Monday, March 06, 2006

Use the Golden Ratio

Rather than having one omnibus post about composition, let's break it down into reasonable pieces. I wrote a fast version once and Blogger ate it. It's "best" because the first post assumed much for such a complex issue.

Today, we'll start with photography's most basic compositional formula, and we'll later build from here.

What is the golden ratio?
The golden ratio is a mathematical equation determined by ancient Greek scholars to explain natural ratios. The ratio uses the irrational number 1.61803 to 1. It's still used in Western culture to create pleasing art ratios.

In common practice, the ratio is roughly 2 to 3. It applies both vertically and horizontally. It determines the heighth and width of most classically-cropped images.

This ratio also happens to be the same approximate ratio as most film formats. Consequently, as most images are made, they conform to the golden ratio. This also explains why 8 by 10 prints are not as faithful to the negatives as 8 by 12 prints are.

The golden ratio is also called the divine proportion, golden mean, golden number, golden proportion and golden section. This can get confusing when we talk more about the rule of thirds and power points because older PJs may call these intersections the golden mean points. Let's hang with the term "golden ratio" while we talk about the image edges.

What do we do with it?
If an image is well composed and full frame, there's no need to worry about the golden ratio. It's automatic.

If crops are needed, it's wise to consider the golden ratio. However, most crops should be obvious and the images should dictate the crop. We'll talk more about this soon.

With this said, we still need to use the golden ratio when cropping "plain" shots such as mug shots and the like. We want to use this ratio because it also fits layouts best. Publications are also based on the golden ratio. Magazines, newspapers, flyers, photographic prints and many computer monitors conform to this ratio because it's universal to all graphic arts.

When images conform to the ratio, they create a pleasing flow within the larger publication. Designers can easily insert an image with this ratio either vertically or horizontally into the layout. Additionally, the image gets more cumulative space by conforming to this ratio.

Frequently, square format images get the most space in publications with text. However, this is also a result of modular design and designers using the golden ratio for the entire text/art package area.

At this point, let's simply say images with severe horizontal or vertical crops don't get the space they often deserve. It comes back to the golden ratio and how ingrained this ratio is in Western culture.

Again, don't get glued to the ratio. When there is doubt, use the ratio. It's most often the correct answer.

In this example, four images are cropped loosely to the golden ratio while one is not. It should be easy to spot the different image.

How to easel crop to the ratio
On an easel, it's simple math. Divide the longest side by three. Multiply the result by two and you have the other dimension.
L / 3 = X
X * 2 = S

L = Long side
S = Short side
X = multiplication factor

For an exact number, divide the long side by 1.61803 or multiply the short side by this same number.

To make sense of this, here's an example. A hypothetical horizontal image must have an exact width of 5.25 to fit within an odd-shaped frame. To make the image we're printing conform to the rough golden ratio, let's do the math:

5.25 / 3 = 1.75
1.75 * 2 = 3.5

5.25 / 1.61803 = 3.244686439682824175077099930162
3.244686439682824175077099930162 * 1.61803 = 5.25

For an image to meet the rough golden ratio with a known limitation of 5.25 upon the longer side, the shorter side would be 3.5. The exact measurement is closer to 3.25.

Note we didn't say inches, feet or yards. It could be miles and still conform to the golden ratio. It's a pleasing ratio at any size.

How to Photoshop crop to the ratio
For once, Photoshop is actually easier than the old way. Choose the Crop tool. Set the long side to 3 (either the height or width) and the other side to 2. If resolution has any number, delete it. Moving from the upper left corner to the lower right corner, click and drag the mouse to make a crop box.

Once the crop box is made to fit within the image area, click and hold anywhere within the crop area to move the box until the crop is in the best location (we'll eventually discus edge inevitability). Once the crop box is located in a pleasing location, double click inside the crop box to set the crop. It's now set to the rough golden ratio.

If a specific image resolution is required after the crop, do the following: Image, Image Size, uncheck Resample Image (it defaults to Constrain Proportions), type in the required resolution, hit OK and it's done. Save.

Enough for now,


shutterjockey said...

Due to layout and design, i couldn't count how many times I was asked to flip a negative so the subject was looking in the opposite direction. Here comes the editor with my proof sheet, here we go... It is true that 8X10 print is not faithful to the negative but there is not a JP that I know that would print 8X12. That requires going to 11X14 paper and, hey lets face it, we're cheap. Ever see a PJ buy a round? I'd be ducking from the lightening.

Mark M. Hancock said...

While it happens at magazines and in ads, deliberately flopping a negative is a firing offense at most newspapers.
I won't do it. There has already been a successful lawsuit over a flopped negative. It visually turns a suit cut from male to a female. The flop cost that company several thousand dollars and some of their reputation.
It's better to work the scene harder and get images from both sides of the subject if the layout desk is too trapped in their layout rut.