Wednesday, February 24, 2010

Another Snowy Morning

We woke up to a snowy morning, with snow sticking to the trees so I set out looking for photo opportunities. One of my first discoveries was this tree which still has some of last year's leaves. It was warming rapidly and the snow was already falling off the trees by the time I reached the Southville bridge from which I shot several photos of the river below. Several of the images, including this one, resemble satellite photos of the Earth from space.
The water has risen over much of the ice and only a few small patches of snow are above water. Like most of the rivers around here the water is brown from tannin which comes from leaves and other vegetation  falling into the water and decomposing.

Tuesday, February 23, 2010

Open Letter to the Media

This morning on the radio I heard a news story saying that Rick Lazio is now ahead of Gov. Patterson in the latest polls. Already we are into reporting the “horse race” rather than information that is useful to deciding whom we want to vote for. Please, rather than grabbing the latest poll as a headline story, do a bit of digging. Interview the candidates and report on their positions, their solutions to problems that face society. Press them for real proposals not just broad stroke party ideology. Report on their speeches and make note if they change their message for different audiences. When there is an opportunity to directly question candidates, confront them on anything vague or inconsistent. Lastly tell us who is funding their campaign. Please be journalists, not just conduits for political spin.

Sunday, February 21, 2010

The Only Flower I could Find

Okay, I'm there. Back in January I said I was enjoying winter but maybe by February that would change. Today I found myself longing to photograph something that wasn't white, covered in snow and ice. Maybe it was battling a head cold since last Thursday or maybe it was just that winter is getting old. I'll probably have a few more enjoyable winter days but if spring decided to arrive tomorrow (not likely) my heart would not be broken. Unfortunately my snow blower is broken so I have to play mechanic out in the cold tomorrow. To say I am a reluctant mechanic would be an understatement.

The photo is my wife's calender challenged Christmas Cactus. It is beginning a blooming cycle with just this one flower. In a few days the Clivia will be bloomed and I'll have more options if I have the urge to photograph flowers again.

Thursday, February 18, 2010

Right Idea, Wrong Reason

I've decided to throw in a technical/instructional post occasionally. This is the first. I thought of doing one every week or two but I don't want to tie myself to a schedule so they will be random when I feel inspired to expound on some topic.

Several times in recent years I have encountered a theory of digital exposure that I could never quite comprehend, a philosophy of “exposing to the right”. According to this theory, in an image spanning several f/stops fully half of all the data (1024 bits on this chart) in a digital image resides in the brightest f/stop, half of the remaining data in the next lowest f/stop and so on until you reach the lowest f/stop which (according to the theory) contains only 8 bits of data. The theory holds that by exposing to the right you capture more of the available data. They place a scale at the bottom of a histogram similar to this one to illustrate the idea.
 I suspect that the idea derives from the f/stop representing double or half its adjacent setting and in terms of brightness levels it is absolutely correct that brightness of an image declines geometrically as the f/stop is decreased. In the Zone System, Zone 10 is twice as bright as Zone 9 and so on. It is a fallacy however to equate digital data to brightness.  If you were to shoot two uncompressed images, one exposed toward the left of the histogram and another toward the right, the two files would contain exactly the same amount of data. It would simply be distributed differently in the histogram. If you expose so that no pixels fell in the brightest segment of the histogram shown above you are not “losing half the data”. As long as the curve drops to the base line on both sides of the histogram (as it does in the illustration above) you have lost nothing. You lose data only if the curve ends on a side rather than the baseline (RAW is somewhat of an exception but that is another discussion).

What the histogram represents is the distribution of pixels at each of the 256 available levels of brightness and each pixel consists of exactly the same number of data bits as every other pixel, 8 bits per channel or 16 bits per channel, no more, no less. In an 8 bit image the data to describe the pixels at “0” (pure black),  255 (pure white) and every pixel in between, each contain 8 bits of red  data, 8 bits of green data and 8 bits of blue data for a total of 24 bits. Likewise each pixel of a 16 bit image contains 16 bits per channel for a total of 48 bits per pixel. In practice cameras today use only 12 or 14 bits of the available 16 in a 16 bit image but the file is still written in 16 bit format. No pixel is written with 1024 bits. The only pixels that are described by 8 bits are those in an 8 bit single channel black & white image and then all pixels consist of 8 bits regardless of where they fall on the histogram.

So why all the fuss about “exposing to the right” if there isn't more data there? Because digital photographers have discovered that if you stretch the tones of the shadow areas toward the right to “open them up” you often get confetti colored “noise” but if you darken bright pixels in the highlights you don’t appear to get noise. The “half the data is in the brightest f/stop theory” is an attempt to explain that phenomenon but as the above shows it has nothing to do with the amount of data. So why is it true that opening up shadows produces noise but darkening highlights to retrieve detail does not? It is a matter of perception.

