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发表于 2007-2-8 14:09:25
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Here are my experience for your reference.
1. The role of DSP/ISP in AWB, AE, AF is only to do statistic. Such as
a. AWB is used to do the average R, G, B value statistic. There are also dependent on
your algorithm. Currently the most algorithms are Gray World.
b. AE is used to do the average Y statistic. Many algorithm divide the image into many
segment and calculate the average Y in the image.
c. AF is used to do the focus value statistic. The focus value is calcuated by the
algorithm that can differentiate the high frequence signal.
So, DSP/ISP can do the statistic in many choice. Such as RGB Bayer raw data, RGB data .
etc. Even you get the raw data, you can know the statistic data.
2. But who do the real algorithm for AWB, AE, AF. This is what firmware do or what
the person develop the algorithm do. The developer accord those statistic data, and use those
statistic data to perform their algorithm. BTW, DSP/ISP is only used to perform the
statistic not algorithm, becasuse the statistic data can't be done by software.
3. What happen to the rawdata to LCD data ??
This should be dependent on the pipeline of the ISP vender. I give the most simple
pipeline for you reference
Sensor data --> black level correct --> Defective pixel correction --> Noise reduction
--> interpolate --> AE, AF, AWB --> Color correction ---> gamma --> YUV convert -->
edge enhancemnet --> downsampling --> output data format convert.
4. What is the real pipeline arragnement ? This is the know-how for each ISP vendor.
Good pipeline can lead to good image quality. |
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