OpenImageR (version 1.3.0)

warpAffine: Warp Affine

Description

Warp Affine

Usage

warpAffine(img, M, R, C, threads = 1, verbose = FALSE)

Value

either a matrix or a 3-dimensional array (where the third dimension is equal to 3)

Arguments

img

either a matrix or a 3-dimensional array (where the third dimension is equal to 3) with a range of values between 0 and 255

M

a matrix corresponding to the transformation matrix

R

a value corresponding to the destination number of rows

C

a value corresponding to the destination number of columns

threads

an integer specifying the number of threads to run in parallel. This parameter applies only if the input "img" parameter is of type matrix.

verbose

a boolean. If TRUE then information will be printed in the console

References

https://github.com/OlehOnyshchak/ImageTransformations/blob/master/AffineTransformation.ipynb

Examples

require(OpenImageR)

path = system.file("tmp_images", "landscape.jpg", package = "OpenImageR")
img = readImage(path)
img = img * 255

#.............................
# compute the affine transform
#.............................

r = ncol(img)
c = nrow(img)
offset = 50

original_points = matrix(data = c(0, 0, r, 0, 0, c),
                         nrow = 3,
                         ncol = 2,
                         byrow = TRUE)

transformed_points = matrix(data = c(offset, 0, r, offset, 0, c-offset),
                            nrow = 3,
                            ncol = 2,
                            byrow = TRUE)

M_aff = getAffineTransform(original_points = original_points,
                           transformed_points = transformed_points)

#..............
# 2-dimensional
#..............

img_2d = rgb_2gray(img)

res_2d = warpAffine(img = img_2d,
                    M = M_aff,
                    R = r,
                    C = c,
                    threads = 1,
                    verbose = TRUE)

# imageShow(res_2d)

#..............
# 3-dimensional
#..............

res_3d = warpAffine(img = img,
                    M = M_aff,
                    R = r,
                    C = c,
                    verbose = TRUE)

# imageShow(res_3d)