Painters often create what they call a hierarchy of edges. Bright important edges are usually sharp, but darker, less important edges become lost edges.

This effect is easy enough to simulate in Photoshop, but I wonder how common it is. Most people use selective, luminance-based lens blur to simulate shallow depth of field. I'm talking about guiding the eye more in the painterly, less optics-based sense. This post is mainly about analyzing what painters do and incorporating those ideas into photography, although it is also interesting to see the efforts of artists who are approaching photographic ideas from the painterly side.

One could argue, I suppose, that creating a hierarchy of edges is only necessary for painters, and that photographers needn't worry about this issue (aside from DOF) because most of the edges are produced by the camera already suitably hard or soft. I'm not so sure about that. I think further manipulation might be warranted and beneficial.

UPDATE 3/8/2010

MM Forum Discussion

You never see a flat rollercoaster track go into a perfectly circular loop-the-loop because while that track is continuous in the first derivative, it is not continuous in the second derivative, and would make for a very jarring ride.

Entering the circular loop from a horizontal track would imply an instant onset of the maximum g-force (as would a direct transition a circular path with smaller radius of curvature). An immediate transition from one radius of curvature to another would give a continuous, smooth track, but with discontinuous second derivatives. Clearly, a function with continuous higher derivatives would be preferable.
Roller Coaster Loop Shapes

So is there a special curve with which to make the optimal photo studio wall?

This is why car surface designers, who are in many ways reflection pattern designers, worry about continuity and smoothness in the higher derivatives.

- A Periodic Table of Form: The secret language of surface and meaning in product design by Gray Holland

The fifth image in my Nothing is Real but the Girl series.

Hokusai's Great Wave off Kanagawa is so iconic that I think it works well magnified and made somewhat more abstract - somewhat similar to the way Landor Associates handled the corporate ID program and signage for General Electric. Large and cropped.

I picked up a fun book on the internet on Fifties pinup and cheesecake photography called Best Photography Trend Book 157. It was sold as being full of original model signatures. That wasn't the reason I bought it, but it was a fun plus.

When the book arrived I carefully leafed through it. Sure enough, there were the signatures, as promised: Sandra Edwards, Vivian Melody, Mona Miller, Marilyn Hannold, Jody Nelson, Virginia de Lee, Arlen Hunter, Betty Brosmer, Mishe Swanson, Donna Fisher, Jackie Hilton, Diane Weber, Marilyn Masters, and four others. Turns out one of the 'four others' was Marilyn Munroe. Wow! Hey, wait a second, that's not Marilyn Munroe's signature. Come to think of it, all the other signatures are in the same pen, and in the same handwriting.

Those aren't unique signatures. Looks like somebody - not sure who or when - made some notes in the book. Oh, well. Not so bad. Like I said, I bought it for the content.