JP3018612B2 - Single-chip color camera and color signal processing circuit used therefor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-chip color camera and
More particularly, the present invention relates to a single-chip color camera configured to derive both a still image output and a moving image output, and a color signal processing circuit used for the same.

[0002]

2. Description of the Related Art There is known a color signal processing circuit of an image pickup apparatus such as a single-chip color camera which is configured to derive a still image output and a moving image output (for example,
See JP-A-63-31377).

A moving image output of an image pickup apparatus such as a single-chip color camera is a video signal based on a television signal format, whereas a still image output is used for hard copy or the like. It is required that the video signal be as wide as possible without being limited by the above.

[0004]

2. Description of the Related Art FIG. 5 is a block diagram showing a conventional example of a color signal processing circuit configured to be able to simultaneously derive a still image output and a moving image output. In the figure, R (red), G (green), and B separated from the imaging output by the primary color separation circuit 4 are shown.
The three primary color signals (blue) are the white balance amplifier 5
After passing through R, 5G, and 5B, signal processing is performed in two systems, one for still images and the other for moving images.

That is, the white balance amplifier 5R,
The three primary color signals having passed through 5G and 5B pass through a wideband low-pass filter (LPF) 6 and a narrow-band low-pass filter 9 ', respectively, and are then supplied to color difference matrix circuits 8S and 8M via gamma correction circuits 7S and 7M. Are converted into color difference signals (RY) and (BY) and are derived as a still image output and a moving image output, respectively.

[0006]

However, the conventional color signal processing circuit requires a white balance amplifier 5R,
Since two systems of circuits are required for signal processing of 5G and 5B and thereafter, there is a disadvantage that the circuit scale becomes large and the circuit configuration becomes complicated.

Accordingly, the present invention is to provide a single-chip color camera capable of deriving both a still image output and a moving image output with a simple circuit configuration and a color signal processing circuit used therefor by reducing the circuit scale. Aim.

[0008]

DISCLOSURE OF THE INVENTION Single-plate collar according to the present invention
The camera includes a solid-state imaging device and an imaging output of the solid-state imaging device.
A primary color separation circuit for separating the three primary color signals from
Signal processing for three primary color signals
The signal processing circuit to make up and the three primary color signals passed through this signal processing circuit
Color difference which is converted to color difference signal and derived as still image output
Matrix circuit and color difference by this color difference matrix circuit
Deriving as video output by passing the low-frequency component of the signal
The configuration includes a narrow-band low-pass filter.

A color signal processing circuit for a single-chip color camera according to the present invention includes a primary-color separation circuit for separating three primary-color signals from an imaging output of the single-chip color camera, and a signal processing for the three primary-color signals by using a wideband low-pass filter. A signal processing circuit to be formed, a color difference matrix circuit that converts the three primary color signals passed through the signal processing circuit into color difference signals and derives them as a still image output, and passes a low-frequency component of the color difference signals by the color difference matrix circuit to output a moving image And a narrow-band low-pass filter derived as follows.

[0010]

In the single-chip color camera and the color signal processing circuit used therein, the three primary color signals after the primary color separation are
After signal processing by a signal processing system including a wideband low-pass filter and conversion into a color-difference signal, the color-difference signal is directly derived as a still image output, and is also derived as a moving image output through a narrow-band low-pass filter. Only one signal processing system for signals is required, and the circuit configuration can be simplified.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, a solid-state image sensor, for example, CC
On the D image sensor 1, for example, G (green),
A color filter array 2 in which Ye (yellow) and Cy (cyan) colors are coded as shown in FIG. 2 is provided.

The imaging output of the CCD image sensor 1 is S
The signal is supplied to a primary color separation circuit 4 via a / H (sample / hold) circuit 3 and separated into three primary color signals of R, G, and B.
These three primary color signals are supplied to white balance amplifiers 5R and 5R.
After the white balance is adjusted in G and 5B, the signal is supplied to the γ correction circuit 7 via the wideband low-pass filter 6 to perform color signal processing.

In this color signal processing, the gamma correction circuit 7
Is performed, but in order to prevent aliasing from a high frequency band when the nonlinear processing is performed, a wideband low-pass filter 6 is disposed in front of the γ correction circuit 7. That is, under the coding example of FIG. 2, the primary color separation formula is R = Ye-G, B = Cy-G, G = G, and shows the S / H output (a) and the primary color separation output (b). In FIG. 3, as is apparent from FIG. 3B, a signal below black is generated, and since only the signal above black is handled in the γ correction, a low-pass filter that satisfies R = Ye + (− G) is required. It becomes.

The γ-corrected three primary color signals are supplied to a color difference matrix circuit 8 and converted into color difference signals (RY) and (BY). These color difference signals (RY) and (BY)
Is output as a moving image output through a narrow band low-pass filter 9 and is output as a still image output through a delay circuit 10. That is, a moving image output and a still image output can be derived simultaneously.

As an example of the narrow-band low-pass filter 9, as shown in FIG. 4, while the cut-off frequency f _CW of the wide-band low-pass filter 6 is about 2 MHz, the cut-off frequency f _CN is 1 MHz. A material having a frequency characteristic of such a degree is used. As a result, a still image output having a wide band which is not restricted by the television signal format can be obtained.

The delay circuit 10 provided for the still image output is for compensating the delay time in the narrow band low-pass filter 9 for the moving image output, and is not essential. If the timing between the output of the moving images is not taken into consideration, it may be omitted.

In the above embodiment, the still image output and the moving image output are derived at the same time. However, it is not always necessary to derive the still image output and the moving image output at the same time. Is also possible.

[0018]

As described above in detail, according to the present invention, the three primary color signals after the primary color separation are subjected to signal processing by a signal processing system including a wide band low-pass filter and converted into color difference signals. The signal is directly derived as a still image output and is also derived as a moving image output through a narrow-band low-pass filter, so that a signal processing system (γ correction circuit, color difference matrix circuit) for three primary color signals is provided in one system. Thus, since the circuit scale can be reduced, there is an effect that the circuit configuration can be simplified.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a coding diagram of an example of a color filter array.

FIG. 3 is a waveform diagram of an S / H output (a) and a primary color separation output (b).

FIG. 4 is a frequency characteristic diagram of a broadband low-pass filter and a narrow-band low-pass filter.

FIG. 5 is a block diagram showing a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 CCD image sensor 2 color filter array 4 Primary color separation circuit 5R, 5G, 5B White balance amplifier 6 Broadband low-pass filter 7, 7S, 7M γ correction circuit 8, 8S, 8M Color difference matrix circuit 9, 9 'Narrow band low-pass filter

Claims (2)

(57) [Claims] A solid-state imaging device; a primary color separation circuit for separating three primary color signals from an imaging output of the solid-state imaging device; a signal processing circuit having a wideband low-pass filter to perform signal processing on the three primary color signals; A color difference matrix circuit that converts the three primary color signals that have passed through the signal processing circuit into color difference signals and derives them as a still image output; A single-chip color camera comprising a filter. 2. A primary color separation circuit for separating three primary color signals from an imaging output of a single-chip color camera; a signal processing circuit having a wideband low-pass filter for performing signal processing on the three primary color signals; A color difference matrix circuit that converts the three primary color signals that have passed through to color difference signals and derives it as a still image output; A color signal processing circuit for a color camera.