john bishop images | photography | vancouver, bc

workshop session 1 – foundation

  Adobe, colour space, dynamic range, Lightroom, perception, Photo ME, Picasa, Reveal, sourceforge

the first session in the Introduction To Digital Photography workhop was held last Wednesday, January 13.  after introducing ourselves and our cameras we shared our expectations and i presented a proposed workshop outline.

the goals of session one were

1. to introduce the software that will be used in the rest of the workshop, and
2. to understand the limitations of technology, and
3. to understand image size and quality.

there is a broad range of people attending, from those comfortable with technology to those not so at ease, with equipment ranging from midrange point-and-shoot digital cameras to more top end Pentax and Nikon DigitalSLR gear.  when we talked about what people hoped to get from the workshop, almost everyone one wanted to get off automatic or green mode;  i couldn’t have asked for a better fit to what i hoped this workshop might be about!

i wanted top make sure that software used in the workshop was free and would run under both Windows XP and MAC OS.

• an image editing program that was quick and offered some basic functionality (crop, grayscale, contrast, sepia toning, exposure, fill light, etc.).  Google’s Picasa to the rescue.  it is platform independent, very quick and offers all the editing capabilities we need at this level.
• a program that would expose the EXIF meta-data stored in JPEG and RAW image files.  my initial suggestion was Photo ME, but that only runs on Windows systems.  after introductions, i knew i had to find, at worse, a MAC OS program, and, at best, a program that was platform independent.  Reveal from Album Shaper on sourceforge.net seems to offer the best function at no cost and runs on both Windows and MAC OS systems.

as a quick aside, sourceforge.net is one of the best places on the ‘net to get good quality open source software, usually at no cost.  this post has more info on open source and open licensing.

if you’re following along at home, download Google Picasa (Version 3.6) and Reveal (Version 1.2) and install them on your system … we’ll get into more of the meat on these programs when we talk about post-processing and digital developing, but for now download it and try them out.

i also introduced Adobe’s Photoshop Lightroom, by far the best digital-developing and digital asset management tool.  it runs on Windows XP and MAC OS and at $300US, it may not break the bank for some.  note that Adobe is currently working on Version 3 and the product is in beta testing.  you can download the beta here.

one of the greatest puzzles for people new to digital photography is how the printed version of a picture can look so very different from what you thought you captured when you pressed the shutter, or from what is displayed on your computer’s monitor.  enter the realm of man’s amazing sensory systems and machine’s truly amazing limitations at mimicking them!  if we don’t understand technologies limitations we are bound to be frustrated and disappointed either in our equipment or what we might perceive as our lack of ability.  a good photographer is someone who understands those limitations and works with them and is able to use them to creatively express a vision … read on.

dynamic range

the human visual system is able to perceive an incredibly wide range of brightness levels.  from the darkest moonless night to the brightest sunlit mountain side covered with fresh snow, we can differentiate 1,000,000,000 (that’s one billion) different levels of brightness!  technology on the other hand is exceedingly limited.

• modern cameras are capable of detecting 10,000 different levels of brightness, 1/100,000 lower
• LCD monitors and modern HDTV offer 1,000 different levels of brightness, often referred to as contrast levels
• paper on the other hand allows only 100 brightness levels, 10,000,000 time fewer

this chart may help you understand the significance in these differences.  remember that each step up the left hand scale is ten times larger (a magnitude); a logarithmic scale as opposed to an arithmetic scale.

obviously something has to suffer.  what is lost are the gentle variations in hue and subtle gradings of tone that the human eye can sense.  it’s no wonder that the printed image falls far short of our vision, both perceived and expected.  but when we look at the genius of Ansel Adams and come to understand that he worked with only 12 brightness levels, we begin to see how this limitation can be a huge force for creativity.

colour space

just as our eyes can perceive more brightness levels than our cameras, they can also perceive about 10 million different colors.  when combined with dynamic range limitations, a means of mapping the limitations to the human visual system is needed – welcome to colour spaces!

according to Steve’s DIGICAMS, a “color space” is a language that describes what the red, green, and blue values in your images really mean.  different equipment use different shades of red, green, and blue as the primaries which means that a particular RGB value can indicate an entirely different color on two different devices … or images.  tweaking the red, green, and blue primaries gives the ability to store images in a color space that better matches the equipment that will reproduce the photos later.

for our purposes, we consider two colour spaces.

1. sRGB
   the sRGB colour space was defined in 1996 by HP and Microsoft and is what most PC’s and monitors use.  the sRGB colour space is rather small covering only about 35% of the human colour range. it is the defacto standard for most of todays electronic gear, including digital cameras and HDTVs as well as most image editing software.
2. Adobe RGB
   the Adobe RGB colour space was defined in 1998 and covers almost 50% of the human colour range.  it will reproduce vibrant, saturated colors like deep yellows, cyans, and magenta colors found in subjects like flowers, some clothing dyes, and other subjects with very deep and saturated color. Adobe RGB is available on newer prosumer digital SLR cameras and is supported by high end software like Adobe’s Photoshop.

and like dynamic range, paper has a significantly reduced ability to reproduce the full human range of colours, again most limited at the saturated end of the colour triangle, as shown below.

although the ProPhoto colour space, available on top-end professional or broadcast quality equipment costing tens of thousands of dollars come close the the human range, it is still limited.

summary

technology is a long way from accurately capturing and reproducing the human experience; photography is very much an art, not a science.

photography is often about making compromises, informed by an understanding of technologies limitations.

it is in those limitations and compromises that we find the creative room to express our vision.

with a better understanding of the underlying technology, this sessions assignment is designed to take that understanding one step further … JPEG image sizes and image quality, with a nod to camera RAW formats.

… assignment 1