License:	GPL-2 | GPL-3 [expanded from: GPL (≥ 2)]
Title:	Simple Unified Interface to Read Bitmap Images (BMP,JPEG,PNG,TIFF)
Description:	Identifies and reads Windows BMP, JPEG, PNG, and TIFF format bitmap images. Identification defaults to the use of the magic number embedded in the file rather than the file extension. Reading of JPEG and PNG image depends on libjpg and libpng libraries. See file INSTALL for details if necessary.
Version:	0.1.5
URL:	https://github.com/jefferis/readbitmap
BugReports:	https://github.com/jefferis/readbitmap/issues
SystemRequirements:	libjpeg, libpng
Imports:	bmp, jpeg, png, tiff
Suggests:	pixmap, testthat
RoxygenNote:	6.0.1
NeedsCompilation:	no
Packaged:	2018-06-27 11:45:09 UTC; jefferis
Author:	Gregory Jefferis [aut, cre], Derek Ogle [ctb], Simon Barthelme [ctb]
Maintainer:	Gregory Jefferis <jefferis@gmail.com>
Repository:	CRAN
Date/Publication:	2018-06-27 13:48:52 UTC

readbitmap: read standard bitmap image formats

Description

The readbitmap package enables users to read the three main general purpose bitmap image formats (jpeg, png, bmp) without having to specify the image type directly. This is provided by a single function read.bitmap, which uses a second function image_type, which is also exported for users, to identify the image type of a file using appropriate magic values encoded in the first few bytes of the image header. Images can therefore have any file extension.

See Also

image_type, read.bitmap

Identify the type of an image using the magic value at the start of the file

Description

Currently works for png, jpeg, BMP, and tiff images. Will seek to start of file if passed a connection. For details of magic values for files, see e.g. http://en.wikipedia.org/wiki/Magic_number_(programming)#Magic_numbers_in_files

Usage

image_type(source, Verbose = FALSE)

Arguments

Value

character value corresponding to standard file extension of image format (i.e. jpg, png, bmp, tif) or NA_character_ on failure.

Examples

jpegfile=system.file("img", "Rlogo.jpg", package="jpeg")
image_type(jpegfile)
jpeg_pretending_to_be_png=tempfile(fileext = '.png')
file.copy(jpegfile, jpeg_pretending_to_be_png)
image_type(jpeg_pretending_to_be_png)
unlink(jpeg_pretending_to_be_png)

Read in a bitmap image in JPEG, PNG, BMP or TIFF format

Description

By default uses magic bytes at the start of the file to identify the image type (rather than the file extension). Currently uses readers in bmp, jpeg, png, and tiff packages.

Usage

read.bitmap(f, channel, IdentifyByExtension = FALSE, ...)

Arguments

Value

Objects returned by readJPEG, readPNG, read.bmp, or readTIFF. See their documentation for details.

See Also

image_type, readJPEG, readPNG, read.bmp, readTIFF

Examples

img1=read.bitmap(system.file("img", "Rlogo.jpg", package="jpeg"))
str(img1)
img2 <- read.bitmap(system.file("img", "Rlogo.png", package="png"))
# nb the PNG image has an alpha channel
str(img2)