Monday, July 25, 2011

Creating svg graphics for web publishing

Thanks to the nice post from Revolution Analytics I was finally able to get an svg device working on my Windows OS version of R. It took some additional tips from a fellow user of blogger to figure out out how to embed the result on (due to the inability to upload svg files I had to post the file on Wikimedia Commons and then create a link).

Luckily, I didn't need to rebuild my R version with cairo support - i just installed the R package Cairo and then used its function CairoSVG()

the code for the figure...

Wednesday, July 6, 2011

Color reduction of an image - and Warholize?

There seems to be several methods out there for reducing the colors in an image. I became interested in this after pondering how this is done in the excellent freeware program IrfanView. Unfortunately, their method is not described anywhere that I could find, but I imagine that it is something along the tree data structure collapse method that ImageMagick employes.

The biOps package employes the k-means clustering to arrive at a reduced number of colors. I find that while this method takes a bit longer, the results can actually look a lot better. Just for kicks, I imbedded the imgKMeans() function in another function called warholize() that replaces these reduced color levels with another set. It's definitly not a Warhol, but I still like the effect.

the function...