rgb_2_10bit.R

#!/usr/bin/env Rscript
# -*- encoding: utf-8 -*-
# ./10bit.R
#
# (c) 2010 Konstantin Sering, Nora Umbach, Dominik Wabersich
# <colorlab[at]psycho.uni-tuebingen.de>
#
# GPL 3.0+ or (cc) by-sa (http://creativecommons.org/licenses/by-sa/3.0/)
#
# content: finds 10 bit gray values for 3 channels RGB
#
# input: --
# output: 10bit_reslist.txt
#         grey_dict.py  
#
# created
# last mod 2012-05-29, NU

color <- 0:255/255
grey <- 0:1023/1023

# Create all combinations
dat <- expand.grid(r=color,g=color,b=color)
# Calculate grey results for all combinations
dat$grey <- with(dat, r*.299 + g*.587 + b*.114)

# or data after grey
# (not really necessary)
dat <- dat[order(dat$grey),]

# Find elements next to grey in dat
reslist <- NULL
for (i in 1:1024){
    x <- dat[which.min(abs(dat$grey - grey[i])),]
    reslist <- rbind(reslist, x)
    gc() #free all memory R doesn't need anymore
}

# save rdata
#save(dat,reslist, file="10bit.rdata") ## around 100 MB
write.table(reslist, file="10bit_reslist.txt", quote=F, row=F)
#write.table(dat, file="10bit_dat.txt") ## around 1.3 GB

# calculate the corresponding integer values (0,255) for RGB
reslist$Rint <- reslist$r*255
reslist$Gint <- reslist$g*255
reslist$Bint <- reslist$b*255
reslist$GREYint <- round(reslist$grey*1023, 0)

# write python code to file
f <- file("grey_dict.py")
writeLines( paste("grey_dict = {\n", with(reslist,
paste(GREYint, ": (", Rint, ",", Gint, ",", Bint, ")", sep="",
collapse=",\n")), "}\n", sep=""), f)
close(f)