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# 國　立　中　正　大　學　電　機　工　程　學　系 隊伍名稱：室友是中正仔仔 專題題目：數位影像處理－放大與縮小 指導教授：黃崇勛教授 參展學生：何宗興、鈕采紋 - PowerPoint PPT Presentation

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Presentation Transcript

Motivation

?

Computer

1440x900

Cell phone

480x320

4K TV

3840x2160

1024 x768

1280x720

Scaling down

Scaling up

• 基本的內插法
• 縮小原理
• Nearest Neighbor Interpolation

取走間隔像素

從已知點建構出未知點

• Drawbacks
• Drawbacks
• 丟點失真
• 資訊遺漏
• 影像模糊
• 鋸齒邊緣
• ProposedAlgorithm

(a)原始影像(b)目的影像

• BilinearInterpolation
• 邊緣偵測

1.邊緣偵測

2.直方圓分割

(a)原始影像(b)目的影像

圖像在邊緣的部分像素質會有較大的變化，利用sobel邊緣偵測運算元子，來計算出圖像邊緣

• ProposedAlgorithm

1.一般縮放

2.剪裁縮放

3.魚眼效果

4.調變比例適應

D1=|S1-S2|，D2=|S1-S3|

D3=|S1-S4|，D4=|S2-S3|

D5=|S2-S4|，D6=|S3-S4|

• 直方圖分割

Start

S2

S1

T

• Type1:vertical

Edge

detection

S3

S4

(1) min = D2 and D3 >Th and D4 >Th(2) min = D5 and D3 >Th and D4 >Th

Yes

No

• Type2:horizontal

Edge

region

Non-edge

region

直方圖統計出圖像中各像素的數量，再用閥值對圖像做分割

(1)min = D1 and D3 >Th and D4 >Th(2)min = D6 and D3 >Th and D4 >Th

• Type3:SW-NE

Edge-directed

interpolation

Bilinear

(1)min = D4 and ( D1 >Th or D6 >Th )(2) (min = D1 or min= D2 ) and (min2 = D1 or min2= D2 or min2= D4 ) and (D5 >Th and D6 >Th )

• 現有的縮放
• Type4:NW-SE

Output scaled pixel

• 調變比例縮放

(1) min = D3 and ( D1 >Th or D6 >Th)(2) (min = D2 or min= D6 ) and (min2 = D2 or min2= D3 or min2= D6 ) and (D1 >Th and D5 >Th )

給予重要物在屏幕上顯示的比例增強，可以更清楚了解圖像內容又不失其周邊之資訊

End

t=(1.2-R)^2*0.2 R’=R+t

Results

• Scaling-down
• Scaling-up

References

[1] Image Retargeting Using Mesh Parametrization Yanwen Guo, Feng Liu,Jian Shi,Zhi-Hua Zhou,

Senior Member, IEEE, and Michael Gleicher

[2] Video Adaptation for Small Display Based on Content Recomposition,

Wen-Huang Cheng, Student Member, IEEE, Chia-Wei Wang, and Ja-Ling Wu, Senior Member,

IEEE

[3] Yen-Tai Lai, Chao-Feng Tzeng and Hung-Chu Wu, “Adaptive Image Scaling Based on Local

Edge Directions”

[4]繆紹綱,“數位影像處理-活用Matlab”

[5]鍾國亮,“影像處理與電腦視覺 ”

[6]劉鴻明,蔡孟達,張元翔, “應用於影像縮放技術之內插法評估研究”

[7]洪瑋隆,“內插影像放大之邊緣強化技術”

[8]林榮朗,“動態及靜態影像放大之研究”

Proposed

Bilinear

一般縮小

調變比例縮小