wavelet based color compression
DESCRIPTION
Wavelet Based Color Compression. Greg Beranek. Background. WDR Significance Pass With threshold T and T2 find item where T2>Item>=T Encode the Address Encode Plus or Minus Repeat Refinement Pass If Item >=T2 Write Refinement Repeat. WDR. Color WDR. Significance Pass Three Passes - PowerPoint PPT PresentationTRANSCRIPT
WAVELET BASED COLOR COMPRESSIONGreg Beranek
BACKGROUND WDR
Significance Pass With threshold T and T2 find item where T2>Item>=T
Encode the Address Encode Plus or Minus
Repeat Refinement Pass
If Item >=T2 Write Refinement
Repeat
WDR
COLOR WDR Significance Pass
Three Passes Red Pass Green Pass Blue Pass
Refinement Three Passes
Red Green Blue
COLOR WDR
ISSUES COLOR WDR Progressive nature
Cannot stop anywhere (missing color component)
Speed 3 Passes 3 Scan orders 3 data matrices
Accounting
RESOLUTION TO COLOR WDR ISSUES Color Correlation (lack of correlation)
Ability to predict significant values Encode more data with one color and get a very
close color when decoding Simplify scan order
COLOR SPACE Primitive Color Spaces
RGB Additive color space Tells how much light is needed to make a specific color
CYM K Subtractive color space Tell what quantity of pigment is needed to make a
specific color Other Color Spaces
YUV YPbPr (YCbCr)
Video and Image Compression Schemes, Analog (Digital)
YCoCg Integer to Integer Color space similar to YPbPr
TRANSFORM MATRIX RGB TO YCOCG Forward - RGB -> YCoCg
Reverse - YCoCg -> RGB
BACK TO COLOR WDR We now have the ability to:
Predict significant color values
Simplify to one scan order
Retain some RGB color information when we stop encoding anywhere
COLOR WDR
OPTIMIZATIONS
Encoder optimizations
ASWDR
Lossy Color Space
HOW GOOD IS THIS COMPARED TO JPEG 2000?
PSNR from Color Compression of Lena
1bpp (24:1) 0.5bpp (48:1)
JPEG2000 34.320604 32.239947
Color WDR 33.414003 31.180589
PSNR from Color Compression of Parrots (kodim23)
1bpp (24:1) 0.5bpp (48:1)
JPEG2000 40.553139 37.526301
Color WDR 38.60774 34.599361
PSNR from Color Compression of Hats (kodim03)
1bpp (24:1) 0.5bpp (48:1)
JPEG2000 39.946701 35.951137
Color WDR 34.542265 32.215072
PICTURES LENA
Left : Original (Cropped)Top Right : Color WDR 1 bppBottom Right : JPEG 2000 1 bpp
PICTURES HATS
Left : Original (Cropped)Top Right : Color WDR 1 bppBottom Right : JPEG 2000 1 bpp
PICTURES PARROTS
Left : Original (Cropped)Top Right : Color WDR 1 bppBottom Right : JPEG 2000 1 bpp
QUESTIONS?