Extra Polynymous
The simplest type of cross-hatching is to have a set number of hatching angles and constant spacing. The header image shows the result with 16 different angles. This can be extended to use other sorts of patterns. For example, here are orthogonal circular and radial lines: The number of overlapping lines was computed for each […]
I’ve mentioned that subdividing an image is useful for putting patterns within the divisions. This method uses the outline of the subdivisions to provide the darkness. The way this is done is to repeatedly break a shape into two parts: ensuring that the ratio of perimeter to blackness within is equal on both sides. From […]
I saw an interesting algorithm for creating branching veiny patterns called the Space Colonization Algorithm. Of course, I had to apply it to halftoning. Basically, the veins grow in the direction of their nearest destination points. Once the vein is close enough to a destination point, that destination is removed from the list, and growth […]
I’ve been interested lately in approximating images using lines of constant width. To that end, I’ve made these: These patterns are grown iteratively. A shape begins growing from the unclaimed point closest to the center of the image. By sampling the brightness of the image, the size of the new shape is chosen such that […]
Let’s apply the half-toning techniques to the separate color channels of an image, like the header image above. Or the one below, where the stripes are no longer aligned with the gradients. This can be done with any of the halftoning methods, but the stripes have character.
How can we draw pictures with dots? This is called stippling, which involves putting a lot of dots across an image to approximate tones. On a white background, more (or larger) black dots result in a locally darker image. These two approaches are known as AM and FM stippling. AM – amplitude modulation – means […]
On the theme of using a single path to shade an image, one idea is to use a wiggling line. A shorter wavelength will result in a darker area, and vice versa. So I threw a little math at the problem, and here are the results of using square, triangle waves, and sine waves: A […]
Those other stripes are nice sometimes, but what about varying the orientation and wavelength of the stripes? As before, the output can be formed by varying the wavelength or the width of the stripes. Here are comparisons of the two approaches on the Lena: Now how about the crossed patterns? Much improved, compared to the […]
A quick one: the phase field can be computed as the scaled distance from edges in the image. Then apply the stripes math, and: This has reasonably interesting circular artifacts, but it is limited in how it responds to the image.
What if we want stripes to respond to an image? Well, we can make a version of the image that has gradients that are roughly parallel to those of the original image. Then we can use those as the basis of some stripes. Say we want a phase field that has gradients that are parallel […]