strong brightening of shadows and extreme pulling back of highlights, and all of these photos ultimately had to be converted to the CMYK color system so that they can be printed on commercial press.

I also had to use a good resizing algorithm that would retain image sharpness without aliasing artifacts. And so I used the comprehensive ImageMagick utility, as I had on my two previous books. Even though it is a difficult-to-use command line interface, my workflow is smooth, if a bit error-prone if I’m not careful. The particular algorithm I use seems to produce sharper image when downsizing an image greatly, reducing the need for additional sharpening as an image gets smaller.

With regards to image sharpening, this is best done on a linear image — that is, one where a gamma correction has not been applied —  but Photoshop only allows me to do this in a clumsy and unsatisfactory manner. I had to use at least 6 different sharpening methods because of one difficulty or another. By the way, I think sharpening is an important technique that can really use some more research.

Since my first book, I used the enfuse software package — which is another UNIX command-line utility — to blend together multiple exposures, but it was having trouble with the huge dynamic range of my subjects, far greater than what I had used before. Important, bright, saturated highlights were being overexposed, or my shadow tones were turned to pure black, often with strange artifacts. I also had severe color shifts. As this is a critical component to my workflow, I went to the product developers, who graciously helped me out with this, and even provided me with a new build that overcame some problems I was seeing.  As it turns out, I was using features that should not be used with images that have a gamma correction applied, and the new version supported images with gamma.  Also, the package can do blending of colors using the CIECAM02 color space — a model of color based on the properties of human color vision — which leads to more visually accurate results.

I use a number of camera RAW file converters, simply because each converter has its strengths and weaknesses, and some images — for whatever reason — fail to convert well with one package or another. As I was busy processing my photographs for the book, I found out that none of my RAW converters worked on some images, giving me unappealing photos:  extensive detail in the shadows or highlights were damaged no matter the setting, or colors were lost, or no adequate white balance could be achieved. It was a desperate situation, and I looked around for alternatives.

I rediscovered the Raw Therapee product. I downloaded it some years ago, but didn’t see much that interested me. But now, in my desperation, I needed something that would work, and so I got the latest version. Finding the user interface complex and not intuitive, I read the manual. As it turns out, many items on my wish lists are featured in this product, and it did what I needed it to do. Every problematic photo was processed easily and successfully by this product. Wishes granted.

At a bare minimum, I would like an image to plausibly look as I remember seeing the scene. Almost always I can see detail and saturated color in bright highlights, and I can see texture and color in almost the deepest of shadows in the real world. Granted, some scenes have so much dynamic range that some  sort of HDR photography is called for, or supplemental lighting, but sometimes I have problems photographing scenes with flat lighting; for example, brightly colored flowers often produce problems. For my book, I often had bright saturated red colors which rendered poorly, with the red colors rendering without much texture, or where they shifted to an orange color even though the white balance was adequate.

As mentioned, I would like an image to look as I remember seeing the scene, at least as a starting point in my processing. But this high expectation usually can’t be matched by standard camera JPEGs, and using RAW files is sometimes problematic as my experience with the various RAW converters demonstrates. Even if I do want to adjust the tonality of my final image for effect, I almost never want blown highlights and plugged shadows, but I find these defects even in scenes with flat lighting.

There is one critical step in RAW processing — either in the camera or on the computer — which can harm the final image.  No camera perceives colors like the human eye, and one way the camera approximates human color perception is via a blunt instrument: a color matrix is a transformation of the RAW pixels, where the various color channels are multiplied by factors and added and subtracted from each other to approximate visual colors: see the article Examples of Color Mixing for an example of this. This addition and subtraction can easily force pixels to be either zero or to 255, which causes loss of texture.  More complex way of converting the colors, using look-up tables (LUTs) or parametric curves, while giving more accurate color (up to a point), can harm an image in unpredictable ways, and may even put a cap on the quality of a conversion.

