Blog Archives

Interview with Sacha Chua

I spoke with with Sacha Chua last week. We talked about entrepreneurship, Emacs, having eclectic interests, delegation, and more. J: I ran into you by searching on Emacs topics. When I look at your blog, I see that you do

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R without Hadley Wickham

Tim Hopper asked on Twitter today: #rstats programming without @hadleywickham’s libraries is like ________ without _________. Some of the replies were: (skydiving, a parachute) (gouging your own eyes out, NULL) (dentistry, anesthesia) (shaving, a razor) (internet shopping, credit card) Clearly

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Interview with Michael Hammel, author of The Artist's Guide to GIMP

Michael J. Hammel is the author of The Artist’s Guide to GIMP, a book I reviewed three weeks ago. The following interview is based on my correspondence with Michael.

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The Artist's Guide to GIMP

Learning how to edit images has been on my to-do list for a long time. I do some very basic editing with Paint.NET, but I keep meaning to learn to use GIMP. I heard years ago that GIMP is terribly

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Thoughts on the new Windows logo

I appreciate spare design, but the new Windows logo is just boring. Here’s the rationale for the new logo according to The Windows Blog: But if you look back to the origins of the logo you see that it really

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Including LaTeX in an Inkscape drawing

My previous post described how to include an Inkscape drawing in a LaTeX document. This post describes how to use LaTeX in an Inkscape drawing, which is probably more useful. The LaTeX output is included not as bitmap but as

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Including an Inkscape drawing in LaTeX

The Inkscape drawing package can export to a large variety of vector drawing formats, including LaTeX. If you save your drawing to a file foo.tex, you can include the file in a LaTeX document as follows. \documentclass{article} \usepackage{pstricks} \begin{document} Testing

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Function plots in Inkscape

Why would you want to plot a mathematical function using a drawing package like Inkscape rather than a mathematical package like Mathematica or R? One reason is that you may want plot for its visual properties. For example, you might

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Bezier basics

Bézier curves are very common in computer graphics. They also interesting mathematical properties. This post will give a quick introduction to Bézier curves, describing them first in visual terms and then in mathematical terms. There are different degrees of Bézier

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Same color illusion

Are squares A and B are the same color? I found this illusion on John Baez’s site. It was created by Edward Adelson in 1995 and is the subject of a Wikipedia article. Related post: Optical illusion, mathematical illusion

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More on colors and grayscale

My previous post gave three algorithms for converting color to grayscale. This post gives more examples and details. The image below is a screenshot from an Excel spreadsheet illustrating color values and how the convert to grayscale. The R, G,

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Three algorithms for converting color to grayscale

How do you convert a color image to grayscale? If each color pixel is described by a triple (R, G, B) of intensities for red, green, and blue, how do you map that to a single number giving a grayscale

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Optical illusion, mathematical illusion

Someone sent me a link to an optical illusion while I was working on a math problem. The two things turned out to be related. In the image below, what look like blues spiral and green spirals are actually exactly

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Posted in Graphics, Math

PNG vs JPEG

Bill the Lizard answered an image compression question on StackOverflow by pointing out the image below that shows the difference between PNG and JPEG compression when applied to line drawings. The image comes from lbrandy.com. The left side of the

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Picking a color scheme

The other day Nils gave an interesting answer to a question on StackOverflow regarding color theory.  NEVER ever use pure colors. … If you have no idea what color to start with, get a classic masterpiece of painting from the

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Posted in Creativity, Graphics