Message-ID: <e936a3d0807301921r9476447w298d0cfc989808c8@mail.gmail.com>
Date: 2008-07-31T02:21:56Z
From: Fán Lóng
Subject: How to generate 24-bit PNG on Mac OSX
Hi there,
When I am using the png() function as the following to generate a PNG
file on Mac OSX Tiger, I found that the bit depth is 32. But I need
24 bit depth PNG. What should I do?
> png(filename="/Users/usg/Desktop/new.png")
> plot(1:20)
> dev.off()
To avoid using "cairo", and R-2.7.0 does not find a Xlib on my Mac, I
also tried this one:
> png(filename="/Users/usg/Desktop/new.png", type ="quartz" )
> plot(1:20)
> dev.off()
It does not work, either.
The manual says "png will use a palette if there are less than 256
colours on the page, and record a 24-bit RGB file otherwise (or a
32-bit RGBA file if type = "cairo" and non-opaque colours are used)."
I don't have to set the palette less than 256 colours, I just want a
true color png file.
Any help is appreciated.
Thanks in advance.
Long