JPS63234690A - Image pickup device - Google Patents

Abstract

PURPOSE:To improve picture quality by providing a correction circuit applying gammacorrection of an image pickup signal from an object and a changeover means switching the level of the gamma correction depending on the lightness of the object or color temperature. CONSTITUTION:The gamma correction circuits 5, 6 apply the gamma correction of a luminance signal (Y) and a chrominance signal (C). A changeover switch 7 provided as a switching means switching the level of the gamma correction depending on the lightness of an object or color temperature is switched manually indoor and outdoor and contacts of indoor and outdoor sides are connected to each connecting point of resistors R1-R3 connected in series with the DC power supply (voltage Vcc). Moreover, the color temperature filter is switched by the switch 7 or the adjustment of the color balance of the color signal system is switched so as to be matched to the state of indoor and outdoor. Thus, the gammacorrection level is switched in response to the pickup state of an object to improve the picture quality.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of use in the IT industry] The present invention relates to an imaging device that improves image quality through particularly appropriate γ (gamma) correction.

[Conventional technology]

In imaging devices such as color television cameras,
Light from a subject is input through the lens of an optical system and enters an imaging system including an image sensor, where it is photoelectrically converted and then sent to a signal processing circuit. Necessary signal processing is then performed in this signal processing circuit and output as a video signal to a monitor or the like. At that time, the imaging signal from the subject is γ
Although it is necessary to perform correction, this γ correction is normally performed in a signal processing circuit within the imaging device on the image sending side. Conventionally, the level of this γ correction is independent of the color temperature and brightness of the subject.
It remains constant.

[Problem that the invention seeks to solve]

However, in conventional imaging devices, the level of gamma correction is constant as described in ``2'', so for example, if the illuminance of the subject is significantly different between indoors and outdoors, the image quality is not satisfactory for both indoors and outdoors. There was a problem that it was not possible to obtain For example, outdoors, the brightness is higher than the color signal level, so there is a problem that the colors become lighter.

The present invention was made to eliminate such problems, and provides an imaging device that can switch the level of γ correction with a simple configuration and improves image quality.

[Means for solving problems]

The imaging device of the present invention includes a correction circuit that performs γ correction of an image signal from an object, and a switching means that switches the level of the γ correction in accordance with the brightness or color temperature of the object.

[Effect]

In the imaging apparatus of the present invention, the level of γ correction is switched by the switching means according to the brightness or color temperature of the subject, so a high-quality video signal can be obtained under any circumstances.

〔Example〕

FIG. 1 is a block diagram showing the circuit configuration of an embodiment of the present invention. In the figure, 1 is an optical system lens, 2 is an image sensor, 3 is an amplifier circuit, and 4 is an auto iris control (AE) circuit and an auto gain control (AGC).
Circuits 5 and 6 are γ correction circuits that perform γ correction on the image pickup signal from the subject that has passed through each of the circuits described above, and perform γ correction on the luminance signal (Y) and color signal (C), respectively. Reference numeral 7 denotes a changeover switch that is provided as a changeover means to change the level of γ correction according to the brightness or color temperature of the subject, and can be manually changed between indoors and outdoors (outdoors). The outer contacts each have a DC power supply (voltage V
cc) and the resistors R1+R2*R3 connected in series. Further, in accordance with this changeover switch 7, a color temperature filter (not shown) is changed over, and the color balance adjustment of the color signal system is changed over to suit indoors and outdoors, respectively. 8 is a modulation circuit that modulates the γ-corrected color signal, and 9 is a mixing circuit that mixes the modulated color signal and the γ-corrected luminance signal.

In the above configuration, what is the optical signal (imaging signal) from the subject? The light passes through the lens 1 and reaches the image sensor 2, where it is photoelectrically converted. The imaging signal converted into an electric signal is sent to the amplifier circuit 3.
After being amplified by the auto iris control and auto gain control circuit 4, the signal is input to the gamma correction circuits 5 and 6, where it is corrected to an appropriate gamma level. The γ-corrected color signal is input to a mixing circuit 9 via a modulation circuit 8, and the γ-corrected luminance signal is also input to the mixing circuit 9, from which a video signal is output. This video signal has a gamma correction level switched between indoors and outdoors by a manual changeover switch 7. Specifically, for example, indoors, γ at 5 and 6 is set to γ=0
．． 45, outdoor γ of 5 is γ = 0.5, γ of 6
The color is emphasized by setting γ=0.3. Therefore, appropriate γ correction is performed depending on the situation of the subject, resulting in improved image quality.

In other words, the illuminance and spectral characteristics of the subject differ significantly between indoor photography and outdoor photography, and it is not possible to obtain good image quality that satisfies both with the same luminance γ level and the same color γ level.Therefore, this implementation In the example, a changeover switch 7 for changing the level of γ correction is provided, and γ correction is performed according to each situation. Therefore, as described above, image quality can be significantly improved.

FIG. 2 is a block diagram showing another embodiment of the invention. In this embodiment, the gamma correction switching means is constructed of a sensor that detects the color temperature of the subject and a changeover switch that changes the gamma correction level based on the detection signal. That is, the color temperature of the subject changes with changes in illuminance, and this can be detected to automatically switch the level of γ correction. In the figure, reference numerals 10 and 11 denote an R sensor and a B sensor of a light receiving optical system separate from the imaging optical system, which detect the color temperature of an R (red) signal and a B (blue) signal, respectively. The detection signals of these sensors 10 and 11 are then sent to a logarithmic amplifier 1, respectively.
After being logarithmically amplified by 2.13, it is input to the subtraction circuit 14, where it is subtracted. This subtracted signal is further input to the comparator 15, where it is compared with a predetermined signal to determine whether it is indoors or outdoors.

Then, according to the judgment result, the changeover switch 1 is automatically set.
6 is switched, and the level of correction in each γ correction circuit 5.6 is switched so as to have the above-mentioned characteristics, that is, to emphasize colors outdoors.

Therefore, the image quality is significantly improved as in the above embodiment.

Note that in the above embodiment, the level of γ correction is switched in two steps for indoor and outdoor, but it is also possible to switch to a plurality of more steps, and the switching level can also be set arbitrarily. Furthermore, since the γ of the Y system and the C system are controlled separately on the Kinomoto side, it is easy to switch the color emphasis between outdoor and indoor.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to switch the level of γ correction depending on the shooting situation of the subject,
This has the effect of improving image quality.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing one embodiment of the invention, and FIG. 2 is a block diagram showing another embodiment of the invention. 5.6...γ (gamma) correction circuit 7.16...
...Selector switch 10...R sensor 11...B sensor

Claims (3)

[Claims] (1) An imaging device characterized by comprising a correction circuit that performs gamma correction of an imaging signal from an object, and a switching means that switches the level of gamma correction according to the brightness or color temperature of the object. (2) The imaging device according to claim 1, wherein the switching means is constituted by a switch that switches the gamma correction level between indoors and outdoors. (3) Imaging according to claim 1, characterized in that the switching means is constituted by a sensor that detects the color temperature of the subject and a switch that switches the level of gamma correction based on the detection signal. Device.