We’ve all seen noisy shadow areas so I won’t trouble myself to demonstrate that but we should look at the other end of the brightness scale as a way of understanding what is really going on when we “expose to the right”. I'll start with this snow scene photo.
It looks nearly monochromatic but I took a sample from the bright snow, the dotted rectangle near the center, and enlarged it 600% to see what colors were present. It still looks mostly monochromatic but when I increase the saturation 100% it is suddenly apparent that there is a lot of color noise. It just isn’t evident because the saturation is so low.
The real reason that shadow areas develop noticeable noise and highlights do not, is a matter of saturation. Both have noise because digital sensors don’t see color. They only see tones of grey through red, green and blue color filters placed over each photosite on the sensor. The software then generates a color for each pixel by comparing the amount of light reaching each photosite relative to its neighbors in a Bayer array. The exception to this is the Foveon system which uses a separate sensor for each channel.

The visual difference between color noise in highlights and in shadows is due to saturation. It has long been a practice of film photographers to deliberately underexpose by a half stop in order to increase saturation.  Shadows show noise more than highlights for exactly the same reason. Saturation increases as you go left on the histogram and decreases toward the right but color is most clearly distinguishable in the middle.

Even to our eyes, colors are most easily distinguished from one another in average light. In dim light colors become murky and in really bright light they wash out. If I were to take you into a dimly lit room and ask you what color the arm chair in a particularly dark corner was, you would have difficulty accurately describing the color. If I did that with a group of people I would probably get different opinions from each person. Those discrepancies would be “noise”.

Digital sensors are no different and, in their attempt to distinguish color, individual pixels generate variances in color (noise) as the color becomes harder to distinguish. When you brighten the shadows of a digital image you are asking the computer to do the same thing I asked of you in the darkened room, to describe a color that there was too little light to accurately see and in brightening it the discrepancies become more apparent. Likewise if I asked you to tell me the color of something the sunlight was glaring off from. You (or the camera) can’t accurately determine color under those conditions but since the saturation at the bright end is so much less, the noise in highlights is not as apparent.

So should you expose to the right of the histogram? In the user manuals most or all camera manufacturers recommend centering the histogram. If you then darken the shadows and brighten the highlights you are starting with clear color and darkening it or fading it out. Neither will create objectionable noise. If you darken 40% tones to 25 or 30% you are working from more clearly seen color toward less clearly distinguishable color. The same is true if you brighten 70% tones to 80-90%. If you do the reverse, stretch the shadows or highlights toward the center, you are forcing pixels of less discrete hue to be more discrete and that is when the discrepancies show up.

Arguably you might get cleaner whites by exposing so that the histogram is as far right as possible. Also if you expose to the right your darkest tones start out closer to the center, the shadows will have less noise because the sensor was able to “see” the real color more accurately with the increased exposure. Because desaturated (highlight) noise is less evident than more saturated (shadow) noise, biasing the exposure toward the highlights will produce smoother results than biasing toward the shadows but not because there are more bits of data on the right. It is a simple matter of saturation.

As a final note, if the light range is such that you will inevitably lose either highlight or shadows it is better to lose the shadows. The reason for this is that we are comfortable with not being able to see into deep shadows but glaring highlights either cause our eyes to adjust to the brightness or to look away to avoid the discomfort. Because of this, small washed out highlights in an image are okay but large areas of blank white tend to look unnatural.

Tuesday, February 16, 2010

Square Format Digital

Several years ago I sent correspondence to both Olympus and Canon asking why they didn't consider making a digital camera with a square sensor. Olympus replied politely saying my suggestion had been forwarded to their engineers. Canon ignored me.

Why square? Because you can shoot a horizontal or a vertical without turning the camera. All you need are some guidelines lightly inscribed in the viewfinder or on the back screen to compose and crop after shooting. Or you could even shoot square photos, something Hasselblad, Rollieflex and others did for years. With digital you could even use software to crop in the camera as the image was being recorded. One of the most loved cult cameras of all time was the Mamiya 6 that shot 6x6cm images on 120 film. If they were to create a digital version it would probably be an instant hit.

Well, none of the above saw fit to try but Panasonic has done it, sort of, and I can't claim any credit because I didn't write to them. I say sort of because they get the square image by cropping a rectangle, not the other way around. Their Lumix GF-1 has several aspect ratio options selectable in camera  three of which are square, 8.9MP, 4.4MP and 2.2MP respectively. I'd rather they had made the sensor 4000x4000 pixels instead of the 4000x3000 pixel sensor they used but it is an interesting concept. It is designed as part of what is known as the four thirds standard. Cameras adhering to the standard can exchange lenses across brands and apparently many older high quality lenses can be adapted to the four thirds bodies which (so far) are only being made by Panasonic and Olympus (which doesn't have the square format option). They are pretty pricey though with the Panasonic GF-1 body selling around $900 ($1200 with a lens).

