JPH03145380A - Automatic picture quality adjustor - Google Patents

Abstract

PURPOSE:To attain excellent automatic picture quality adjustment whose change in picture quality is not unnatural by making a rate of a change in a level of a video signal proper in the case of applying picture quality adjustment. CONSTITUTION:An automatic picture quality adjustment device 1 forms a video signal processing circuit of a television receiver 2 and a radio wave received by an antenna 3 is inputted to the input terminal and tuned by a tuner 4 and video intermediate frequency amplification and video detection are applied by a video intermediate frequency circuit 5 to form a video signal and the video signal is applied as an input video signal. Then a control means 11 of the device 1 controls a level conversion circuit 6 so as to increase the rate of change in the level of the input video signal subject to level conversion in response to the quantity between an objective level set by an objective level setting means 10 and a level detected by a level detection means 9. Thus, the automatic picture quality adjustment whose change in the picture quality is not unnatural is realized.

Description

[Detailed Description of the Invention] A. Industrial Field of Application The present invention relates to an automatic video quality adjustment device used in television receivers, etc., which adjusts the brightness and contrast of the video by increasing or decreasing the level of the video signal depending on the video. This invention relates to automatic adjustment of image quality such as color density and tone.

B1 Summary of the Invention The present invention is an automatic video quality adjustment device that automatically adjusts image quality such as brightness, contrast, color saturation, and tone. When performing level conversion processing for image quality adjustment on the input video signal so as to bring the level of the input video signal closer to the target level, (1) converting the level of the input video signal according to the magnitude of the difference to the target level; Control to increase or decrease the rate (
2) By controlling the rate of change when increasing and decreasing the level of the input video signal, the temporal response is optimized, and changes in image quality due to automatic video quality adjustment do not look unnatural. It is intended to do so.

C8 Prior Art In general, video signal processing circuits in television receivers, monitor receivers, etc. are designed to reproduce colors correctly or in accordance with the user's preferences. An image quality adjustment device is used to adjust image quality such as brightness, contrast, color depth, and two-tone tone.

The above-mentioned image adjustment device adjusts the image quality by subjecting the input video signal to a level conversion process that appropriately increases or decreases the level of the video signal related to image quality such as brightness and contrast.

Problems to be solved by the D9 invention In the past, many of these image quality adjustment devices adjusted the level of the input video signal to a level set by the user using an operation switch or the like or to a standard level predetermined by the manufacturer. . However, in reality, the level of the video signal at which the image quality is perceived as the best differs depending on the type of video and the scene. Therefore, we analyze the video by detecting the level of the video signal in short time units of several frames.
An automatic image quality adjustment device has been proposed that adjusts the image quality almost in real time so that the image quality is the best.

However, when performing such real-time image quality adjustment using an automatic video quality adjustment device, the level of the video signal is changed by a certain percentage at regular intervals in response to changes in the image, just like a general control circuit. If you do so, the change in image quality due to automatic video quality adjustment may look unnatural and create a sense of discomfort. That is, changes in image quality may be noticeable, or image quality adjustment may not be able to keep up with video switching.

In order to eliminate such drawbacks, the present invention aims to achieve good automatic video quality by optimizing the rate of change in the level of the video signal when performing image quality adjustment so that changes in image quality do not appear unnatural. The purpose is to provide an automatic video quality adjustment device that realizes adjustment.

Means for Solving the Problems In order to achieve the above-mentioned object, an automatic video quality adjustment device according to the present invention performs a level conversion process that performs level conversion processing for image quality adjustment on an input video signal to form an output video signal. means, and level detection means for detecting the level of the input video signal;
a target level setting means for setting a target level for level conversion by the level converting means according to the level of the input video signal detected by the level detecting means; a target level set by the target level setting means and the above level; and control means for forming a control signal according to the difference between the level detected by the detection means and controlling the conversion operation of the level conversion means using this control signal.

The control means of the automatic video quality adjustment device according to the first invention performs the level conversion according to the magnitude of the difference between the target level set by the target level setting means and the level detected by the level detection means. Control is performed to increase or decrease the rate of change in the level of the input video signal whose level is converted by the means.

Further, the control means of the automatic video quality adjustment device according to the second invention is such that the rate of change when increasing the level of the input video signal by the level converting means is different from the rate of change when decreasing the level. Take control.

F8 Effect The automatic video quality adjustment device according to the present invention converts the level of the input video signal using the level conversion means to form an output video signal that has been subjected to image quality adjustment. The conversion operation at this time is controlled by a control signal formed as follows.

