chart <- function (samp.width = 0.01){
file <- list.files(path = "./vis")[1]
vis.jpeg <- readJPEG(paste("./vis/", file, sep = ""))
vis.red <- raster(vis.jpeg[, , 1])
vis.green <- raster(vis.jpeg[, , 2])
vis.blue <- raster(vis.jpeg[, , 3])
rgb <- stack(vis.red, vis.green, vis.blue)
options(warn = -1)
plotRGB(rgb, scale = 1, asp = nrow(vis.red)/ncol(vis.red))
options(warn = 0)
chart.coords <- data.frame(x = numeric(), y = numeric())
message("Click on all 24 color chart cells in sequence. The sequence follows left to right and starts at cell 1 (brown, top left) and finishes on cell 24 (black, bottom right).")
for (i in 1:24) {
options(warn = -1)
chart.coords[i, 1:2] <- click(xy = T)[1:2]
options(warn = 0)
}
sp.chart <- SpatialPoints(chart.coords)
chart.buff <- gBuffer(sp.chart, width = samp.width, byid = T)
plot(chart.buff, add = T, col = "green")
return(chart.buff)
}
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