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halftoning

Thresholding with a Pattern

Last time, I used the Cumulative Distribution Function of an image’s intensity to make a black and white image. This time, I’ll use a different pattern as the basis for halftoning the image.  For example, I’ll use the following pattern of circles on a regular grid: This time, instead of finding a threshold from the […]

Categories
halftoning

Partitionless Halftoning

We’ve looked at two halftoning methods using thresholding: either directly on the image, or using a pattern. These require making subdivisions of the image to get any decent spatial resolution. Instead, we can specify properties of the pattern such that the pattern itself acts as a threshold. The black and white image can then be […]

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halftoning

Intro to Halftoning

The general idea behind halftoning is to render an image using a very limited number of colors. On this blog, I’ll focus particularly on rendering black and white images. The following image is the Lena test image, and its grayscale version (converted in MATLAB). I’ll be using these for most of the approaches that I […]

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map

Earth as a Disc

I wanted an equal-area projection of the earth onto a disk. This is a simple one. We’ll use spherical coordinates, with polar angle and azimuthal angle . This means that latitude is, in radians, , and longitude is . We’ll say that the sphere has a radius of . We’ll have the North pole at […]