Hi, I experienced a problem with the "rgb()" function. These two calls should (and do) return identical results:
rgb(255, 128, 128, maxColorValue=255) rgb(1.0, 0.5, 0.5, maxColorValue=1) However, when I specify a non-default "alpha" channel (a "transparent" colour), I get differing results: rgb(255, 128, 128, alpha=0.5, maxColorValue=255) rgb(1.0, 0.5, 0.5, alpha=0.5, maxColorValue=1) where only the latter version seems to yield the actually intended result. Is this a bug? You can check the actual colours' appearance this way: barplot(3:5, col=rgb(255, 128, 128, maxColorValue=255)) barplot(3:5, col=rgb(1.0, 0.5, 0.5, maxColorValue=1)) barplot(3:5, col=rgb(255, 128, 128, alpha=0.5, maxColorValue=255)) barplot(3:5, col=rgb(1.0, 0.5, 0.5, alpha=0.5, maxColorValue=1)) The apparently buggy version in this case seems to return white instead of red. Thanks, Christian ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
