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Zhang-Suen thinning algorithm: Difference between revisions
Add lua solution
(Add Haskell - Zhang-Suen Thinning Algorithm) |
(Add lua solution) |
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# ############
### ### </pre>
=={{header|Lua}}==
<lang lua>function zhangSuenThin(img)
local dirs={
{ 0,-1},
{ 1,-1},
{ 1, 0},
{ 1, 1},
{ 0, 1},
{-1, 1},
{-1, 0},
{-1,-1},
{ 0,-1},
}
local black=1
local white=0
function A(x, y)
local c=0
local current=img[y+dirs[1][2]][x+dirs[1][1]]
for i=2,#dirs do
local to_compare=img[y+dirs[i][2]][x+dirs[i][1]]
if current==white and to_compare==black then
c=c+1
end
current=to_compare
end
return c
end
function B(x, y)
local c=0
for i=2,#dirs do
local value=img[y+dirs[i][2]][x+dirs[i][1]]
if value==black then
c=c+1
end
end
return c
end
function common_step(x, y)
if img[y][x]~=black or x<=1 or x>=#img[y] or y<=1 or y>=#img then
return false
end
local b_value=B(x, y)
if b_value<2 or b_value>6 then
return false
end
local a_value=A(x, y)
if a_value~=1 then
return false
end
return true
end
function step_one(x, y)
if not common_step(x, y) then
return false
end
local p2=img[y+dirs[1][2]][x+dirs[1][1]]
local p4=img[y+dirs[3][2]][x+dirs[3][1]]
local p6=img[y+dirs[5][2]][x+dirs[5][1]]
local p8=img[y+dirs[7][2]][x+dirs[7][1]]
if p4==white or p6==white or p2==white and p8==white then
return true
end
return false
end
function step_two(x, y)
if not common_step(x, y) then
return false
end
local p2=img[y+dirs[1][2]][x+dirs[1][1]]
local p4=img[y+dirs[3][2]][x+dirs[3][1]]
local p6=img[y+dirs[5][2]][x+dirs[5][1]]
local p8=img[y+dirs[7][2]][x+dirs[7][1]]
if p2==white or p8==white or p4==white and p6==white then
return true
end
return false
end
function convert(to_do)
for k,v in pairs(to_do) do
img[v[2]][v[1]]=white
end
end
function do_step_on_all(step)
local to_convert={}
for y=1,#img do
for x=1,#img[y] do
if step(x, y) then
table.insert(to_convert, {x,y})
end
end
end
convert(to_convert)
return #to_convert>0
end
local continue=true
while continue do
continue=false
if do_step_on_all(step_one) then
continue=true
end
if do_step_on_all(step_two) then
continue=true
end
end
for y=1,#img do
for x=1,#img[y] do
io.write(img[y][x]==black and '#' or ' ')
end
io.write('\n')
end
end
local image = {
{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
{0,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0,1,1,1,1,1,1,1,1,0,0,0,0,0,0,0},
{0,1,1,1,0,0,0,1,1,1,1,0,0,0,0,0,1,1,1,1,0,0,1,1,1,1,0,0,0,0,0,0},
{0,1,1,1,0,0,0,0,1,1,1,0,0,0,0,0,1,1,1,0,0,0,0,1,1,1,0,0,0,0,0,0},
{0,1,1,1,0,0,0,1,1,1,1,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0},
{0,1,1,1,1,1,1,1,1,1,0,0,0,0,0,0,1,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0},
{0,1,1,1,0,1,1,1,1,0,0,0,0,0,0,0,1,1,1,0,0,0,0,1,1,1,0,0,0,0,0,0},
{0,1,1,1,0,0,1,1,1,1,0,0,1,1,1,0,1,1,1,1,0,0,1,1,1,1,0,1,1,1,0,0},
{0,1,1,1,0,0,0,1,1,1,1,0,1,1,1,0,0,1,1,1,1,1,1,1,1,0,0,1,1,1,0,0},
{0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},
}
zhangSuenThin(image)
</lang>
Output:
<pre>
####### ######
# # ##
# # #
# # #
##### # #
## #
# # ## ## #
# ####
</pre>
=={{header|Mathematica}}==
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