imager (version 0.31)

index.coord: Linear index in internal vector from pixel coordinates

Description

Pixels are stored linearly in (x,y,z,c) order. This function computes the vector index of a pixel given its coordinates

Usage

index.coord(im, coords, outside = "stop")

Arguments

im

an image

coords

a data.frame with values x,y,z (optional), c (optional)

outside

what to do if some coordinates are outside the image: "stop" issues error, "NA" replaces invalid coordinates with NAs. Default: "stop".

Value

a vector of indices (NA if the indices are invalid)

See Also

coord.index, the reverse operation

Examples

im <- as.cimg(function(x,y) x+y,100,100)
px <- index.coord(im,data.frame(x=c(3,3),y=c(1,2)))
im[px] #Values should be 3+1=4, 3+2=5