Artificial Mosaic Generation with Gradient Vector Flow and Tile Cutting

Algorithm 1

Mosaic generation algorithm.

Input: A Raster Image 𝐼

Output: Artificial Mosaic of Image 𝐼

begin

 𝐿(𝐼) = Luminance(𝐼)

 𝐺(𝐼) = Robert’s Gradient(Equalize(𝐿(𝐼)))

 [𝑢,𝑣] = 𝐺𝑉𝐹(|𝐺(𝐼)|_∞, μ, 𝑛𝐼𝑡𝑒𝑟𝑎𝑡𝑖𝑜𝑛𝑠)

 𝑔𝑣𝑓(𝐼) = 𝑢²+𝑣^21/2

 Sort in queue 𝑄 pixels (𝑖,𝑗) according to decreasing

 𝑔𝑣𝑓(𝑖,𝑗) values. Only pixels whose 𝑔𝑣𝑓 is greater

 than a threshold 𝑇 go into 𝑄.

 while  𝑄 is not empty do

  Extract pixel 𝑃 from 𝑄

  Place a tile in 𝑃 at angle

  𝛼 = tan^−l(𝑣(𝑖,𝑗)/𝑢(𝑖,𝑗))

  if  in this way the tile overlaps with previously

  placed tiles then

   Skip tile positioning

 for  𝑗 = 1 to   length(𝐼) do

  for  𝑖 = 1 to   width(𝐼) do

   Place a tile in the pixel(𝑖,𝑗) at angle

   𝛼 = tan^−l(𝑣(𝑖,𝑗)/𝑢(𝑖,𝑗))

   if  in this way the tile overlaps with

   previously placed tiles then

    Skip tile positioning

end