Optimized seam carving for Julia

seam_carving.jl

function find_min_energy_map2(energy)
   energy = transpose(energy)
   row, col = size(energy)
   dir_arr = [-1, 0, 1]

   energy_map = zeros(row, col)
   energy_map[:, end] = energy[:, end]
   dirs = zeros(Int, row, col)

   @inbounds for c = col-1:-1:1
       local_energy, next_element = min2(energy_map[1, c+1], energy_map[2, c+1])
       energy_map[1, c] = local_energy + energy[1, c]
       dirs[1, c] = dir_arr[next_element+1]
       @inbounds for r = 2:row-1
           top = max(1, r - 1)
           bottom = min(row, r + 1)

           local_energy, next_element = min3(energy_map[r-1, c+1], energy_map[r, c+1], energy_map[r+1, c+1])
           energy_map[r, c] += local_energy + energy[r, c]
           dirs[r, c] = dir_arr[next_element]
       end
       local_energy, next_element = min2(energy_map[row-1, c+1], energy_map[row, c+1])
       energy_map[row, c] = local_energy + energy[row, c]
       dirs[row, c] = dir_arr[next_element]
   end

   return transpose(energy_map), transpose(dirs)
end

function min2(a, b)
   return (a < b) ? (a, 1) : (b, 2)
end

function min3(a, b, c)
   if (a < b)
       if (a < c)
           return a, 1
       else
           return c, 3
       end
   else
       if (b < c)
           return b, 2
       else
           return c, 3
       end
   end
end