Image Processing

1
Image Processing Computer Vision

• Optical Flow Motion

2
Optical Flow Motion
Optical Flow ?????? ?????????????? ???????????????
?????? ???? ? ???????????? ??? Frame ??? t1 ???
Frame ??? t2
(a) Time t1 (b) Time t2 (c) Optical Flow
3
Optical Flow Motion
Example of Application using Optical Flow Motion
4
Constraints ?????? Optical Flow ??????????? Gibbs
Sampler

1. Data Constraints ? ??????????????????????????
   ????????????????????? (image intensity)
   ??????????????????????????? ??????????????????????
   ? Vector u ??? v
2. Smoothness Constraints ? ??? u ??? v ??????
   smooth ?????????? ?????????????? u ??? v ???
   ?????????? (neighbor) ??????? ??????????????????

Energy ?xy (It(x,y) - It1(xv(x,y),yu(x,y))
)2 ?(u(x1,y) u(x,y))2
?(u(x,y1)
u(x,y))2
?(v(x1,y) v(x,y))2
?(v(x,y1) v(x,y))2

Data Constraints
Smoothness Constraints
5
Algorithm using Gibbs Sampler

• 1. Start Temperature T is high
• 2. Initialize u(x,y) Random -20...20
• Initialize v(x,y) Random -20...20
• 3. For each pixel(x,y)
• For each state Su -2020
• For each state Sv -20..20
• if u(x,y) -20 and v(x,y) -20 E-20,-20
  P-20,-20 exp(-E-20,-20/T)
• if u(x,y) -20 and v(x,y) -19
  E-20,-19 P-20,-19 exp(-E-20,-19/T)
• .
• if u(x,y) 20 and v(x,y) 19 E20,19
  P20,19 exp(-E20,19/T)
• if u(x,y) 20 and v(x,y) 20 E20,20
  P20,20 exp(-E20,20/T)
• For each Probi Pi / sum(Pi)
• 4. Sample for state S from pdf Probui and Probvi
• u(x,y) State Su v(x,y) State Sv
• 5. Reduce T T 0.9
• 6. Repeat step 3-4 Until E is stable

6
Optical Flow Motion using Gibbs Sampler
Framet1
Framet
u and v
Optical Flow
7
Example
Framet1
Framet
v value
u value
8
Example
Framet1
Framet
Random u value
Random v value
9
Image Processing Computer Vision

• Motion From 2D Image Sequence

10
Motion Detection Example
Input Image
Image Subtraction
Region of Motion
11
Motion Detection Algorithm (????
??????????????????????????? background)

• Input ??? video ?????????? sequence
  ???????????????? Time (????) ?????????????? Frame
  Ft1i,jFtni,j
• For all pixelsi,j in current frame
• set Iouti,j 1 if IFti,j IFt1i,j
  gt T
• ???? Iout ??????????????????? ???????????????????
  ???????? ??????? Iout ??????????????? ???????
  ???????????? ??? ????????? ???????????????????????
  ????? ?????????????????????????
• ?? connected components ??? Iout ?????????? blob
  coloring ???? ??? projection
• ????? Remove ??????????? ? (small region)
  ??????????????????? ? ???? noise

threshold
12
Motion Detection Algorithm (???? background ?????)

• ????? remove ??????????? ? ??? (Size Filtering)
  ????????????????????????? ????????
• ?????????????????????????????? ????????????????
  frame ???????????? ???????????????????????????????
  ???????????????????????

13
Example
Framet1
Framet
Image Subtraction (Iout)
Motion Object
14
Example
Framet1
Framet
Image Subtraction (Iout)
Motion Object
15
Size Filtering

• Size Filtering ???????????(remove)
  ????????????????????????????????????????????
  Framet ??? Framet1
• ????????????????????????????????????????
  threshold(T) ?????????? ??????????????????????????
  ?????? T ??????????????????????????? ??? set ???
  ???????????????? ? ????????? ????????

???????????? T20
??????????? ??????????? ? ?? ?????????????
16
?????????????? Motion Detection ???
???????????????????????

