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Background Blurring. [email protected] Outline. Introduction Documentation Object Segmentation Depth Map Generation Image Defocus. Perspective Box. Lazy Snapping. Camera Settings. Pop-up Card. Defocus Blur. Privacy Preserving. Photo Browser. Method. Depth Map Generation.

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outline
Outline
  • Introduction
  • Documentation
    • Object Segmentation
    • Depth Map Generation
    • Image Defocus
method

Perspective Box

Lazy Snapping

Camera Settings

Pop-up Card

Defocus Blur

Privacy Preserving

Photo Browser

Method

Depth Map Generation

Perspective Box

Object Segmentation

Pop-up Card

Applications

Lazy Snapping

Image Defocus

Camera Settings

method1
Method

User Stroke

Resize to 20%

  • Segment
    • Lazy snapping
    • Mean shift

Mean shift

Do hard graph cut by lazy snapping

Lazy Snapping. ACM Trans. On Graphics 2004.

Mean Shift: A Robust Approach Toward Feature Space Analysis. PAMI 2002.

A Bayesian Approach to Digital Matting. CVPR 2001.

method2
Method

Perspective Box

Pop-up card

Pop-up card

  • Depth map
    • Perspective Box
      • Vanish point
      • Rear wall

Normal vector

Normal vector

Depth Map

Depth Map

Tour Into the Picture: Using a spidery mesh user interface to make animation from a single image. SIGGRAPH 1997

method3
Method

Perspective Box

Pop-up card

Pop-up card

  • Depth map
    • Pop-up card

Normal vector

Normal vector

Depth Map

Depth Map

method4
Method

Perspective Box

Pop-up card

  • Depth map
    • Normal vector

Normal vector

Normal vector

Depth Map

Depth Map

method5
Method
  • Defocus blur
    • bokeh

x

method6
Method
  • Defocus blur
method7
Method
  • Near-by object case

Focus on the flower

Focus on the flower

method8
Method

Blur circle diameter

Objects in front of the focus

Objects behind

the focus

  • Near-by object case

Blur shape as alpha map

Texture synthesis inpainting

Defocus Blur

Defocus Blur

Interpolation by alpha map

Shallow focus image

experimental result 1
Experimental Result 1
  • Defocus blur method proposed in the system comparing with other blur filter results

Deep focus

Shallow focus

experimental result 11
Experimental Result 1
  • Defocus blur method proposed in the system comparing with other blur filter results

Gaussian blur

Defocus blur

Defocus blur + Bokeh

experimental result 12
Experimental Result 1

Deep focus

Shallow focus

experimental result 13
Experimental Result 1

Original photograph

  • Defocus blur method proposed in the system comparing with other blur filter results

Gaussian blur

Defocus blur

Defocus blur + Bokeh

experimental result 2
Experimental Result 2
  • Near-by object case

Focus on the flower

Focus on the flower

experimental result 21
Experimental Result 2
  • Near-by object case

Interpolation result

Without inpainting

slide24

./ 系統主要分成三部份,前兩塊產生出depth和segment的資訊之後,可以在第三部份根據不同參數設定產生出不同的效果

    • system
      • 1_segmentation
        • Tool1: lazy-snapping with simple UI
        • Tool2: 光影魔術手
      • 2_depthmap
        • depth of background scene (3d-box)
        • depth of each segment
      • 3_refocusblur
        • camera parameter
        • refocusing (inpainting, defocus blur)
    • sample // sample input, parameter and result
slide25

Segmentation

    • Lazy snapping
      • Tool1: preprocessing(resize for mean shift ) + lazy snapping
      • Lzsegment.m
        • Input : parameter file name

先做preprocessing,這裡可以用meanshift或是直接downsample成64色階,並且在meanshift的地方resize為五分之一加快速度,

讀取stroke_1.bmp, stroke_2.bmp…等前後景筆劃圖,前景是紅色,後景是藍色。然後執行lazy snapping處理

◎每個segment都存一個灰階的bmp檔,檔名分別是seg_1.bmp, seg_2.bmp…沒有先後順序。將每個segment扣除剩下的background的部份,即是seg_segN.bmp

