Class 36 — November 26
Image visualization
I draw from the past – Wonder about the present – Think of the future
Look both ways
HW Downloads — do not download until asked to
Sepia
 There is no one formula for defining a Sepia pixel conversation. The one used here comes from Microsoft.
 For pixel
(r,g,b)
, the Sepia conversion is(sr,sg,sb)
where
sr, sg, sb = int( min( i, 255 )), int( min( j, 255 )), int( min( k, 255 )),
where
i, j, k
are
i = .393r + .769g + .189b
j = .349r + .686g + .168b
k = .272r + .534g + .131b
Palette reduction
 Sometimes to save computer memory, software developers perform a palette reduction of colors used in image representation.
 Our reduction scheme will use an eightcolor palette
 Black, White, Red, Green, Blue, Yellow, Magenta, and Cyan; that is,
(0,0,0), (255,255,255), (255,0,0), (0,255,0), (0,0,255), (255,255,0), (255,0,255),
and(0,255,255)
 In a palette reduction, a pixel
(r,g,b)
is replaced by the pixel in in the palette it is closest to. The distance between pixels(r1,g1,b1)
and(r2,g2,b2)
equals
abs(r1  r2) + abs(g1  g2) + abs(b1  b2)
 
  
