Monthly Archives: August 2007

Retinas are different but see the same thing

Here’s your color and vision article for the week from Dr. Color’s assistant (via the good people over at LiveScience.com).

The first images ever made of retinas in living people reveal surprising variation from one person to the next. Yet somehow our perceptions don’t vary as might be expected.

Imaging thousands of cells responsible for detecting color in the deepest layer of the eye, scientists found that our eyes are wired differently. Yet we all — with the exception of the color blind — identify colors similarly.

The results suggest that the brain plays an even more significant role than thought in deciding what we see.

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Something old, Something new, Something a little less blue

Eleven days after my webhost (DigitalSpace.Net) “upgraded” their servers and broke my website quite brutally, I once again have the ability to edit these pages. It only took seven phone calls and e-mails to their tech support to get a resolution. I ended up doing the debugging and finding the resolution on my own and then had to wait for someone else to do the work that I couldn’t do myself.

As someone who did more than two years of web site and software support, I found this experience extremely frustrating. The slowness indicates that the staff is overworked, has poor task tracking tools, lacks motivation, or worse. I don’t want to say too much about that, except to mention that one of the support people I talked to on the phone was thoroughly unsympathetic when I complained that they broke my site and didn’t describe what they were going to do. And one completely dismissed my suggestion that they could have communicated information about the transition better.

Two results: I’m switching from MovableType to WordPress for better stability, and I’m considering different web hosts. Let me know if you have suggestions on the latter.

I think I’m going to like WordPress, but transitioning a weblog from one content management system to another is never without hiccups — which is why I’m finally posting a week after getting my website back. Expect some more changes in the coming weeks.

Posted in General, Life Lessons | Leave a comment

Ask Dr. Color’s Assistant: Saturation

Dear Dr. Color:

For the last few decades photographers have been infatuated with saturation. I suspect that if prints were compared with the original views that they would be more saturated than reality. It certainly does ‘punch up’ the picture though.

What is saturation, though? How about the term “vibrance” that Adobe is throwing around?

Believe it or not, there are actually ISO standard technical definitions of most color terms. Here’s a definition from the CIE’s “International Lighting Vocabulary” (1987). Saturation is “colorfulness of an area judged in proportion to its brightness. Note: For given viewing conditions and at luminance levels within the range of photopic vision, a color stimulus of a given chromaticity exhibits approximately constant saturation for all luminance levels, except when the brightness is very high.” Colorfulness is a perceptual attribute of how chromatic something is.

So you can decouple chroma (more or less the same as hue) from luminance and saturation. The farther you get away from neutral for a given hue, the greater the saturation. Essentially, if something seems very colorful (now matter how bright it appears) it’s more saturated. So you pretty much have that right. But it’s not exactly the same as color purity in a spectral sense, because many colors (like the purples) can be quite saturated but are always a combination of other colors.

It’s true that in RGB space, when you want to saturate colors you have to move R, G, and B away from neutral, which can have undesirable consequences for other colors. Different color systems are much better at these color transformations, in particular HSV (or HSL) and L*a*b*. I’m a big fan of L*a*b* for saturation manipulation because it’s completely decoupled from luminance/brightness, and it’s easy to perform via scalar multiplication for all colors at once; there’s no need for curves and no impact on overall color-balance as long as a* and b* are multiplied by the same amount.

As far as I can tell, “vibrance” is a completely nontechnical term. In Adobe products it “is a more selective version of the Saturation slider. Whereas the Saturation slider increases the saturation of all of the tones in your image, the Vibrance slider limits its saturation boost to primary colors, leaving skin tones and other secondary shades untouched.” Sounds like an adjustment in L*a*b* space that is greatest along the a* and b* axes.

Posted in Color and Vision, Photography | Leave a comment

Ask Dr. Color’s Assistant: Determining Monitor Luminance

Dear Dr. Color:

I wish to measure the brightness of my LCD monitor so that I can set it to the recommended brightness for photo editing work. How can I convert the measurements from a hand held exposure meter to candles per square meter or NITS?

First, you must be using a spot meter; incident lightmeters won’t work for this task. (I suppose you could use an incident meter in a room with no other illumination…) Then compute the exposure value using your light meter, which shouldn’t be too hard: just collect f-stop, shutter time, and ISO setting. That’s easy. The tricky part is to determine the meter’s calibration constant. According to Wikipedia, it’s probably 12.5 (for Canon, Nikon, and Sekonic) or 14 (for Minolta and Pentax). Take all of those numbers and put them into this equation:

((calibration constant) * (f-number)^2) / ((time) * (ISO speed))

The resulting value is luminance in candelas per square meter. There’s your radiometry lesson of the day.

But I wonder, doesn’t your monitor calibration tool perform this as one of the first steps? Mine, the consumer-level Monaco EZ-Color suite, does. And if you’re that worried about brightness, you’ll probably need to worry about other aspects of the ISO standard: surround illumination, specular highlights, etc. Those other factors determine apparent brightness and color values, which is probably what you’re worried about. And isn’t Photoshop’s soft-proofing good enough?

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Kaun Banega Crorepati? Or “Why you need $87,000,000 to be rich”

The name of this post — “Kaun Banega Crorepati?” — is the title of the Hindi version of “Who wants to be a millionaire?” A crorepati is someone with 10 million rupees, or about $250,000 US. One crore is 10 million of anything, preferably rupees. It’s also 100 lakhs. (So, one lakh is 100,000.) This system of lakh and crore is still very widely used in India for describing large numbers, and commas separate crores, lakhs, and everything else. For example, the U.S. debt today is $895010,53,12874.54. Of course, for a number that big you need to start talking about even larger denominations: the arawb and kharawb which are 100 crore and 100 arawb respectively.