That is, first, the level detection means detects the level of the input video signal, and the target level setting means sets a target level at which the detected level provides an appropriate image quality. Then, the control means generates a control signal corresponding to the difference between the target level set by the target level setting means and the level detected by the level detection means.

In the control means of the automatic video quality adjustment device according to the first invention, the control means adjusts the level according to the magnitude of the difference between the target level set by the target level setting means and the level detected by the level detection means. Control is performed to increase or decrease the rate of change in the level of the input video signal whose level is converted by the conversion means.

Further, the control means of the automatic video quality adjustment device according to the second invention performs control in which the rate of change when increasing the level of the input video signal is different from the rate of change when decreasing the level.

G. Embodiment Hereinafter, an embodiment in which the present invention is applied to a part of a video signal processing circuit of a television receiver will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an automatic video quality adjustment device 1 of this embodiment.

As described above, this automatic video quality adjustment device 1 constitutes a video signal processing circuit of a television receiver 2, and at its input terminal, radio waves received by an antenna 3 are tuned by a tuner 4, and further A video intermediate frequency circuit 5 performs video intermediate frequency amplification and video detection to produce a video signal, and this video signal is supplied as an input video signal.

This automatic quality adjustment device l includes a level conversion circuit 6 analog/digital (A/D) converter 7. It consists of a microcomputer 8. The level conversion circuit 6 and the A/D converter 7 are supplied with an input video signal from the video intermediate frequency circuit 5. The A/D converter 7 samples the input video signal in response to a sampling signal from the microcomputer 8, and sends the sampling data of the input video signal to the microcomputer 8. The microcomputer 8 includes level detection means 9. Target level setting means 10 controls A control signal is formed based on the level data from the A/D converter 7, and the level conversion circuit 6 is controlled by this control signal. The level conversion circuit 6 converts the level of the input video signal from the video intermediate frequency circuit 5 under the control of the microcomputer 8 to adjust the brightness. An output video signal with adjusted image quality such as contrast color depth and two-color tone is formed. The output video signal formed by the level conversion circuit 6 is sent from the automatic video quality adjustment device 1 to the picture tube 12 and displayed as a video.

Further, a setting circuit 13 consisting of a microcomputer is connected to the automatic quality adjustment device 1 and the tuner 4, and a remote controller 14 and a group of operation keys 15 are connected to the automatic quality adjustment device 1 and the tuner 4.
The setting circuit 13 respectively provides channel selection instruction information and image quality adjustment instruction information instructed by the user through manual operation.

Next, the operation of each part of the automatic image quality adjustment device 1 will be described in detail.

The A/D converter 7 is supplied with a sampling signal having different phases for the odd and even fields of the input video signal from the microcomputer B as a signal instructing the sampling timing. Such a sampling signal is generated by the sampling signal generating means 16 of the microcomputer 8. The processing for forming this sampling signal will be explained according to the flowchart of FIG.

The sampling signal forming process shown in this flowchart uses an H counter that counts the number of lines in the L field and an S counter that counts the number of samplings in one line (one horizontal opening period), starting from step S1. An odd field sampling signal is formed through the processing up to Sll, and steps S12 to S322
The processing up to this point forms an even field sampling signal.

That is, when processing starts at the beginning of a frame of a video signal, the value of the H counter is set to 0 in step S1, and then the value of N is
When the vertical synchronizing pulse is detected (YES), it is assumed that an odd field has started and the process proceeds to step S3. Then, in this step S3, the system waits in a loop of No until a horizontal synchronizing pulse is detected, and when the horizontal synchronizing pulse is detected (YES), the process proceeds to step S4, and after setting the S counter to O, the horizontal synchronizing pulse is detected. The process waits through a NO loop in step S5 until a predetermined time α has elapsed since the detection. When the time α has elapsed since the horizontal synchronization pulse was detected, the process proceeds to step S6, where one pulse of the sampling signal is output, and in the next step S7, 1 is added to the value of the S counter to output the sampling signal. The process waits through a NO loop in step S8 until a predetermined period of time has elapsed since one pulse was output. When this time period has elapsed since the output of one pulse of the sampling signal, the process proceeds to step S9, and it is determined whether the value of the S counter is equal to the predetermined number of samples n in one line, and if it is less than n (NO). Then, the operations from step S6 to step S9 are repeated. As a result, the sampling signal can be obtained one pulse at a time at a predetermined period t until the value of the S counter reaches n.

