Home/ Questions/Q 5974265
In Process

The Archive Base Latest Questions

Editorial Team
  • 0
Asked: 2026-05-22T20:55:09+00:00

I’ve noticed that when I add alpha parameter to a geom all text on

  • 0

I’ve noticed that when I add alpha parameter to a geom all text on the graph (axis titles, etc.) get darker (almost as if they have become bold) when output is PDF. This doesn’t seem to be tied to the actual alpha value. It makes the charts a lot harder on the eyes, particularly when there are multiple charts per page with lots of text. Has anyone else experienced this?

compare the following (probably a bad example because there is little text…but if maximize on the same screen and toggle between them you’ll see the difference)

pdf(FILE_HERE1)
p <- ggplot(mtcars, aes(wt, mpg)) 
p = p + geom_point() 
print( p )
dev.off()


pdf(FILE_HERE2)
p <- ggplot(mtcars, aes(wt, mpg)) 
p = p + geom_point( alpha=.2) 
print( p )
dev.off()
Share

Leave an answer

You must login to add an answer.

Need An Account,

1 Answer

  1. Editorial Team

    My finding is that this has nothing to do with perception, and perhaps something to do with the fact that I’m mixing graphics types:
    R – adding page numbers to PDF

    If I run ghostscript on my PDF then the bold/darker effect disappears. I’m running ghostscript to embed a font into my PDF. A positive side-effect is that my PDFs shrink in size considerably. I know very little about ghostscript, so I’m not sure if this is generalizable or simply a consequence of the specific way I’m using ghostscript.

    • 0