2. Software Verification Environment Plan (Initial)
• Development of YCbCr input and RGB Input at different
Resolutions: (Initial target)
- Generate RGB reference inputs with 565/555/444 resolutions.
- Generate input reference YCbCr data 4:2:2 or 4:2:0 data.
- Initial Target: Minimum visual degradation.
- Dithering Algorithms for this step does not have to target hardware.
- Start with simple dithering algorithms to get environment going.
- Statistical optimal color quantization algorithms could be used at a later stage.
- Golden reference models can be used to compate visual quality and PSNR.
• Output color Dithering for reduced bit width output
– The intention of these algorithms is to reduce the bit-width of the output
from ARGB8888 to a format that is characterized by a reduced number of
bits per channel
– Dithering algorithms applied are intended to be implemented on the actual
IP hardware.
– Dithering Algorithm has to be efficient and hardware implementable.
2
3. 3
Direct YCbCr 4:2:0/4:2:2 input files
Y
Cr
Cb
ARGB8888
Computations
Color
Conversion
YCbCr
Input files
Video
Decode
YCbCr
2D IP & Verification Env
4. 4
2D IP Env: conversion for YCbCr 4:2:0
Cr
Cb
2→
2→
Cr
Cb
Y
ARGB8888
Computation
YCrCb
4:2:2
YCrCb
4:4:4
YCbCr->RGB
Cr
Cb
YCrCb
4:2:0
2→2→ 2D IP & Verification
Environment
5. 5
2D IP Env: conversion for YCbCr 4:2:2
Cr
Cb
2→
2→
Cr
Cb
Y
ARGB8888
Computation
YCrCb
4:2:2
YCrCb
4:4:4
YCbCr->RGB
2D IP & Verification
Environment
6. Generate RGB reference inputs with 565/555/444
resolutions (optimal)
Master input Image
24 bpp
ARGB8888
Computation
Optimal Statistical
Color Quantization
2D IP & Verification
Environment
Golden Reference Image
565/555/444
format
565/555/444 RGB
Convert to ARGB888
Target IP Hardware
7. Generate RGB reference inputs with 565/555/444
resolutions (Initial)
Master input Image
24 bpp
ARGB8888
Computation
Color Quantization
And Dithering
(fast algorithms)
2D IP Verification Environment
Reference Image
565/555/444
format
565/555/444 RGB
Convert to ARGB888
Target IP Hardware
8. Output RGB color dithering for outputs with
565/555/444 resolutions
2D IP Verification Environment
ARGB8888
Computation
Color Quantization
And Dithering
(hardware)
Output Image
Derived from
565/555/444
format
565/555/444 RGB
Target IP Hardware
16. 16
Dithering: Algorithms, Quality Metrics
• Current implementation:
– Current implementation is ordered dither with 8x8 magic square matrix.
• Quality metrics to be used to evaluate dithering algorithms
and/or improvement:
– PSNR vs. original master 24bpp image + and visual quality.
– PSNR vs. Golden optimal color quantized reference image + visual qulity