I cropped the above square photo from a Canon G10 image. It is a 10.9MP square image. I bought the camera for $410 with a lens. I think I'll stick with cropping in the computer afterward.

Sunday, February 14, 2010

Change in Layout

Last night after posting the comments about what constitutes art I removed a widget that automatically fed a new art quote whenever someone visited the blog. I did so because I noticed that it was tacking on advertising, "monetizing" my blog, something I have so far resisted doing myself and I sort of resented the back door use of my blog to create profit for others. Granted they were providing a service but I can live without it and with minimal effort I can provide my own art quotes at the end of each post. I just may do that.

"Sometimes I do get to places just when God's ready to have somebody click the shutter." 
Ansel Adams

Saturday, February 13, 2010

What Is "Art"?

Michael Johnson on The On-line Photographer has been grappling with the conundrum of what makes a photograph art as opposed to just craft. I've been pondering the difference for years and dealt with it rather snarkily (a coined word?) in a post back in August of 2008. I periodically get caught up in an effort to define art only (like the Aug. 2008 post) to give up in disgust because the term is used so loosely that the word has no fixed meaning. It does however have strong personal importance to people who take their creative work seriously as a measure of their achievement and they (we) occasionally agonize over whether what we are doing really 'measures up' to the level of art as opposed to 'mere craft'.

There are of course people who don't agonize over it. Andy Warhol is quoted as saying "art is what we can get away with". There are also those who contend that if an artist says it is art, it is. Think urinals and snow shovels or for that matter, pickled sharks. And then there are the art historians who designate things as art whose creators likely had no pretensions or even notions of Art. The photographs of E. J. Bellocq come to mind or for that matter many pre-modern painters, sculptors, and other creatives who produced their work before the contemporary notion of "artist" had even come into being. DaVinci in his letters to nobles when applying for work described a list of things he could do, the last of which was that he could paint pictures. The descriptive "artist" was nowhere on that list. Never the less today, we have art and artists and thus feel compelled to define what that means even if we cannot agree on what it means. Perhaps the best we can do is what Mike did on TOP and come up with a personal definition.

I begin by relaying what I attempt to do. The word attempt is important because I never fully succeed. I am a photographer and describe myself as what I call a visual omnivore. I have been advised by folks in the business of advising artists on how to advance their careers that I should stick to one subject matter but I can't do that. I look around at the world and see things that excite me visually and I feel compelled to photograph them in a way that allows me to share that excitement with others.  I am primarily a landscape photographer but I also photograph cars, buildings, anything in which the light reveals something special to me. I could say it is all about light but even that would not get to the heart of it.

I believe that everything in the universe is connected on a subtle level. There are moments in which the creative person senses connection with "the other" in a profound way that cannot be put into words and only with difficulty into a visual expression. Mike Johnson talks in his definition about genius and the notion that we all have genius. I think the difference between those we commonly refer to as being a genius and the rest of us is not just their ability to see or to comprehend things that are profound but to communicate their insights to the rest of us. To me art is communication of an experience of connection, a communion with the subject which goes beyond its objective existence, and the translation of that experience into a new object through which others may share the experience.

Unfortunately we artists cannot, certainly I cannot, create universally understood representations of those experiences we wish to share. Inevitably some, even most, of those who view the products of our efforts won't "get it". Therein lies the vagueness of the term art. For my own part I have resolved to pursue my objective without worrying whether what I do is "Art", concerning myself only with whether and how well it communicates and I endeavor to look at the work of others the same way. Does this photograph, painting, sculpture, whatever, speak to me? If it does, it has fulfilled its creator's intent no matter what we choose to call it and that is what matters.

Wednesday, February 10, 2010

The Family Gets Smaller Again

My eldest sister Virginia died yesterday at the age of 80. She and my eldest brother were both teenagers when I was born so they were 'adults' for as long as I can remember. As children we (my other brother and younger sister) played with their children. In the photo above she was about 20 years old. She was musically inclined and tried to teach me to play the piano when I was about 8 but I wasn't much interested and never did learn though I've always enjoyed hearing others play. In the background near the right edge of the photo you can see our dog Sambo. He was named after the main character in a children's book (Little Black Sambo) that I'm sure would be politically incorrect these days.

I confess that I never had the same relationship with Ginny that I had with my oldest brother Bruce. It's probably a gender thing. Bruce did all sorts of things that I admired, he was a fireman then a truckdriver. He waterskied, flew planes, and SCUBA dived. Ginny was a mother, like my mother, someone caring but not exciting to a young boy. As I got older the family moved different places and the miles between us added to the gender distance. I'm sure I didn't appreciate her as much as she deserved.