How are your figures (images?) represented in R? If you use an efficiently vectorized function on an image represented as a triple of matrices or a 3xnxm array, I wouldn't expect things to be too slow.
You can resize easily using R's indexing for arrays. E.g., centerOfImage <- wholeImage[,251:750,251:750] using a 3x1000x1000 array wholeImage. Certain operations you'd like to do on images are best done as C code called from R's .Call interface. For example, local median filters. Depending on the representation of images you're using, it might be easy to use libraries like ImageMagick or vigra for example in this way. Reid Huntsinger -----Original Message----- From: Francisco do Nascimento Junior [mailto:[EMAIL PROTECTED]] Sent: Wednesday, January 22, 2003 9:10 AM To: R-help Subject: [R] Performance Hello, I'm applying an arithmetical function the color (R,G,B) of each pixel of a figure and it's very slow. This is common? Other thing, are there some library to make modification in figures, eg, to alter size? If not, somebody knows some software that makes this, or either, to resize figures automatically, therefore I go to need to apply to a bank. Tks, Francisco. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ Francisco J�nior, Computer Science - UFPE-Brazil "One life has more value that the world whole" ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ______________________________________________ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help ------------------------------------------------------------------------------ ______________________________________________ [EMAIL PROTECTED] mailing list http://www.stat.math.ethz.ch/mailman/listinfo/r-help
