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Recently I’ve been experimenting with a technique for converting photos to line art, which can then be colorized. (I don’t claim this technique is original to me, but I’ve been refining it for my own purposes.)
The essence of the technique is the conversion to lines, using the color dodge and multiply blend modes. In the artwork above, I started from this photo:
Most photographic and print publication work involves operating within rectangular frames. The relationship of width to height is the aspect ratio, expressed as, for example, 1:1 for a square, 1:1.5 for a 6 x 9 book, or 1:2 for a sheet that is twice as wide as it is tall. Conventionally, the width is stated first: that 6 x 9 book is in portrait format, whereas a 9 x 6 book would be landscape, bound on the short side, and most inconvenient to read.
A special case is the golden section or golden ratio, a rectangle with the proportion 1:1.618 (between 3/5ths and 5/8ths). In this rectangle the smaller dimension is to the larger as the larger is to the sum. In other words, 1 is to 1.618 as 1.618 is to 2.618. And as 2.618 is to 4.236, and so on. This relationship, which can be extended indefinitely, was known since classical times, and it underlies the Fibonacci Series and the modular architecture of Le Corbusier, among other expressions. Gustav Theodor Fechner, a German scientist, studied people’s responses to rectangular shapes in 1876 and concluded that the golden section is the most pleasing, though his methodology and results have been questioned. But other aspect ratios also have historic and aesthetic associations.
Some photographs — like this one of “Inside Out,” 2006, by Ueno Masao (b. 1949; Kanto region: active in Kamogawa, Chiba Prefecture; madake bamboo, rattan, and gold leaf, Asian Art Museum, gift of Ueno Masao and Tai Gallery, 2006.41, photograph by Kaz Tsuruta) — set an object against a background that subtly blends from darker to lighter tones. (The photo appears in the book Masters of Bamboo.)
In page layout you might want to fit this vertical image into a more horizontal space without losing any of the image. For a long time I struggled with the best way to accomplish this in Photoshop.
I wish I could say I invented this technique for correcting color cast, but I actually learned about it from an online tutorial. Here I’ve added a wrinkle that is helpful for people like me who haven’t upgraded their Photoshop in a while.
We’ll start with this image of the multimedia center at the main branch of the San Francisco public library.
The first thing we need to do is to duplicate the image.
Here’s a Photoshop tutorial that “uses two adjustment layers to lower the vibrancy of the photo while preserving some colors.”
Well, fine, but why go to that trouble? All you need to do to achieve this effect is to duplicate the image, change it to grayscale with whatever technique you prefer, and then apply the image in whatever percentage gives the best result.
Here’s the before and after from the tutorial.
Here’s the result using my simpler technique. I just changed the mode on the duplicate to grayscale but of course there are other ways to desaturate, which might be better. I could have matched the above image exactly but I couldn’t stand how murky and low contrast the original image was, so I couldn’t resist fixing it using my usual Photoshop adjustments technique.
Why complicate matters?
While waiting for the Super Tuesday results to come into focus, let’s spend another day on Photoshop before shifting gears to another of our topics. The other day I talked about faking a tilt-shift effect, which basically involves blurring a gradient mask. Because I was blogging from home, where I don’t have a recent version of Photoshop, I used a Gaussian blur instead of a lens blur.
So what’s the difference? In theory, there’s a fundamental difference, which can clearly be seen in the following chart based on a Russell Brown presentation reported on Computer Darkroom.
You can see that Gaussian blur, in the middle column, erodes edges and grays white areas, while lens blur, in the right column, applies a geometric (somewhat hexagonal) effect similar to that of a camera lens without dulling highlights.
In the real world, however, the results may not be as noticeable. Here is an image with a Gaussian blur (top) and a lens blur (bottom). Because they use different metrics, it was difficult to get the amount of blur identical; nonetheless, the results look fairly similar — maybe the lens blur is a little crisper. That could partially be because I didn’t blur it quite as much, but I think its range of tones is also a little different.
I’m getting to like the lens blur effect. It feels like it gives you a little better control. Right now I’m working on a book about the Chinese artist Zhan Wang. For this book I’ve applied some selective lens blurring to some of the images. Following is an example — original photo on top and modified photo beneath. For this image I applied a quick mask to select the figures and foreground rocks, then lens blurred the rest. (Of course I also did my usual adjustments.) Do you like this effect?
Russel Brown has an interesting sequence of tutorials on working with video in Photoshop.
- In part one he demonstrates combining two video sequences using a layer mask
- In part two he shows how to blend objects over time
- In part three he explores spot colorization and looks further at video blending and painting over time
These techniques require CS3 — guess I’m going to have to upgrade my software.
Let’s have a little fun tilt-shifting San Francisco‘s Pioneer Monument. I choose the Pioneer Monument for a couple of reasons: I look down on it out my window at work, and I find it offensive with its glorification of Frisco fat cat robber barons and its demeaning portrayal of Native Americans. Ready? We’ll want to keep the pigeonshit on main figure’s head in focus. Here goes. Wheee!
Wasn’t that fun? Many people see this effect as creating the illusion of a miniaturized landscape. You can do it, or something very like it, with an extremely expensive camera called a “tilt-shift” (whence the name of the effect). Or you approximate the effect in five or ten minutes of Photoshop.
The technique is described, with a few variations, in many places around the web. You can check it out on your search engine. Or, you can just read on.
I process most images that I post to the web in Photoshop, and I have a simple workflow that does what I want with a minimum of fuss. The whole process only takes a minute or two. Allow me to demonstrate.
I’ve chosen an image more or less at random (except that it is one that I like, from this photoset). My vantage point was looking down at a river from overhead, with colorful leaves on the right. For the purpose of this demonstration the image has been resized to fit this space (435 pixels wide).
The first thing I do is to open an action I’ve saved under the name “open adjustments.” This opens three adjustment layers: levels, curves, and hue/saturation in that order, which is the order I make the adjustments.
First I look at levels. If they look well balanced I might leave them alone. Often they are weighted to either darks or lights, and I slide the midtone triangle to get a better balance. That often makes the image look worse but it puts it in position for the next adjustment, curves. Usually I find a midpoint that looks good and then generally make an ess-shaped curve in order to get a good range of darks and lights. Finally, I adjust hue/saturation. With my current camera this usually means just increasing the saturation a little bit.
Next I open an action I’ve saved under the name “hi-pass sharpen.” This sharpens the image using the duplicate layer – invert – blur – overlay – adjust transparency workflow that I have described previously. I don’t like oversharpening, so my default transparency is a modest 40 percent. It’s important to remember to select the background layer first or you will just be sharpening your hue/saturation adjustment. One nice thing about this way of sharpening is that it is size independent, so I can resize my image and do a save for web to reduce the file size without having to resharpen.
The entire process is done with adjustment layers and is completely nondestructive — no changes are made to the original image. Below the image as it came from the camera is on the left and the adjusted image on the right.
I’ve written about restoring dark images before, but the other day I was working on a less radical image than the ones I was writing about then, and I thought a more detailed step-by step tutorial might be in order. In the image above — a picture of the western group of ruins at the Maya site of Kabah in the Yucatan — the original is on the left and the corrected version on the right. Follow me through the process here.