opencv (version 0.5.1)

opencv-area: OpenCV area manipulation

Description

Manipulate image regions

Usage

ocv_rectangle(image, x = 0L, y = 0L, width, height)
ocv_polygon(image, pts, convex = FALSE, crop = FALSE, color = 255)
ocv_bbox(image, pts)
ocv_chull(pts)

Arguments

image

an ocv image object

x

horizontal location

y

vertical location

width

width of the area

height

height of the area

pts

a list of points with elements x and y

convex

are the points convex

crop

crop the resulting area to its bounding box

color

color for the non-polygon area

Examples

mona <- ocv_read('https://jeroen.github.io/images/monalisa.jpg')

# Rectangular area
ocv_rectangle(mona, x = 400, y = 300, height = 300, width = 350)
ocv_rectangle(mona, x = 0, y = 100, height = 200)
ocv_rectangle(mona, x = 500, y = 0, width = 75)

# Polygon area
img <- ocv_resize(mona, width = 320, height = 477)
pts <- list(x = c(184, 172, 146, 114,  90,  76,  92, 163, 258),
            y = c(72,   68,  70,  90, 110, 398, 412, 385, 210))
ocv_polygon(img, pts)
ocv_polygon(img, pts, crop = TRUE)
ocv_polygon(img, pts, convex = TRUE, crop = TRUE)

# Bounding box based on points
ocv_bbox(img, pts)

# Bounding box of non-zero pixel area
area <- ocv_polygon(img, pts, color = 0, crop = FALSE)
area
area <- ocv_bbox(area)
area

# \dontshow{
ocv_destroy(mona)
ocv_destroy(img)
ocv_destroy(area)
# }