Anyway, that’s a roundabout way of introducing an article published in today’s New York Times: In Silicon Valley, Millionaires Who Don’t Feel Rich. As with the previous article in the series Age of Riches, this article is about the new-money class.

Lisa didn’t have much sympathy for Hal Steger, the 51 year-old marketing executive who’s worth $3.5 million and said, “A few million doesn’t go as far as it used to.”

But I totally understand. A few years ago, a friend and I figured out how much you need to have in the bank to be rich. Not just “rich.” That’s easy. We meant “filthy, never-work-a-day-in-your-life-again rich.” My friends, to be rich you need $87 million.

I can’t remember all the details, but think about it. First there’s housing. You’ll need a decent house in Weston or Lincoln, Mass., the kind that’s so large your neighbors want to get it rezoned because you have fundraisers there so often. That’s easily $10 million (or about $650K per year for the mortgage) plus annual taxes of about $300K. And cars. Add in the cost of buying/leasing a new car a year and you’re easily past a million in necessities. And don’t forget food.

Then there’s the question of what you’re going to do if you don’t do “real work.” As far as we could tell you only have three options: travel, buy stuff, and give away money.

Travel: You need enough to buy two or three first class tickets and deluxe accomodations everyday. There’s $5K/day, or $1.8 million/year.

Buy stuff: I don’t shop a lot, though I could easily get into art collecting. Art prices are going up, up, up. Let’s say $1 million/year. Plus another $1K/day for sundries. That’s about $1.4 million.

Charity: Because we’re generous people, we figured we’d give as much aways as we spent on ourselves. So that’s $4.2 million plus food. . . .Carry the one . . . $4.3 million for charity.

Since we’re not working, we need to live on interest. In the worst years, people with money can get a 7% rate of return. Let’s see “X x 0.07 = $8.5 million,” so X = $121 million.

Oops! Inflation. Hal Steger was right: A single person needs $121 million (or 485,71,00000 Rupees) before they’re rich.

Posted in This is who we are | Leave a comment

Two Cemeteries in Dighton

Today I finally got out and photographed a bit. How do I pick where to go? Usually I look somewhere west of me (about 1/2 of the Commonwealth) because I’m on a suburban/rural swing right now. I’ve been thinking, though, that I might be missing out when I just jump onto the turnpike.

So last night I got out my Metro Boston atlas — which includes 167 of the 351 cities and towns and roughly 4.3 million people — closed my eyes, flipped through the pages, and stopped at Dighton. I had never heard of this small town, known as Taunton’s “Southern Purchase” when it was founded in the 1690s. Nor was I aware of Norton, a northern neighbor of Taunton and another place I photographed today.

There are many, many cemeteries in Dighton, far more than one would expect for a town of 5,000 people. I visited two: Hathaway Cemetery and Dighton Cemetery, perhaps the oldest in town. Here are some highlights.

Hathaway Cemetery

Submit, Wife of Isaac Babbit
1799-1877

Victory and through victory Life

  • Ardelia Hathaway (♀ – 1843-1921)
  • Roxcy Hathaway (♀ – †1833 Æ26)
  • Mercy Austin (♀ – 1821-1880)
  • Almedia Wheeler (♀ – †1886 Æ53)
  • Anjenette Pettis (♀ – †1898 Æ81)
  • Benjamin P. Jones (♂ – †Jan.? 9, 1864 Æ49, Died at Bermuda Hundred, Virginia) [1]
  • Adeline Woodward (♀ – †1864 Æ24)
  • Gideon Walker (♂ – 1838-1907)
  • M.J.H. (†1870), L.B.H (†1908), R.P.H (†1918), G.L.H. (†1958), B.M.H. (†1949)

Dighton Cemetery

In Memory of Mrs. Elizabeth Richmond, the Worthy Consort of Silvester Richmond Esq. who paid the Debt of Nature June the 23d Annodomini 1772 in the 65th year of her Age.

Sincerely lamented by her disconsolate Partner & Children

  • Thomas King (♂ – †1713 Æ70)
  • John Reed (♂ – †1720/21 Æ2 yrs)
  • Mr. Matthew Briggs, “who died of the smallpox” (†1703 Æ58)
  • J. Emmons Briggs, M.D. (♂ – †1867 in Burlington, Iowa, Æ25)
  • Patience Ann Briggs (♀ – †1832 Æ15)
  • Mercy Briggs (♀ – †1783 Æ30)
  • Huldah Horton (♀ – †1884 Æ81)
  • Nathaniel Bower (♂ – †1728 “Æ3 yrs & 3 mo. wanting 5 days”)
  • Elizabeth Bowers (♀ – †1748 “Æ3 yrs & 9 mo. wanting 5 days”)
  • Abigail Bowers (♀ – †1748 Æ30)
  • Bathsheba Baylies (♀ – 1745-1822)
  • Lusannah Turner (♀ – †1844 Æ31)

[1] – It’s likely that the date was actually May 9, 1864, not January 9, 1864.

Posted in Burying Grounds, Commonwealth Project | Leave a comment

Photobook Club

I’m just throwing this proposal out there and hoping someone has an idea or two of how to achieve my goal. So please reply.

I like photobooks. Monographs, surveys, collections, criticism . . . it doesn’t matter.

I like reading and discussing books. The latter usually happens with Lisa and our friends via book club. But photobooks aren’t really what they’re into. (I can understand.)

Books of photography can be pretty expensive, and I try to respect copyrights. So scanning large portions of books just to discuss them isn’t something I would really do. Aggregating from the Internet is possibly a different matter.

Any suggestions about how to start (and sustain) a photobook club? Either virtual or in-person.

Posted in Book Notes, General, OPP, Photography | Leave a comment