R: Image transformation: rotation, resize, etc.

resize {EBImage}

R Documentation

Image transformation: rotation, resize, etc.

Description

Functions to rotate, mirror and resize images.

Usage

    affinet(x, sx=0, rx=0, ry=0, sy=0, tx=0, ty=0, ...)
    flip(x, ...)
    flop(x, ...)
    resample(x, w, h, ...)
    resize(x, w, h, blur=1, ...)
    rotate(x, angle=90, ...)

Arguments

x: An object of Image-class.
sx, rx, ry, sy, tx, ty: Elements of the affine matrix.
w, h: Width and height of a new resized/resampled image. One of these arguments can be missing to enable proportional resize.
blur: The blur factor, where 1 (TRUE) is blurry, 0 (FALSE) is sharp.
angle: Image rotation angle in degrees.
...: Reserved for future use.

Value

A transformed image in an object of Image-class.

Details

affinet transforms an image as dictated by the affine matrix.

flip creates a vertical mirror image by reflecting the pixels around the central x-axis.

flop creates a horizontal mirror image by reflecting the pixels around the central y-axis.

resample scales an image to the desired dimensions with pixel sampling. Unlike other scaling methods, this method does not introduce any additional color into the scaled image.

resize scales an image to the desired dimensions with one of the filters that can be set using the Image-class accessor method sampleFilter. Most of the filters are FIR (finite impulse response), however, Bessel, Gaussian, and Sinc are IIR (infinite impulse response). Bessel and Sinc are windowed (brought down to zero) with the Blackman filter.

rotate creates a new image that is a rotated copy of an existing one. Positive angles rotate counter-clockwise (right-hand rule), while negative angles rotate clockwise. Rotated images are usually larger than the originals and have 'empty' triangular corners. X axis. Empty triangles left over from shearing the image are filled with the background color.

Author(s)

References

ImageMagick: http://www.imagemagick.org.