JP2013066230A - Video signal processing apparatus and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce deterioration in image quality caused by influence of noise in a television video signal when applying progressive conversion processing or frame rate conversion processing so as to be consistent with a frame rate of the video signal.SOLUTION: A video signal processing apparatus detects whether or not an input video signal is a telecine-converted video signal and, in accordance with a result of the detection by telecine conversion signal detecting means, performs progressive conversion of the input video signal. Then, the apparatus detects a noise level of the input video signal and, if the noise level is higher than a predetermined level on the basis of a result of the detection, performs control to switch off the detection processing of the telecine conversion signal detecting means.

Description

  The present invention relates to a video signal processing device that performs processing such as progressive conversion on an interlaced video signal or the like that uses a movie film as a source, and an image display device equipped with such a video signal processing device.

  Currently, an IP conversion unit that progressively converts an interlace video signal in a television receiver or the like detects whether the source of the video signal is a movie film or a video camera, and performs IP conversion suitable for the source. Many functions that perform processing and display images with higher image quality are employed. Furthermore, recently, in the case of a video signal that is a movie film source (hereinafter also referred to as a film signal), a smoother motion of an image is obtained by performing a frame rate conversion process by motion compensation after the IP conversion process. Is realized. (For example, refer to Patent Document 1.)

  5 and 6 show a process for detecting a film signal. Of these, FIG. 5 shows a process for detecting a 2: 2 film signal subjected to a 2: 2 pull-down process for conversion into a 50 Hz PAL signal (576i). In a 2: 2 film signal, two fields are generated from the same frame by dividing one frame of film into an odd (even) field and an even (even) field. Therefore, if the difference for each field between the input signal and the signal obtained by delaying the input signal by one field is calculated, the difference between the same frames and the difference between different frames are calculated alternately. Since it changes alternately with 0, 1, 0, 1,..., It is detected that it is a 2: 2 film signal.

  FIG. 6 shows a process for detecting a 3: 2 film signal subjected to a 3: 2 pull-down process for conversion to a 60 Hz NTSC signal (480i). In a 3: 2 film signal, three fields are generated from the same frame, and then two fields are generated from the same frame alternately. Therefore, if the difference for each field between the input signal and the signal obtained by delaying the input signal by 2 fields is calculated, the difference between the same fields is calculated every 5 fields and the difference becomes 0. The signal is detected.

  FIG. 7 shows frame rate conversion processing by motion compensation, taking a 2: 2 film signal as an example. IP conversion processing (2: 2) for adding a 2: 2 film signal (50 Hz PAL signal (576i)) as shown in FIG. 7A to an Odd field and an Even field as shown in FIG. 7B. After being converted into a 25 Hz progressive signal by pull-down reverse processing), as shown in FIG. 7 (c), a motion vector is detected every other field, and an intermediate field is interpolated by motion compensation. Convert the frame rate to. This frame rate conversion makes the displayed image move smoothly.

JP 2004-343333 A

  However, when the film signal detection processing as shown in FIGS. 5 and 6 is performed in a state where the S / N ratio is deteriorated due to, for example, the electric field strength of the RF signal transmitted from the receiving antenna to the television receiving device weakening. When the difference is taken, since it is originally generated from the same frame, even if the field is supposed to be zero, a difference may occur due to the influence of random noise, which may cause a malfunction in detection. When such a malfunction occurs, the detection result of the film signal becomes unstable, and although it is a film signal, an IP conversion process for the film signal and a normal camera signal (video signal sourced from the video camera) Therefore, there is a problem that an image becomes unsightly.

  Further, when the film detection result becomes unstable as described above, the frame rate conversion process as shown in FIG. 7C is frequently switched between on and off, so that the image becomes more unsightly. Further, when the noise level becomes high, a malfunction occurs in the motion vector detection itself, so that an accurate vector cannot be detected, causing a problem that the screen is broken.

  In view of the above, the present invention matches the frame rate of a television video signal by arranging original images such as 2: 2 film signals and 2: 3 film signals based on a predetermined sequence. As described above (in this application, the original image is a movie, animation, or computer graphics, which will be referred to as “telecine conversion”), the video signal is subjected to progressive conversion processing and frame rate conversion processing. In this case, it is an object to improve the problem of image quality degradation due to the influence of noise in the video signal.