• ???????? Motion Detection 2D ?????????????????????
  ?????????????????????????????????????
• ????? Motion Detection 2D ????????????????????????
  ?????????????????????? 360 ????

17
????????????????????????????????
Framet
Framet1
Center Area
Center Area

• ?????????????? different image ?????????????? 20
  ???????????? ????????????????
• ????????? ?????????????????? different image
  ?????? Frame
• -????????????????? pixel ????? ??????????? ,????
  ?????? ?????? Frame
• -??????????????????????? ????????????????????????
  ?????????????????????? ???? ???? ????, ????
  ??????
• -?????????????? ???? ???? ???? ???? ???
  ??????????????????????????????????????
  ??????????????????
• ??? ????.?.??????? ??????? ????.?.?????? ??????
  ????.?.??????? ???????????

18
???????????????????????????????? (Example)
Framet
????????? 20 ??????????????????
????????????? ????????? 20 ???????
(20 x20)/100 4 - ????????????????????????
4 pixel - ??????????????????????? 4 pixel -
????????????????????? 13 - ???.?. center
13 ??????? ?.?. ????????????
???????????????????? ???
(13x100)/13 100 - ???.?. left 0 ???????
?.?. ???? ????????????????????
(0x100)/13 0 - ???.?. right 0 ???????
?.?. ??? ????????????????????
(0x100)/13 0 ??????? ???????????
Center Area
19
???????????????????????????????? (Example)
Framet1
????????? 20 ??????????????????
????????????? ????????? 20 ???????
(20 x20)/100 4 - ????????????????????????
4 pixel - ??????????????????????? 4 pixel -
????????????????????? 13 - ???.?. center 9
??????? ?.?. ???????????? ???????????????????
? ??? (9x100)/13 69.23 -
???.?. left 4 ??????? ?.?. ????
???????????????????? (4x100)/13
30.77 - ???.?. right 0 ??????? ?.?. ???
???????????????????? (0x100)/13
0 ??????? ???????????
Center Area
20
???????????????????????????????? (Example)
Framet2
????????? 20 ??????????????????
????????????? ????????? 20 ???????
(20 x20)/100 4 - ????????????????????????
4 pixel - ??????????????????????? 4 pixel -
????????????????????? 13 - ???.?. center 1
??????? ?.?. ???????????? ???????????????????
? ??? (1x100)/13 7.69 -
???.?. left 0 ??????? ?.?. ????
???????????????????? (0x100)/12
0 - ???.?. right 0 ??????? ?.?. ???
????????????????????
(12x100)/13 92.30 ???????
????????????????
Center Area
21
????????????????????????????,??????
Top
Top right
Top left
Center
Right
Left
Bottom
Bottom left
Bottom right
???????????????????????? 6 ???? ??? top left,
top, top right, left, center, right, bottom left,
bottom, bottom right
22
????????????????????????????,??????(example)
????????? 20 ??????? 20/3 6.67 7 ???????
??????????? 7 pixels ?????????? 7
pixels ??????????????????????? 6 pixels
??????? 10 ??????? 10/3 3.33 3 ???????
?????????? 3 pixels ???????????? 3
pixels ??????????????????????? 4 pixels
23
????????????????????????????,??????(example)
Framet
- ???.?. center 2 ??????? ?.?.
???????????????????? (2x100)/27
7.40 - ???.?. right 2 ??????? ?.?.
???????????????????? (2x100)/27
7.40 - ???.?. bottomleft 0 ??????? ?.?.
???????????????????? (0x100)/27
0 - ???.?. bottom 1 ??????? ?.?.
???????????????????? (1x100)/27
3.70 - ???.?. bottomright 1 ??????? ?.?.
???????????????????? (1x100)/27
3.70
- ????????????????????? 27 - ???.?.
topleft 14 ??????? ?.?.
???????????????????? ???
(14x100)/27 51.85 - ???.?. top 1 ???????
?.?. ????????????????????
(1x100)/27 3.70 - ???.?. topright 0
??????? ?.?. ????????????????????
(0x100)/27 0 - ???.?. left 6 ???????
?.?. ????????????????????
(6x100)/27 22.22
???????????????????? topleft