Download or view decheckerboard.frink in plain text format
// Program to reverse-engineer an illusion by Akiyoshi Kitaoka:
// https://twitter.com/AkiyoshiKitaoka/status/844356094369513473
// Save the full-sized image from that post into this directory, named
// checkerboard.jpg
i = new image["file:checkerboard.jpg"]
[w,h] = i.getSize[]
i2 = new image[w,h]
for x = 0 to w-1
for y = 0 to h-1
{
[r,g,b] = i.getPixelInt[x,y]
// Reproduce the grid and subtract it out
phase = (x div 9 + y div 9) mod 2
if phase == 0
{
r = r + 114
g = g + 114
b = b + 114
} else
{
r = r - 116
g = g - 116
b = b - 116
}
// Stretch contrast
r = (r - 128) * 3 + 128
g = (g - 128) * 3 + 128
b = (b - 128) * 3 + 128
if (r < 0 or g < 0 or b < 0 or r > 255 or g > 255 or b > 255)
println["Error at $x $y: $r $g $b (phase is $phase), pixel was " + i.getPixelInt[x,y]]
i2.setPixelInt[x, y, r,g,b]
}
i2.show[]
i2.write["decheckerboard.jpg"]
Download or view decheckerboard.frink in plain text format
This is a program written in the programming language Frink.
For more information, view the Frink
Documentation or see More Sample Frink Programs.
Alan Eliasen was born 19971 days, 19 hours, 39 minutes ago.