When the value of the S counter reaches n (YES) in step S9, it is assumed that all sampling within one line has been completed, and the process proceeds to step S10. After adding 1 to the value of the H counter in this step S10, in the next step 311, the value of the H counter reaches a predetermined number of lines m within one field (for example, the number of effective scanning lines displayed on the screen). Determine whether they are equal. If the value of this H counter is less than m (No), step S
3, and repeat the operations from step S3 to step Sll. As a result, in the odd field of the input video signal, as shown by A in Fig. 3, a sampling signal with a predetermined period whose phase is delayed by α from the horizontal synchronizing pulse is generated every 1 horizontal opening period (IH) by n pulses horizontally. Obtained over the sync period.

After completing the processing of the odd field, the value of the H counter becomes m (YES) in step Sll.
) and the process advances to the next step S12.

Each step from step S12 to step S22 is configured to perform the same processing as each step from step S1 to step Sll described above. However, in step 516, which corresponds to step S5 in which the elapsed time from the horizontal synchronization pulse is determined, the predetermined time is set not to the time α but to a predetermined time β different from this time α (for example β=α+t'+A). There is. As a result, in the even field of the input video signal, the 31st
As shown by B in FIG. 2, a sampling signal having a phase different from the sampling signal of the odd field, that is, a sampling signal of a predetermined period t whose phase is delayed by β from the horizontal synchronizing pulse, continues for one horizontal opening period ( IH) is obtained by n pulses each over m horizontal synchronization periods.

After processing the even field following the odd field, the value of the H counter becomes m in step S22 corresponding to step S11 (YES).
), and the process starts again from step S1 in the next frame.

The sampling signal formed by such processing is
The signal is applied to the A/D converter 7. The above A/D converter 7
samples the input video signal in accordance with this sampling signal. As a result, the A/D converter 7 obtains the sampling data of the input video signal sampled at the position indicated by the circle in the fourth area in the odd field, and the sampling data of the input video signal sampled at the position indicated by the circle in the fourth area is obtained from the A/D converter 7. Sampling data of the input video signal sampled at the positions indicated by x in the figure is obtained.

The sampling data formed by the A/D converter 7 is sent to the level detection means 9 of the microcomputer 8. This level detection means 9 is connected to the A/D converter 7.
The sampling data of the odd and even fields supplied from the field are combined to form a set of sampling output data for the l field. Then, by averaging this sampling output data for the entire screen and detecting the level, average level data of the screen indicated by the input video signal is formed.

In this way, by shifting the sampling position of the input video signal for each field and composing the sampled data for each frame, it is possible to avoid repeatedly sampling the same position with strong field correlation. . Therefore, if we consider one frame as a unit, compared to sampling the same position in each field, we can obtain sampling data with the same precision (resolution) as sampling twice as many sampling positions with the same number of samples. .

Note that such a correlation also exists between frames, so the same effect can be obtained even if the input video signal is sampled by shifting the sampling position every several frames (for example, every 1 frame).

The average level data of the input video signal formed by the level detecting means 9 is supplied to the target level setting means 10. This target level setting means 10 adjusts the brightness,
The target level of the level conversion by the level conversion circuit 6 is set so that the image quality such as contrast, color tone, etc. is the best.

At this time, the level conversion means 9 converts the setting circuit 13 into
The setting range of the target level is limited as follows, for example, based on the image quality adjustment information supplied from. That is, for example, regarding contrast, the fifth
As shown in the figure, when the user
The maximum level (
100'1), the target level can be set from the minimum level (Ox) to the maximum level (100x). However, when the user reaches the minimum level (0χ
), the target level above is up to 50.
It can only be set up to χ. By making the setting range of the target level change in accordance with the user's setting level, for example, if a user prefers images with low contrast, the contrast will be lowered even during automatic adjustment. The image quality can be automatically adjusted to reflect the user's preferences. Further, the level conversion means 9 is configured to limit other setting ranges based on the image quality adjustment information supplied from the setting circuit 13.

That is, as shown in FIG. When the contrast is set to the minimum level (0x), the brightness is set between the maximum level (1002) and 20x. By changing multiple target levels according to the level set by the user, for example, it is possible to prevent dark blurring when the contrast is strong, and to adjust the optimal brightness according to the degree of contrast. will be selected.

The process of setting target levels for contrast and brightness will be explained with reference to the flowchart of FIG. 6.

