agg_tiff {ragg}

Draw to a TIFF file

Description

The TIFF (Tagged Image File Format) format is a very versatile raster image storage format that supports 8 and 16bit colour mode, true transparency, as well as a range of other features not relevant to drawing from R (e.g. support for different colour spaces). The storage mode of the image data is not fixed and different compression modes are possible, in contrast to PNGs one-approach-fits-all. The default (uncompressed) will result in much larger files than PNG, and in general PNG is a better format for many of the graphic types produced in R. Still, TIFF has its purposes and sometimes this file format is explicetly requested.

Usage

agg_tiff(
  filename = "Rplot%03d.tiff",
  width = 480,
  height = 480,
  units = "px",
  pointsize = 12,
  background = "white",
  res = 72,
  scaling = 1,
  snap_rect = TRUE,
  compression = "none",
  bitsize = 8,
  bg
)

Arguments

filename

The name of the file. Follows the same semantics as the file naming in grDevices::png(), meaning that you can provide a sprintf() compliant string format to name multiple plots (such as the default value)

width, height

The dimensions of the device

units

The unit width and height is measured in, in either pixels ('px'), inches ('in'), millimeters ('mm'), or centimeter ('cm').

pointsize

The default pointsize of the device in pt. This will in general not have any effect on grid graphics (including ggplot2) as text size is always set explicitly there.

background

The background colour of the device

res

The resolution of the device. This setting will govern how device dimensions given in inches, centimeters, or millimeters will be converted to pixels. Further, it will be used to scale text sizes and linewidths

scaling

A scaling factor to apply to the rendered line width and text size. Useful for getting the right dimensions at the resolution that you need. If e.g. you need to render a plot at 4000x3000 pixels for it to fit into a layout, but you find that the result appears to small, you can increase the scaling argument to make everything appear bigger at the same resolution.

snap_rect

Should axis-aligned rectangles drawn with only fill snap to the pixel grid. This will prevent anti-aliasing artifacts when two rectangles are touching at their border.

compression

The compression type to use for the image data. The standard options from the grDevices::tiff() function are available under the same name.

bitsize

Should the device record colour as 8 or 16bit

bg

Same as background for compatibility with old graphic device APIs

Transparency

TIFF have support for true transparency, meaning that the pixel colour is stored in pre-multiplied form. This is in contrast to pixels being stored in plain format, where the alpha values more function as a mask. The utility of this is not always that important, but it is one of the benefits of TIFF over PNG so it should be noted.

Note

'jpeg' compression is only available if ragg is compiled with a version of libtiff where jpeg support has been turned on.

Examples

file <- tempfile(fileext = '.tiff')
# Use jpeg compression
agg_tiff(file, compression = 'lzw+p')
plot(sin, -pi, 2*pi)
dev.off()