  In order to solve the above problems, a video signal processing apparatus according to the present invention includes a telecine conversion signal detection means for detecting whether or not an input video signal is a video signal subjected to telecine conversion, and detection by the telecine conversion signal detection means. An IP conversion unit that progressively converts the input video signal according to the result, a noise level detection unit that detects a noise level of the input video signal, and a noise level of a predetermined level or more based on a detection result of the noise level detection unit In the case of the level, a control means for turning off the detection processing of the telecine conversion signal detection means is provided.

  This video signal processing device performs progressive conversion processing on the input video signal according to the detection result of whether or not the input video signal is a telecine-converted video signal, but detects the noise level of the input video signal. If the noise level is high, the detection process of the telecine conversion signal detection means is turned off.

  As a result, when the noise level of the input video signal is large, the IP conversion means does not perform the progressive conversion process for the video signal subjected to telecine conversion. As a result, when the noise level of the input video signal is large, the progressive conversion process for the video signal telecine-converted due to the malfunction of the detection of the video signal subjected to the telecine conversion and the progressive conversion process for the normal camera signal are performed. Degradation of image quality due to frequent switching is suppressed.

  Further, the image display device according to the present invention includes a telecine conversion signal detection means for detecting whether or not the input video signal is a telecine-converted video signal, and the input according to the detection result of the telecine conversion signal detection means. And an IP conversion unit that progressively converts the video signal. In an image display device that displays a video signal that has been progressively converted by the IP conversion unit, a noise level detection unit that detects a noise level of the input video signal; and Control means for turning off the detection processing of the telecine conversion signal detection means when the noise level is a predetermined level or more based on the detection result of the noise level detection means.

  Each of the image display devices is equipped with the video signal processing device according to the present invention described above, and displays the video signal subjected to telecine conversion after being subjected to progressive conversion processing. When the noise level of the input video signal is high In addition, deterioration in image quality due to frequent switching between progressive conversion processing for telecine-converted video signals and progressive conversion processing for normal camera signals due to malfunctions in detection of telecine-converted video signals is suppressed. Or, the degradation of image quality due to frequent switching of frame rate conversion processing on and off due to malfunction of detection of video signal converted by telecine is suppressed, and screen failure due to malfunction of motion vector detection Is prevented.

  According to the present invention, a progressive conversion process is performed according to a detection result of whether or not an input video signal is a telecine converted video signal, and a progressive conversion process is performed on a telecine converted video signal. When the post-frame rate conversion process is performed, if the noise level of the input video signal is high, the frame rate conversion process is frequently switched on and off due to malfunction of detection of the video signal subjected to telecine conversion. It is possible to obtain an effect of suppressing the deterioration of the image quality and preventing the screen from being broken due to the malfunction of the motion vector detection.

It is a block diagram which shows the structure of the television receiver to which this invention is applied. It is a figure which illustrates the detection result of a noise level. It is a figure which shows the mode which can be selected with a remote controller. It is a figure which shows the mode switching process by a microcomputer. It is a figure which shows the process for detecting a film signal. It is a figure which shows the process for detecting a film signal. It is a figure which shows the frame rate conversion process by motion compensation.

  Hereinafter, an example in which the present invention is applied to a television receiver will be specifically described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a main part of a television receiver to which the present invention is applied. An interlaced video signal (NTSC) that has been selected and demodulated by the front end 1 and subjected to Y / C separation processing and chroma decoding processing by the chroma decoder 2 based on an RF signal sent to the front end 1 from a receiving antenna (not shown). Signal (480i), PAL signal (576i) or HDTV signal (1080i)) is sent to the noise level detection circuit 3, the IP conversion circuit 4, and the film signal detection circuit 5, respectively.

  The film signal detection circuit 5 is a circuit that detects whether or not the input video signal is a 2: 2 film signal or a 2: 3 film signal by the detection method shown in FIGS. From the film signal detection circuit 5, a signal indicating a detection result (a signal indicating whether the input video signal is a 2: 2 film signal, a 3: 2 film signal, or a normal camera signal) is an IP conversion circuit 4. And sent to the frame rate conversion circuit 6.

  The IP conversion circuit 4 is a circuit that performs an IP conversion process for progressively converting an interlaced input video signal. If the detection result of the film signal detection circuit 5 is a 2: 2 film signal or a 3: 2 film signal, the film signal IP conversion processing (for example, pull-down reverse processing as shown in FIG. 7B for a 2: 2 film signal) is performed. On the other hand, if the detection result of the film signal detection circuit 5 is a normal camera signal, IP conversion processing for camera signals is performed. The video signal (NTSC signal (480p), PAL signal (576p) or HDTV signal (1080p)) progressively converted by the IP conversion circuit 4 is sent to the frame rate conversion circuit 6.

