image_connect component number collision

[aavogt]

Below is self-contained example of image_connect assigning the same number to two pixels that are not connected. It only happens when there are too many components as determined by N.

library(magick)

N <- 21 # must be odd to get a grid instead of strips
w <- image_blank(N, N, color = "white")
b <- image_blank(1, 1, color="black")
get_row <- function(i) i %% N
get_col <- function(i) i %/% N
# NxN alternating 1x1 white and black squares
bw <- Reduce(function(w, i) {
                w2 <- image_composite(w, b, offset = paste0("+", get_row(i), "+", get_col(i)) )
                image_destroy(w)
                w2 },
        seq(1, N*N, by=2),
        w)
        
# bw %>% image_resize("400%") %>% image_browse

# FALSE for N >= 17 when there are collisions but
# TRUE for N <= 15 when there are no collisions
image_connect(bw) %>%
         image_raster %>%
         (function(x) all(table(x$col) == 1) )

image_connect could output a color image to encode components after component number 255. Or if that's not possible without changing the c++, I would like a warning that there are too many components for each to get a unique number.