◎需要libgil2的library

      • Tool2:光影魔術手
      • 每個segment都存一個png檔,檔名分別是obj_1.png, obj_2.png…將這些png檔的alpha值轉成bmp, 並且扣除只剩下background的部份,即是seg_segN.bmp
slide26

Depth map

    • depth.m(function depth(parafilename))
      • Input:
        • parameter file name
        • dep_1.dat, dep_2.dat, …dep_(segN-1).dat

★ 每個dep_n.dat的內容:

nxny

p1x p1y

p2x p2y

★ n表示normal vector, 預設是 (0,0), vector方向代表物體在平面上的法向量方向,長度表示深度變化量

★ p1,p2…是user劃下的筆劃座標,即此segment的深度參考點,預設是segment最下方的點。如果沒有p1,p2…系統會自動取segment最下方一列的點作為參考點。

      • Output:
        • dep_1.bmp, dep_2.bmp … dep_segN.bmp
slide27

Refocus Blur

    • refocus.m

( function [finalresult]=defocus(parafilename) )

      • Get parameter from file, and load the segment/depth bmp files
      • Get the focus position from focusposition.dat
      • Compute diffusion blur circle diameter for each pixel
      • Devide image into two parts, the part in front of the focus, and run defocus_blur.m
      • Use alpha.m to get alpha map, and find the pixels to run inpaint.m
      • Use the result by inpaint.mto call defocus_blur.m
      • Combine the front part and back part by alpha map
      • return the result image
slide28

others

    • Inpainting function needs the estexemplarhelper.c

run mexestexemplarhelper.cbefore the function call at first time

The inpainting code (inpaint.m) is from http://www.cc.gatech.edu/~sooraj/inpainting/

    • Meanshift code is downloaded from
    • http://www.caip.rutgers.edu/riul/
input parameter file
Input parameter file
  • 1.dirnamediratory of the files, include \'/\' on the tail, ex: \'sample1/\'
  • 2.imagename file name of input image, ex: test.jpg
  • 3.segN number of segment image, include the background.

ex: 2 (foreground*1+background)

  • 4.vx position of vanish point, must be in the rear wall,
  • 5.vy but can be outside of the image
  • 6.ax
  • 7.ayleft_top position of the rear wall
  • 8.bx
  • 9.byright_bottom position of the rear wall
  • 10.dc_f lens focal length,(mm) ex: 50 mm, 100 mm ...etc.
  • 11.dpmax the depth of pixels with color level 255 in depth map, (mm)
  • 12.dnear the depth of pixels with color level 0 in depth map, (mm)
  • 13.dc_N the aperture number
  • 14.thr=250 threshold of bokeh color level
  • 15.light_e=0.5 little constant number for light_weight function
  • 16.lens shape default setting 0 is flat disk
slide31

Camera parameter

  • dc_f相機的焦距,單位是mm,數值越大景深越淺,

建議在50~100之間

  • Dpmax rear wall距離成像平面的距離,建議為5~50公尺 (5000~50000)
  • Dnear場景裡距離成像平面最近的物體距離,

建議為1公尺,至少要在兩倍焦距以上

  • dc_N光圈值,數值越大,光圈孔隙越小,景深越深,

為達到淺景深效果建議值在1.4~2.8之間,越小效果越強

  • thr=250將pixel產生散景效果的臨界值,建議不要低於240
  • light_e=0.5 weight function的明度微調參數,為一個大於0的值,

數值越大明度影響越低,建議為0.5~1之間

  • lens shape 光圈孔隙的形狀,預設為0

對應到refocus/lens/ 資料夾底下的0.bmp, 1.bmp

slide32

Sample

    • ./
      • parameter01-.dat
    • ./sample01
      • original image
      • seg_1.bmp seg_2.bmp …
      • dep_1.dat dep_2.dat …
        • 可由UI產生
      • focusposition.dat
        • 可由UI產生,給定要聚焦的點,可以為單一或是多個點,將會取其對應到的深度平均值,格式為

x1 y1

x2 y2

      • dep_1.bmp dep_2.bmp …
slide33

執行:

    • 用system的前兩步驟產生出前頁所述的參數和bmp files,並放在所屬資料夾下
    • result = refocus(parameter file name);
slide34

END

THANK YOU

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