Zhang-Suen thinning algorithm: Difference between revisions
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=={{header|J}}==
'''Solution:'''
<lang j>isBlackPx=: '1'&=;._2 NB. boolean array of black pixels
toImage=: [: , LF ,.~ '01' {~ ] NB. convert to original representation
frameImg=: 0 ,. 0 , >:@$ {. ] NB. adds border of 0's to image
nbrs=: adverb define NB. applies verb u to neighbourhoods
(1 1 ,: 3 3) u;._3 y
)
Bdry=: 1 2 5 8 7 6 3 0 1 NB. map pixel index to neighbour order
getPx=: { , NB. get desired pixels from neighbourhood
Ap1=: [: +/ 2 </\ Bdry&getPx NB. count 0->1 transitions
Bp1=: [: +/ [: }. Bdry&getPx NB. count black neighbours
c11=: (2&<: *. <:&6)@Bp1 NB. step 1, condition 1
c12=: 1 = Ap1 NB. ...
c13=: 0 e. 1 5 7&getPx
c14=: 0 e. 5 7 3&getPx
c23=: 0 e. 1 5 3&getPx NB. step2, condition 3
c24=: 0 e. 1 7 3&getPx
step1=: c11 *. c12 *. c13 *. c14 NB. step1 conditions
step2=: c11 *. c12 *. c23 *. c24 NB. step2 conditions
whiten=: [ * -.@:*. NB. make black pixels white
zhangSuen=: [: toImage [: (whiten [: frameImg step2 nbrs)@(whiten [: frameImg step1 nbrs)^:_ isBlackPx
zhangSuenX=: verb define NB. alternative Explicit representation of verb above
img=. isBlackPx y
whilst. 0 < +/ , msk1 +.&-. msk2 do.
msk1=. (-.@:*. [: frameImg step1 nbrs) img
img=. msk1 * img
msk2=. (-.@:*. [: frameImg step2 nbrs) img
img=. msk2 * img
end.
toImage img
)
</lang>
'''Example Use:'''
<lang j>toASCII=: ' #' {~ '1'&=;._2 NB. convert to ASCII representation
ExampleImg=: noun define
00000000000000000000000000000000
01111111110000000111111110000000
01110001111000001111001111000000
01110000111000001110000111000000
01110001111000001110000000000000
01111111110000001110000000000000
01110111100000001110000111000000
01110011110011101111001111011100
01110001111011100111111110011100
00000000000000000000000000000000
)
toASCII zhangSuen ExampleImg
####### ######
# # ##
# # #
# # #
##### # #
## #
# # ## ## #
# ####
</lang>
=={{header|Perl 6}}==
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