# US 7,746,395 B2 · Color interpolation methods for correcting outlying values

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- Number: US 7,746,395 B2
- Document ID: US7746395B2
- Status: Granted
- Kind: B2
- Application number: 11/644,385
- Filed: 2006-12-21
- Published: 2007-06-21
- Granted: 2010-06-29
- Earliest claimed: 2005-12-21
- Assignees: BYD Company Limited
- Inventors: Ziyu Zhu
- Web page: https://patentgrep.com/patent/US7746395B2

## CPC

- H04N 23/843: {Demosaicing, e.g. interpolating colour pixel values}
- G06T 3/4015: Image demosaicing, e.g. colour filter arrays [CFA] or Bayer patterns
- H04N 25/134: {based on three different wavelength filter elements}
- H04N 25/683: by defect estimation performed on the scene signal, e.g. real time or on the fly detection
- H04N 2209/046: Colour interpolation to calculate the missing colour values
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL

## Abstract

This invention of a color interpolation method for correcting color values of an image, comprising the steps of: constructing a color interpolation matrix having a plurality of points and a center point as an interpolation point, where each point being expressed by one known color and two unknown colors; correcting the known color value of the center point as a function of the color values of the center point and the points in the matrix having the same known color; choosing the horizontal direction or the vertical direction with respect to the center point as the benchmark direction for interpolation calculation; and interpolating one or more unknown color values of the center point as a function of the known color values of the points in the benchmark direction and the known color value of the center point.

## Claims

### Claim 1

A color interpolation method for correcting color values of an image, comprising the steps of:
constructing a color interpolation matrix having a plurality of points and a center point as an interpolation point, wherein each point being expressed by one known color and two unknown colors, wherein the known color of the center point being G;
correcting the known color value of the center point as a function of the known color value of the center point and the points in the matrix having the same known color;
correcting the value of known colors of the points surrounding the center point as a function of the two points with B as the known color and the two points with R as the known color; and
interpolating the two unknown color values of the center point as a function of the color values of the surrounding points with the known R or B colors and the known color value of the center point;
wherein for the two correcting steps, if the known color value of a certain point is larger than that of the surrounding points by a set value and the difference between the known color value and the average of the surrounding points' known color values is also larger than the set value, substituting the average value as the known color value of that certain point.

### Claim 2 (depends on 1)

The method of claim 1, wherein in the first correcting step, the average known color value of the eight points surrounding the center point having G as the known color, and in the second correcting step, for two points with R as the known color, the average value is R1=¼*(G33+G31+G22+G42) and Rr=¼*(G33+G35+G24+G44); and for two points with B as the known color, the average value method is Bu=¼*(G33+G13+G22+G24) and Bd=¼*(G33+G53+G42+G44).

### Claim 3 (depends on 2)

The method of claim 2, wherein in the interpolating step, further comprising the sub-steps of:
calculating the value of R in the center point: R33=½*(R32+R34)+¼*(G33−R1+G33−Rr);
calculating the value of B in the center point: B33=½*(B23+B43)+¼*(G33−Bu+G33−Bd);
Where:
R1=¼*(G33+G31+G22+G42);
Rr=¼*(G33+G35+G24+G44);
Bu=¼*(G33+G13+G22+G24); and
Bd=¼*(G33+G53+G42+G44); and
Where Rij, Gij and Bij are points with known color values from a 5×5 Bayer matrix, and 1<i and j≦5, with i and j being integers.