That is, the contrast value designated by the user is read in step T1. Then, in step T2, it is determined whether the value is 70% or more, and if the value is 70% or more (YES), the process proceeds to step T3, where the maximum contrast value is set to 100X (no limit) and the brightness is Set the minimum value to 60%. Also, the above value is 70%
If it is less than 50% (No), the process proceeds to step T4 and it is determined whether the above value is 50% or more. If this value is 50% or more (YES), the process proceeds to step T5, where the maximum value of contrast is set to 90% and the minimum value of brightness is set to 50%. Furthermore, if the above value is less than 50% (NO), the process proceeds to step T6 and the above value is 40%.
Decide if it is more than that. And if this value is 40% or more (
If YES), proceed to step T7 and set the maximum value of contrast to 70% and the minimum value of brightness to 30%.
Set to . Also, if the above value is less than 40% (NO)
, proceed to step T8 and set the maximum contrast value to 50.
% and set the minimum brightness value to 20%. Then, each step T3. T5. T7. Proceeding from step T8 to step T9, target levels for contrast and brightness are set.

In this manner, the target level setting means 10 sets the target level for level conversion by the level conversion circuit 6 so as to obtain the best image quality for each of the brightness, contrast, color depth, and tone.

The target level set by the target level setting means 10 is sent to the control means 11. This control means 11 forms a control signal for the level conversion circuit 6 based on the target level. The process of forming this control signal will be explained according to the flowchart of FIG.

The control signal forming process shown in this flowchart is related to the brightness of the video signal, and is performed in the following manner, with a predetermined minute level difference defined as one step, and each step as a unit.

In step U1, the level detecting means 9 performs the processing to detect the level of the input video signal (hereinafter referred to as the current level), and the process proceeds to the next step U2. In this step υ2, the process of the target level setting means 10 is performed to set a target level based on the current level, and the process proceeds to the next step U3. In step U3, the difference between the current level and the target level is determined, and in the next step U4, it is determined whether the difference is positive or negative.

If the above difference is positive (YES), step U5 determines whether the difference is within +10 steps, and if it is within +20 steps (YES), proceed to step U6 and 200m5.
ec is set to change at a rate of +1 step, and if the difference is +10 steps or more (NO), the process advances to step U7 and it is determined whether the difference is within +30 steps. If the above difference is within +30 steps at step U7 (YES), proceed to step U8 and 100m5e.
Set the interval to change at a rate of +1 step, and
If it is 30 steps or more (NO), the process proceeds to step U9 and it is determined whether the difference is within +40 steps. If the above difference is within +40 steps in this step U9 (YES)
If it is +40 or more (No), proceed to step UtO and set to change at a rate of +2 steps during roomsec.

Conversely, if the difference is negative in step U4 (NO), step 013. At U14 and U15, it is determined whether the above difference is within -10 steps, -30 steps, or -40 steps, and if the difference is within 110 steps, the process advances to step U16 and -I step is performed within 200 m5ec. If the above difference is within -30 steps, proceed to step U17 and set to change at a rate of 11 steps during roomsec, and if the above difference is within -40 steps, proceed to step U17. Proceed to step U1B and set to change at a rate of 12 steps per 100m5ec. If the above difference is -40 steps or more, proceed to step U19 and set to change at a rate of 14 steps per 100m5ec. .

Then, in step U19, each of the above steps U6. U
8. UIO, Ull, U15. U16U17. A control signal is formed so as to change the current level by the number of steps set in any step of U18.

By performing such control on brightness, the 8th
As shown in the figure, the difference between the target level and the current level is, for example, within ±10 steps or ±2020 steps.
When it is small, it is made to change slowly and in small steps at a rate of +1 step every 200 or 100 m5ec. Further, when the difference between the target level and the current level is large, for example, ±3030 steps 91 or ±4040 steps 21, the level is quickly and significantly changed at a rate of ±2 or 4 steps per 1°Qmsec. Further, the control means 11 performs similar processing regarding color density.

Furthermore, in this control means 11, as shown in FIG. 9, when the difference between the target level and the current level is from O step to +50 steps, the contrast is slowly and slightly reduced at a rate of +1 step over 100 m5ec. If the above-mentioned difference is larger than that, it is changed quickly and significantly at a rate of +8 steps per 100 m5ec. Also, if the difference between the target level and the current level is, for example, from O step to 110 steps, 100
Make small changes slowly at a rate of 12 steps per m5ec, and if the above difference is greater than 100m.
Rapidly and significantly changes at a rate of 16 steps in 5 ec.

The level conversion circuit 6 converts the level of the input video signal from the intermediate frequency circuit 5 in accordance with the control of the control means 11, thereby forming an output video signal with adjusted image quality and receiving the image. It is designed to be sent to pipe 12.