This color conversion is mainly done these days via ICC profiles, a series of standards promulgated by the International Color Consortium. Adobe, however, uses its own profiles for its products. Not all profiles are created equally, even if they are all theoretically for the sRGB standard. Some profiles generate more noise than others; some will frequently clip highlights or plug shadows.  For example, if you examine the blue color channel of a digital image, you might be dismayed as to how noisy it is; now part of this noise is simply due to the facts of digital capture, but the RAW conversion itself can generate large amounts of noise itself if a malformed profile is used, or if inadequate precision is used in the mathematics of the transform. You read about this phenomenon in the article ICC Color Space Profiles and Blue Channel “Noise”; here we see that “noise” can simply be artifacts of color conversion, which leads to loss of texture in the final image. I’ve seen these kind of artifacts in my own experience in RAW conversion.

RawTherapee uses high precision mathematics when converting a RAW file — it uses 32 bits per color channel as a standard, and it optionally can go to 64 bit per channel — and it attempts to use high-quality custom profiles for rendering the final image. It also allows unbounded calculations: even if an image is destined for the sRGB color space, if a particular pixel needs to go outside that color space temporarily, it will go outside, without being clipped. Enfuse also uses unbounded, high-precision mathematics for its calculations.

Like Enfuse, RawTherapee now optionally uses the comprehensive CIECAM02 color space, which allows for visually precise manipulation of color and tone levels. It separates color from tonality in a way much more satisfactorily than the RGB and Lab color spaces used in Photoshop.

It appears that most of my wishes have been granted in a way, although I must admit that these software packages lack the polish of expensive commercial software like Photoshop, and due to my time constraints, I have large gaps in my understanding of them and undoubtably are not using them optimally.

A while back, I decided that I was too concerned with camera gear and photographic technique, and that instead I needed to concentrate on more universal artistic concerns, such as composition, color, lighting, and mood. But it was precisely at that moment that a large number of technical roadblocks were placed in front of me, and I was forced to get an understanding of imaging technology before I could concentrate on to the other things. Ironic, yes? But this should be expected. Western culture, unfortunately, has developed an ‘art versus science’ mentality — and this disease is spreading to other cultures because it is thought to be progressive — but that was not always the case in the West. Rather, art and science are merely two aspects of the human person, and these ought to be joined together so as to produce fruitful offspring.

My concern with all this high technology was so that I could get pleasing final images, and my existing technology failed in that purpose. But high precision mathematics can lead to artistically precise images and unbounded calculations remove bounds from artistic intent. It is all a part of one process.

Saturday, March 16, 2013

Brief Advice on Learning Photography

SOMEONE WRITES “I am buying a new camera, but cannot make up my mind…” The correspondent then lists a number of expensive recent-model cameras, commenting on various technical features, and why one might be more suitable than other for his stated purpose of taking photographs of sports, and of wildlife while hiking. He states that he is a beginner.

A camera purchase can be an agonizing experience, especially given the choices available.

When I first got into digital photography, back in the year 2001, I spent hours going over the reviews, and ended up getting a very expensive camera, one which was a top-rated camera back in those days. I wanted a camera mainly for taking nature photos while hiking.

I was extremely disappointed in my photographs, and wasn't able to return the camera for a refund. That disappointment killed my interest in photography for a number of years.

Later, only when I needed to deliver good-quality photos, did I learn about photography, and so I discovered that my ‘bad’ camera was actually pretty good, especially after I learned the basics of composition, white balance, and exposure. Also, I learned to overcome some poor features of the camera with the right post-processing software and techniques.

Be aware that the newest cameras today operate in a similar manner to cameras decades old; and old problems such as the color of light, and the basics of focus, exposure, and shutter speeds haven’t changed. Newer cameras won't do the thinking for you, although they try sometimes. Don't expect that a camera will make your photography good.

If you are a person who tends to get buyer’s remorse, then I would not suggest spending too much money on something, even if reviews and people like me strongly recommend it. However, I would avoid getting something that lots of people criticize. Rather, look for good values.

