# US 7,609,424 B2 · Circuit of scanner to perform color space conversion on RGB signal

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- Number: US 7,609,424 B2
- Document ID: US7609424B2
- Status: Granted
- Kind: B2
- Application number: 10/034,860
- Filed: 2001-12-27
- Published: 2003-02-20
- Granted: 2009-10-27
- Earliest claimed: 2001-12-27
- Inventors: Chun-Jen Chen; Shih-Huang Chen
- Web page: https://patentgrep.com/patent/US7609424B2

## CPC

- H04N 1/40012: {Conversion of colour to monochrome}
- H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION

## Abstract

A circuit of a scanner to perform a color space conversion on an RGB signal. The circuit has several sampling-amplified-offset devices to sample, amplify and compensate potential of an R charge signal, a G charge signal and a B charge signal to obtain an R analog signal, a G analog signal and a B analog signal. The circuit further has a gain adder to multiply the corresponding weighted gain with the R analog signal, the G analog signal and the B analog signal. The multiplication results are then summed up to obtain an addition analog signal. A multiplexer is also included to select between the R analog signal, the G analog signal, the B analog signal and the addition analog signal for output.

## Claims

### Claim 1

A circuit, comprising:
a plurality of sampling-amplified-offset devices configured to sample, amplify, and compensate levels of an R charge signal, a G charge signal, and B analog signal, respectively, and obtain an R analog signal, a G analog signal, and a B analog signal;
a gain adder configured to multiply at least one of the R, G, or B analog signals by a corresponding weighted value, wherein the gain adder is further configured to add at least a subset of the analog signals that are multiplied by the weighted values to obtain an addition analog signal; and
a multiplexer configured to select at least one of the R analog signal, the G analog signal, the B analog signal, or the addition analog signal as an output signal;
wherein at least one of the sampling-amplified-offset devices includes:
a sampler configured to obtain a plurality of samples of at least one the R, G, or B charge signals and to determine a luminance based, at least in part, on a difference between at least two of the samples;
a programmable gain amplifier configured to obtain an amplified luminance according to a gain value; and
an offset device configured to compensate at least one of the R, G, or B analog signals, respectively, based, at least in part, on the obtained amplified luminance.

### Claim 2 (depends on 1)

The circuit of claim 1, wherein the gain adder comprises:
a plurality of gain amplifiers configured to multiply at least one the R analog signal, the G analog signal, or the B analog signal by the corresponding weighted values to obtain a plurality of weighted analog signals; and
an adder configured to add the weighted analog signals to obtain the addition analog signal.

### Claim 3 (depends on 1)

The circuit of claim 1, wherein the multiplexer is further configured to select at least one of the R, G, or B analog signals and output the selected one to an analog-digital converter.

### Claim 4

A circuit, comprising:
a plurality of sampling-amplified-offset devices configured to sample, amplify, and compensate levels of an R charge signal, a G charge signal, and a G charge signal, and a B charge signal, respectively, and obtain an R analog signal, a G analog signal, and a B analog signal;
a gain adder configured to multiply at least one of the R,G, or B analog signals by a corresponding weighted value, wherein the gain adder is further configured to add at least a subset of the analog signals that are multiplied by the weighted values to obtain an addition analog signal; and
a multiplier configured to select at least of the R analog signal, the B analog signal, or the addition analog signal as an output signal;
wherein at least one of the sampling-amplified-offset devices includes:
a sampler configured to obtain a plurality of samples of at least one of the R, G, or B charge signals and to obtain an luminance;
an offset device configured to compensate a level of the luminance to obtain a compensated luminance; and
a programmable gain amplifier configured to adjust a gain value to amplify the compensated luminance and to obtain at least one of the R, G, or B analog signals.

### Claim 5 (depends on 4)

The circuit of claim 4, wherein the gain adder comprises:
a plurality of gain amplifiers configured to multiply at least one of the R analog signal, the G analog signal, or the B analog signal by the corresponding weighted values to obtain a plurality of weighted analog signals; and
an adder configured to add the weighted analog signals to obtain the addition analog signal.

### Claim 6 (depends on 4)

The circuit of claim 4, wherein the multiplexer is further configured to select at least one of the R, G, or B analog signals and output the selected one to an analog-digital converter.

### Claim 7

A circuit, comprising:
a plurality of sampling-offset devices configured to sample, amplify, and compensate levels of an R charge signal, a G charge signal, and a B charge signal, respectively, and obtain an R analog signal, a G analog signal, and a B analog signal;
a plurality of gain adders configured to multiply the R, G, and B analog signals by different weighted values to obtain a plurality or results, wherein the plurality of gain adders are further configured to add at least a subset of the results, into an addition analog signal; and
a multiplexer configured to select the R analog signal, the G analog signal, the B analog signal, or the addition analog signal as an output;
wherein at least one of the sampling-amplified-offset devices includes:
a sampler configured to perform sampling at least twice on the R, G, or B charge signals and to perform a subtraction operation on sampling results to obtain a luminance;
a programmable gain amplifier configured to adjust a gain value to amplify the luminance and to obtain an amplified luminance according to the gain value; and
an offset device configured to compensate the amplified luminance to obtain the R, G, or B analog signal.

### Claim 8 (depends on 7)

The circuit of claim 7, wherein at least one of the gain adders comprises:
a plurality of gain amplifiers configured to multiply the R analog signal, the G analog signal, and the B analog signal by the corresponding weighted values to obtain a plurality of weighted analog signals; and
an adder configured to add the weighted analog signals to obtain the addition analog signal.

### Claim 9 (depends on 7)

The circuit of claim 7, wherein claim is further configured to select at least one of the R, G, or B analog signals and output the selected one to an analog-digital converter to form a digital signal.

### Claim 10

A circuit, comprising:
a plurality of sampling-amplified-offset devices configured to sample, amplify, and compensate levels of an R charge signal, G charge signal, and a B charge signal, respectively, and obtain an R analog signal, a G analog signal, and a B analog signal;
a plurality of gain adders configured to multiply the R, G, and B analog signals by different weighted values to obtain a plurality of results, wherein the plurality of gain adders are further configured to add at least a subset of the results into an addition analog signal; and
a multiplexer configured to select the R analog signal, the G analog signal, the B analog signal, or the addition analog signal as an output;
wherein at least one of the sampling-amplified-offset devices includes:
a sampler configured to perform sampling at least twice on the R, G, or B charge signal and to perform a subtraction operation on sampling results to obtain a luminance;
an offset device configured to compensate a level of the luminance to a compensated luminance; and
a programmable gain amplifier configured to adjust a gain value to amplify the compensated luminance and to obtain the R, G, or B analog signal.

### Claim 11 (depends on 10)

The circuit of claim 10, wherein one or more of the gain adders comprises:
a plurality of gain amplifiers configured to multiply the R analog signal, the G analog signal, and the B analog signal by the corresponding weighted values to obtain a plurality of weighted analog signals; and
an adder configured to add the weighted analog signals to obtain the addition analog signal.

### Claim 12 (depends on 10)

The circuit of claim 10, wherein the multiplexer is further configured to select at least one of the R, G, or B analog signals and output the selected one to an analog-digital converter to form a digital signal.