-- Sharpen_Luminance.lua
-- apply a sharpening convolution to the value channel.
-- author: Dan Ritchie
-- modified for Pixopedia 24 by Sinisa Petric, 2008  

image_OUT = 0
image_INP = 1


kernel = { { -1, -1,  -1},
           { -1,  12,  -1},
           { -1, -1,  -1} }
divisor = 4
offset = 0


function filter (x,y)
   local i, j, sum, v2 , dummy1, dummy2
   sum = 0

   for i=-1,1 do
      for j=-1,1 do
         dummy1,dummy2,v2= fp24_getImageHSV(image_INP, x+i, y+j)
         sum = sum + (kernel[j+2][i+2] * v2)
      end
   end
   return (sum / divisor) + offset
end



for y=0, vp24_height-1 do
   for x= 0, vp24_width-1 do
       h,s,v = fp24_getImageHSV(image_INP, x,y)
       v = filter (x,y)
       fp24_setImageHSV (image_OUT, x,y,h,s,v)
   end
   fp24_showProgress (y, vp24_height)
end