colorillusion.frink

use Writer.frink

// This program generates color illusions like this:
// http://www.johnsadowski.com/big_spanish_castle.php

inputURL = "file:DSC_0077.JPG"
img_in = new image[inputURL]

// Get file part of URL to use for output files.
origFile = urlFile[inputURL]
greyFile = origFile
greyFile =~  %s/(.*)\.\w+\$/\$1grey.jpg/
colorFile = origFile
colorFile =~ %s/(.*)\.\w+\$/\$1colors.jpg/
htmlFile = origFile
htmlFile  =~ %s/(.*)\.\w+\$/\$1.html/

Width = img_in.getWidth[]
Height = img_in.getHeight[]

reverseImg = new image[Width, Height]
greyImg = new image[Width, Height]

for w = 0 to Width-1
{
for h = 0 to Height-1
{
[r,g,b] = img_in.getPixel[w, h]
// This converts to YUV space using the BT. 709 definition used in
// HDTV.  See http://en.wikipedia.org/wiki/YUV
y =  0.2126  r + 0.7152  g + 0.0722  b
u = -0.09991 r - 0.33609 g + 0.436   b
v =  0.615   r - 0.55861 g - 0.05639 b

// Write out the grayscale levels.
greyImg.setPixel[w, h, y, y, y]

// Now we're going the throw away the Y (luminance) component
// and replace it with a constant 0.5.  Then we're going to go back to
// RGB space and reverse the colors.  We could simplify these equations
// but it's kinda nice to see them in this form.
y = 0.5
r = y +       0 u + 1.28033 v
g = y - 0.21482 u - 0.38059 v
b = y + 2.12798 u -       0 v
reverseImg.setPixel[w, h, 1-r, 1-g, 1-b]
}
}

g = new graphics
g.fitCenter[reverseImg, 0, 0, 1, 1]
g.drawEllipseCenter[0,0,0.005, 0.005]
//win = g.show[Width, Height]
g.write[colorFile, Width, Height]

g1 = new graphics
g1.fitCenter[greyImg, 0, 0, 1, 1]
g1.drawEllipseCenter[0,0,0.005, 0.005]
g1.write[greyFile, Width, Height]

// Render an interactive HTML file
println["htmlFile is \$htmlFile"]
html = new Writer[htmlFile]
html.write["""<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"
"http://www.w3.org/TR/html4/loose.dtd">
<HTML LANG="en">
<HEAD>
<TITLE>\$htmlFile</TITLE>
</HEAD>
<BODY>
<CENTER>
<P>
Stare at the dot for 30 seconds, then move your mouse over the image.
</P>

<P>
<IMG NAME="i1" SRC="\$colorFile" onMouseOver="document.i1.src='\$greyFile'" onMouseOut="document.i1.src='\$colorFile'">
</P>
</CENTER>
</BODY>
</HTML>"""]
html.close[]

println["Interactive file rendered to \$htmlFile"]

// Start the interactive HTML file in the browser.
browse[htmlFile]

/*for i = 1 to 10
{
win.replaceGraphics[g1]
sleep[5 s]
win.replaceGraphics[g]
sleep[30 s]
}*/

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 18664 days, 10 hours, 59 minutes ago.