Until you know what you are doing, you are merely guessing at this time. Don't worry too much about it, we've all gone through it. Here are some suggestions:

  • Obtain or borrow an inexpensive camera, maybe one that is used. A super zoom camera might be good, or an older, used DSLR with a good zoom lens. If you are worried about making the right purchase, then spending only a little money on something OK might be better than getting an expensive camera that will be disappointing.
  • Go out and shoot lots of photos with it, under a variety of conditions, of various subjects.
  • Simultaneously, learn the basic theory of photography: exposure, shutter speeds, aperture, ISO speed, focus, etc. Learn the basics of general visual arts theory: composition, light, color: find good photographs and paintings and study them; find out what makes them good. Learn how to use your camera; don’t try to make lots of adjustments to your camera at first.
  • Get feedback from your images. You can post photos on the DPreview forums and other places. It is most important that you post disappointing photos there, and ask why a particular photo might be disappointing. You are likely to get excellent feedback if you present a problematic photo and ask for advice for improvement.
  • Take the advice and experiment some more. See if your photos are less disappointing.
  • Find a fellow photo hobbyist or club and go out shooting with them, especially one who is more experienced.
  • I would not post photos on forums that you think are really good, expecting praise from others. Very often I’ve seen beginner photographers post photos, saying “look how great my photo is,” and they end up being savagely criticized. This is the nature of the modern artistic ego which seeks perfection: a thick skin is needed at times. A measure of humility is needed: rather, post a photo and ask for suggested improvements. Eventually you might be surprised and get lots of compliments.
  • Learn the basics of post-processing on the computer. Beginners tend to become enamored of special effects, but instead try to thoroughly learn the basics of levels, contrast, white balance, resizing, cropping, sharpening, etc.
  • Once you gain lots of hard-earned knowledge and experience, then you will pretty much know what kind of purchases you will need in the future.

Many beginners go through a phase of loving the photographic process, first placing lots of emphasis on gear, and then later on techniques. That is natural. But always keep your eye on the final purpose of photography: making good photographs.

Monday, February 4, 2013

The Amateur, the Professional, and the Artist

A BEGINNING PHOTOGRAPHER ASKS: Am I an amateur photographer? The questioner also asks if the quality of his work shows that he is an amateur.

Well, in answering questions of this type, it helps to first define the terms. Usually, we distinguish between amateurs and professionals: some photographers are definitely amateurs, and others are certainly professionals.

The vast number of photographs are taken by ordinary people who have no particular connection with photography other than a desire to capture memories and images of loved ones, and so we can only call them photographers in the loosest sense. On the other hand, there are people who are most definitely photographers. What follows are distinct types of photographers and may not precisely correspond to individuals, rather, they are illustrations of largely mutually exclusive types which may be present in varying degrees in every photographer at any given time.

The Amateur

The English word ‘amateur’ comes from the Latin amator, meaning ‘lover.’ In the best sense, an amateur photographer is one who loves photography, and in older literature this basic aspect of loving the art form is quite clear. If the questioner loves photography, then he is most likely an amateur.
An amateur will spend countless hours learning and refining photographic techniques, often by taking numerous photos of the same subject, even brick walls, and he often spends more time reading about photography and visiting camera stores than actually photographing. The amateur photographer constantly reads camera reviews, is uncertain if his camera is good enough, and thinks that some upgrade or gadget will be the magic bullet that improves his photography. When shooting a scene, the amateur agonizes over his camera settings, and fumbles with the controls, often keeping his human subjects impatiently waiting. While the amateur may reluctantly volunteer to take some important pictures for friends and family, these pictures can end up being disappointments because of the amateur's uncertainty and fear.

But the amateur loves every bit of time he spends on his hobby, even to the point that he pines away in pain when he is not doing it. He may nearly drool over camera reviews on the Internet, and his heart palpitates as he unboxes his new, finely shaped, and aesthetically pleasing camera — for which he paid far too much money. As most lovers know, pursuing the object of love can be seemingly irrational, obsessive, all-consuming, expensive, and even heart-breaking.

I see no reason why an amateur photographer should be expected to produce good photographs, because perhaps the amateur loves photography — the art itself — instead of the final photographs, which are the works of that art. It is a subtle, but significant distinction, enjoying the technique and tools of photography over the fruit of these. But as children are sometimes unexpectedly produced by young lovers, an amateur photographer may occasionally produce a good image.

The Professional

The English word ‘profession’ comes from the Latin professio, where it means, among other things, ‘a business or profession which one publicly avows,’ and this is the main current sense of the word. So a professional photographer is a photographer who does his work for the public instead of just for himself.

