Progressive medical image transmission and compression Author : R. S. Dilmaghani, A. Ahmadian, M. Ghavami, A. H. Aghvami Source : IEEE Signal Processing Letters, Volume. 11, No. 10 Speaker : Pay-Chai Chang (張培才)

Outline Introduction Introduction to EZW Resolution Constraint Bit-Rate Constraint Progressive Transmission of a ROI of an Image Conclusion

Introduction (1/2) 離散小波轉換 a+b c+d a-b c-d a b c d A B C D A B C D 20 15 30 17 16 31 22 18 25 21 19 35 50 5 10 33 53 1 9 42 3 -8 43 37 -1 A B C D A B C D A+B C+D A-B C-D 68 103 6 19 76 79 2 -7 -3 4 1 -10 5 -9 326 -38 6 19 16 -32 2 -7 -3 4 1 -10 5 -9

Introduction (2/2) LL1 HL1 LH1 HH1 第一階 第二階 第三階 影像最重要 的部分 HL2 LH2 HH2

Introduction to EZW (1/5) T0 =2 log2(max(Cij)) = 2 log263 = 25 = 32 R = (max(Cij) + T0 ) / 2 = ( 63 +32 ) / 2 = 48 POS (ex : 63) NEG (ex : -34) ZTR (ex : 23) IZ (ex : -31)

Introduction to EZW (2/5) 63 R2=40 R1=56 D1 S1 A1 = 0 (之前的重要係數) Max (Cij)

Introduction to EZW (3/5) T1 = T0 / 2 = 32 / 2 =16 R = 48 / 2 = 24 A2 S2 直到 Tk = 0 或使用者認為可以為止

Introduction to EZW (4/5) Max (Cij)(63) => T0 => R(48) => R1(56) , R2(40) D1 : POS,NEG, IZ, ZTR, POS, ZTR, ZTR, ZTR, ZTR, IZ, ZTR, ZTR, ZTR, ZTR, ZTR, ZTR, ZTR, POS, ZTR, ZTR S1 : 1010 A1 = 0

Introduction to EZW (5/5) A2 = 1001

Resolution Constraint (1/3) Resolution Constraint specified the maximum number of scales or subbands to be scanned and refined during zerotree passes. Bit rate (EZW編碼結果所佔大小) Scale 1 2 3 4 5… Resolution(I) 2-1 2-2 2-3 2-4 2-5

Resolution Constraint (2/3) LL3 HL1 LH1 HH1 HL2 LH2 HH2 LL2 HL1 LH1 HH1 HL2 LH2 HH2 LL2 Scale : 2 , I = 2-2 Scale : 3 , I = 2-3 PSNR , bit rate : scale 2 > scale 3 仍使用threshold 來達成漸進式傳輸 多使用了 resolution 來限制

Resolution Constraint (3/3)

Bit-Rate Constraint (1/2) 設定 Bit-Rate Constraint , 各 resolution 掃描到該值則停止

Bit-Rate Constraint (2/2)

Progressive Transmission of a ROI of an Image

Conclusion The results shows that the compression performance obtained by the EZW is superior over JPEG-2000, especially at higher compression ratios.