As described above, in this automatic video quality adjustment device 1, when the control means 11 forms a control signal, for example, regarding brightness and color density, when the difference between the target level and the current level is small, the control signal is slowly adjusted in small steps. When the difference is large, the difference is made to change quickly and significantly. Therefore, it is possible to make changes in image quality invisible when the images are similar, and to quickly respond to changes in images.

Further, for example, regarding the contrast, the value is changed slowly when the value is increased and quickly when the value is decreased depending on the difference between the target level and the current level. By performing such control on the contrast, it is possible to make darkening or the like when the image suddenly becomes dark, for example, less noticeable.

H1 Effects of the Invention In the automatic video quality adjustment device according to the present invention, the level detection means detects the level of the input video signal, and the target level setting means sets a target level that provides appropriate image quality at the detected level. Then, the control means generates a control signal according to the difference between this target level and the level detected by the level detection means, and the level conversion means is controlled by this control signal, and the input video signal is added to the input video signal for image quality adjustment. I am trying to perform level conversion processing. Therefore, this automatic video quality 5-cycle adjustment device can perform image quality adjustment on input video signals almost in real time, and can form output video signals with the best image quality depending on the type of video and scene. be.

In the automatic video quality adjustment device according to the first aspect of the invention, when the control means forms the control signal, the difference between the target level set by the target level setting means and the level detected by the level detection means is determined. The rate of change in the level of the input video signal to be level-converted by the level converting means is controlled to be large or small depending on the level. For example, by performing such control on brightness and color density, changes in image quality will not be noticeable when the images are similar, and it will be possible to quickly respond to changes in images.

Further, in the automatic video quality adjustment device according to the second invention, when the control signal is formed by the control means, the rate of change when increasing the level of the input video signal is different from the rate of change when decreasing the level. to exercise control.

For example, by performing such control on the contrast, it is possible to make dark spots and the like when the image becomes dark, such as an elephant, less noticeable.

Therefore, the automatic video quality adjustment device according to the present invention can appropriately adjust the rate of change in the level of the video signal when performing image quality adjustment, and can realize good automatic video quality adjustment so that changes in image quality do not appear unnatural.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an automatic video quality adjustment device according to the present invention applied to a television receiver, FIG. 2 is a flowchart of a sampling signal forming process of the level detection means used in the automatic adjustment device, and FIG. 3 is a time chart of the above-mentioned sampling signal, Fig. 4 is a schematic diagram for explaining the sampling position when the input video signal is sampled by the above-mentioned sampling signal, and Fig. 5 is a diagram of the target level setting means used in the above-mentioned automatic adjustment device. Graphs for explaining the processing, FIG. 6 is a flowchart of the processing of the target level setting means, FIG. 7 is a flowchart of the processing of the control means used in the automatic adjustment device, and FIG. 8 is the brightness of the control means. FIG. 9 is a schematic diagram for explaining the contrast-related processing of the control means. ■...Automatic quality adjustment device 2...Television receiver 6...Level conversion circuit 7...A/D converter 8...Microcomputer 9...Level detection means lO...Target Level setting means 11...control means 10r〉7〉100m range for the first paddle level Figure 5

Claims (2)

[Claims] (1) Level conversion means for performing level conversion processing on the input video signal for image quality adjustment to form an output video signal; Level detection means for detecting the level of the input video signal; and Level detection means for detecting the level of the input video signal; a target level setting means for setting a target level for level conversion by the level converting means according to the level of an input video signal; and a target level set by the target level setting means and a level detected by the level detecting means. control means for forming a control signal corresponding to the difference between the target level set by the target level setting means and the level converting means for controlling the conversion operation of the level converting means using the control signal; An automatic video quality adjustment device, characterized in that the rate of change in the level of the input video signal whose level is converted by the level converting device is controlled to be large or small depending on the magnitude of the difference between the level and the level detected by the level detecting device. (2) level conversion means for performing level conversion processing for image quality adjustment on the input video signal to form an output video signal; level detection means for detecting the level of the input video signal; and a level detection means for detecting the level of the input video signal; a target level setting means for setting a target level for level conversion by the level converting means according to the level of an input video signal; and a target level set by the target level setting means and a level detected by the level detecting means. and control means for forming a control signal according to the difference between the two and controlling the conversion operation of the level conversion means using the control signal, the control means increasing the level of the input video signal by the level conversion means. An automatic video quality adjustment device characterized in that the rate of change when the level is decreased is different from the rate of change when the level is decreased.