The business of photography is mainly the art of selling and delivering photography and photographic services to the public. There are many professional photographers who consistently deliver the goods in a timely manner at a good price. These seek out clients, and give them what they pay for with no excuses or delays. They tell everyone they meet that they are a professional, and offer a wide variety of services, usually agreeing to give the customer what the customer wants. Working with them tends to be straight-forward or even pleasant. The majority of the professional's time is likely not spent doing photography, but rather doing those things that all businesses do, including marketing and sales.

I see no reason why a professional photographer should necessarily be expected to produce outstanding photographs, for their main job is selling photography. They simply need to produce good enough work at a proportionally reasonably price, and do so in a manner that is convenient and pleasant for the client. As most business is repeat business, or comes from word-of-mouth referrals, social skills tend to be more important than technical skills. A digital image sitting on a computer, no matter how good, won't sell itself, but good marketing can sell a mediocre image. The professional, who may struggle to support himself by working long hours, needs to work quickly and efficiently, and needs tools that are reliable. One way that the professional speeds along his work is by using standard light setups, camera settings, and having a “house style”; these may not be optimal, but they work most of time, and most importantly, they lead to consistency. The professional simply does not have the time to fiddle with his equipment or processing as does the amateur.

The Artist

Neither of the above definitions directly brings up the idea of image quality, since all we can be sure of is that the amateur loves photography, and the professional sells photography, and I've seen good and bad photos from amateurs and professionals. Instead, let us introduce a third kind of photographer, the photographic artist, who can be relied on to consistently deliver high quality photographs.

With some innate talent perhaps, and by an understanding of theory and lots of practice — and maybe inspiration — the artist has internalized the art and has made it a part of himself. To the artist, making something good is a joy to himself and he greatly fears making junk. When you observe an artist making art, it appears to be effortless on his part, for the artist makes good art as a matter of habit. The artist intimately knows how his gear works: the camera almost seems to be an extension of his body.

But note that the artist may not be pleasant to work with, may be demanding, may not charge reasonable prices for his art, may not show up at the shooting location on time, and might be grouchy and irritable during the shoot. The artist may be a terrible businessman, but he cares far less about the business relationship than about the quality of the final product. He might show up on location, spend at most a few minutes doing his work, and then abruptly leave to everyone's astonishment, or he might put the crew through hours of misery because he expects perfection, but in either case the final product will be outstanding.

Unlike the professional, for whom time is money, the artist may spend an extensive amount of time analyzing the scene, taking measurements, and setting things up carefully — or not. Unlike the amateur, the artist knows how his gear works and what it can deliver under a wide variety of conditions, and so there is very little guesswork or trial-and-error involved. The artist might be highly concerned about his equipment, like the amateur, but will not be devoured by it like the amateur, knowing very well that “all that glisters is not gold.” He likely will make the best of whatever equipment he has at hand.

By analogy, we could say that the artist is not like an awkward young lover, but rather more like an old happily married man who loves his spouse but does not obsess over her, and rather sees her as the better half of himself. The fruit of this union is quality works of art.

One More

I ought to add dilettante to this list, someone who pursues a subject out of curiosity, or for being a well-rounded individual, or even to socially project the appearance of being an expert. A dilettante doesn't do photography for the love of the art, nor to make money doing it, nor for the purpose of making excellent final photographs, but for some other satisfaction. Being a dilettante can be perfectly harmless, or merely a half-hearted hobby. It can also slide into snobbery, which is highly undesirable.


As I mentioned earlier, these are more archetypes than they are stereotypes, more like models that distill the essence of human motivation, and so actual human beings are likely to be a mixture of these, or slide from one to the other over time. An amateur may eventually become an artist — and very many artists started out first as lovers of the art.

A professional might start out as an amateur and may be an artist, but also consider that many people choose professions due to social pressure, or family, or because they appear to be a desirable career, having nothing to do with art or the love of an art. If the professional takes time out from business to really work on their photography, they too may become an artist. Or perhaps, if an artist takes time out from his work to develop business skills, he too might become a decent professional.

I am sure there are many photographers out there who combine the best of all three: they have a love of the art, they are good at business, and they produce exceptional photographs as a matter of course. That is a good target to aim for!