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 19972 days, 9 hours, 14 minutes ago.