1. How to Digitize the Natural Color
Tiffany Shih, Fang-chi Lu Computer Science and Information Engineering, National Chung Cheng University, 2018
Introduction
Recently, how to convert the analog signals in nature to digital signals efficiently and precisely is an important issue.
In this poster, we introduce a technology, which is commonly used in cameras, camcorders, and scanners, can use RGB color model to create a color image we saw from the nature.
Examples
Step 2. Bayer Color Filter
The interpolation algorithm for deriving the two missing color channels at each photo-site is called demosaicing.
Algorithm
Nearest neighbor
Linear
Cubic
Cubic spline
Step 3. Demosaicing
Figure 5. The actual color
Figure 4. Bayer Color Filter
Figure 2. Bayer Color Filter Q:
What are the R, G, B values for pixel A if nearest neighbor algorithm is applied?
Materials and methods
Step 1. Sampling & Quantization
In order for the machine to recognize the analog signal, we use a photosensitive element to project light on a plane, divide the plane into many small squares.
Each square is 1 pixel.
Figure 3. Demosaicing
Conclusions
Bayer-filter cameras can convert the analog signals in nature to digital signals. However, it has a feature that each pixel is filtered to record only one of three colors. Demosaicing algorithms can make each pixel including part of red, green, and blue values to obtain a accuracy image.
Acknowledgments
We thank the textbook of Chen-Kuo Chiang professor support.
A less expensive method of color detection uses an array to detect only one color component at each photosite.
Interpolation is then used to derive the other two color components based on information from neighboring sites.
A color filter array (CFA) is used for arranging RGB color filters on a square grid of photosensors.
Twice as many green sensors as blue or red sensors. Because the human eye is more sensitive to green.
Determining R or B from the center G photosite entails an average of two neighboring sites
Determining B from the center R photosite entails an average of four neighboring sites diagonal from R
Literature cited
RGB "Bayer" Color and MicroLenses
Chen-Kuo Chiang Professor textbook
Figure 1. Image Sampling & Quantization