adimpro: I/O Functions

In adimpro: Adaptive Smoothing of Digital Images

I/O Functions

Description

Create image objects of class "adimpro" from arrays, RAW-format files and other image formats.

Usage

read.raw(filename, type="PPM",
         wb="CAMERA",cspace="Adobe",interp="Bilinear",maxrange=TRUE,
         rm.ppm=TRUE, compress=TRUE)
read.image(filename, compress=TRUE)
make.image(x,compress=TRUE, gammatype="None", whitep = "D65", 
         cspace="Adobe", scale="Original",xmode="RGB")

Arguments

filename	file name
x	Array or matrix containing RGB or greyscale values in the range (0,1) or (0,65535).
type	option settings for dcraw. default "PPM". type="png" allows to read greyvalue png images as RAW-data (used as internal solution to store RAW information)
wb	white balance. default "CAMERA"
cspace	defines the output color space, default "sRGB" (sRGB D65), alternatives are "RAW" (Camera specific), "Adobe" (Adobe 1998 D65), "wGamut" (Wide Gamut D65), "kodak" (Kodak ProPhoto D65) and "XYZ", see manpages of dcraw.
interp	defines the interpolation method, default "Bilinear", Alternatives are "VNG", "AHD", "FourC" (Four color interpolation) and "Halfsize", see manpages of dcraw. "VNG" seems to provide the smallest spatial correlations.
maxrange	If TRUE increase range of values to maximum.
rm.ppm	remove intermediate tmp file? default TRUE
gammatype	character, determines the type of gamma correction within the image. "ITU" stands for ITU-R BT.709-3 as e.g. used by dcraw. Alternatives recognized within the package are "None", "sRGB" and "CIE" (CIE L*). Please specify if you know that your image is not gamma corrected using ITU-R BT.709-3.
whitep	White point in xyY space. Can be given as one of (character) c("A","B","C","E","D50","D55","D65","D75","F2","F7","F11") or as a two element numeric vector of chromatic xy coordinates. "D65" corresponds to the default white point of "sRGB" and "Adobe" RGB-spaces.
compress	logical, determines if image data are stored in raw-format.
scale	"Original" scales to (0,max(img$img)) if min(img$img)<0, otherwise keeps the original scale. "Maxcontrast" scales each channel to maximum contrast
xmode	xmode determines how to interpret the values in x if length(dim(x))==3. Implemented are xmode="RGB" (default) and xmode="HSI"

Details

If ImageMagick is available on the system, read.image reads any of the following image file formats: c("tif", "tiff", "pgm", "ppm", "png", "pnm", "gif", "jpg", "jpeg") converts it into a temporary "pgm" or "ppm" file. This file is removed after reading the image. If ImageMagick is not available only "pgm", "ppm" and "pnm" formats can be processed.

If dcraw is available on the system, read.raw reads many RAW formats. type sets options to dcraw: "PPM" sets "-4", "RAW" sets "-4 -d", "HALFSIZE" sets "-h", "INFO" sets "-i -v". wb indicates, which white balance should be used: "NONE", "AUTO", "CAMERA".

Functions read.raw(file,type="RAW") and read.image(file) provide identical results on png-mages. If the result is a color, greyvalued or RAW image depends on the contend of the comment associated with the png-image.

make.image converts an appropriate 2 or 3 dimensional array to an image object of class "adimpro".

Value

object of class "adimpro" containing the image. The object has the following components:

img	array containing the color values in the color space specified by value$type.
type	the color space.
depth	color depth, here "16bit".
dim	vector of length 2 containing the number of pixel in horizontal and vertival direction.
file	the argument file identifying the image.
cspace	the type of rgb space used, as specified by cspace.
interp	interpolation applied by dcraw, as specified by interp.
gamma	has a gamma correction been applied, here FALSE for read.raw and TRUE for read.image
gammatype	type of gamma correction read.image.
wb	type of white balance, as specified by wb.
compressed	image data are stored as raw-vector (TRUE) or array of integers (FALSE).

Note

The function read.raw requires dcraw to be installed.

Author(s)

Karsten Tabelow [e-mail] and Joerg Polzehl [e-mail]

See Also

read.image

Examples

## Not run: demo(io)

adimpro documentation built on Sept. 30, 2024, 9:17 a.m.