  When the detection result of the film signal detection circuit 5 is a 2: 2 film signal or a 3: 2 film signal, the frame rate conversion circuit 6 applies 25 Hz to the video signal progressively converted by the IP conversion circuit 4 by motion compensation. This is a circuit that performs a frame rate conversion process from 50 Hz to 50 Hz (for example, the process shown in FIG. 7C for a 2: 2 film signal). If the detection result of the film signal detection circuit 5 is a normal camera signal, the frame rate conversion circuit 6 does not perform frame rate conversion.

  The video signal output from the frame rate conversion circuit 6 is sent to the display drive circuit 8, and the display (for example, LCD) 9 is driven by the display drive circuit 8 to display an image.

  The noise level detection circuit 3 is a circuit that detects the noise level of the input video signal. The noise level detection circuit 3 detects, for example, noise information (AC component) of the pedestal part of one horizontal line in the equivalent pulse section in the vertical blanking section of the input video signal, and cuts off the AC component in the field unit as a cutoff frequency. A voltage having a filter of about 160 Hz is detected as a noise value YNLV. Then, noise levels SNLV0 to SNLV7 (steps where SNLV0 has the lowest noise level and SNLV7 has the highest noise level) are detected which are switched in eight steps according to the noise value YNLV.

  FIG. 2 is a diagram illustrating the detection results of the noise levels SNLV0 to SNLV7. FIG. 2A shows that the noise value YNLV increases as the electric field strength Level_dBu of the RF signal from the receiving antenna becomes weaker. FIG. 2B shows the detection result when the noise value YNLV decreases as the electric field strength Level_dBu of the RF signal increases.

  As shown in FIG. 2A, when the electric field strength Level_dBu becomes weaker, the noise level SNLV is switched to 1 when the noise value YNLV is 10 or more (the electric field strength Level_dBu is 70 dBu or less) (the noise level SNLV until then). Is 0), the noise level SNLV is switched to 2 when the noise value YNLV is 20 or more (the electric field strength Level_dBu is 65 dBu or less), and the noise level SNLV is set when the noise value YNLV is 30 or more (the electric field strength Level_dBu is 62 dBu or less). When the noise value YNLV is 50 or more (the electric field strength Level_dBu is 58 dBu or less), the noise level SNLV is switched to 4, and when the noise value YNLV is 70 or more (the electric field strength Level_dBu is 55 dBu or less). The noise level SNLV is switched to 5, the noise level SNLV is switched to 6 when the noise value YNLV is 100 or more (the electric field strength Level_dBu is 50 dBu or less), and the noise level SNLV is switched to the noise value YNLV of 150 or more (the electric field strength Level_dBu is 35 dBu or less). To 7.

  On the other hand, when the electric field strength Level_dBu increases, as shown in FIG. 2B, the noise level SNLV is changed from 7 to 6 even if the noise value YNLV is 150 or less (the electric field strength Level_dBu is 35 dBu or more). Without switching, the noise level SNLV is switched from 7 to 6 only when the noise value YNLV becomes 120 or less (electric field strength Level_dBu is 44 dBu or more) smaller than 150. Further, even if the noise value YNLV becomes 100 or less (the electric field strength Level_dBu is 50 dBu or more), the noise level SNLV is not switched from 6 to 5, and the noise value YNLV is 84 or less (the electric field strength Level_dBu is 53 dBu or more) smaller than 100. The noise level SNLV is switched from 6 to 5 for the first time. Similarly, the noise value YNLV for switching the noise level SNLV to 4, 3, 2, 1, 0 is also set lower than when the electric field strength Level_dBu becomes weaker.

  Thus, the noise level detected by the noise level detection circuit 3 is higher than the electric field strength of the RF signal from the receiving antenna than when the electric field strength of the RF signal becomes weaker (the noise value increases). Has a hysteresis characteristic that when it becomes stronger (the noise value decreases), it is more difficult to recover to a better stage.

  As shown in FIG. 1, the noise level detection circuit 3 sends the detection result of this noise level to the microcomputer 7. In FIG. 1, the noise level detection circuit 3 is provided separately from the chroma decoder 2, but the noise level detection circuit 3 may be provided in the chroma decoder 2.

  Although not shown, the remote controller of the television receiver is provided with an operation unit for the user to select a combination of film signal detection processing, IP conversion processing, and frame rate conversion processing modes. FIG. 3 is a diagram illustrating a combination example of modes that can be selected by the remote controller. In the remote controller, four modes, Mode 1 to Mode 4, can be selected.

  Mode 1 is a mode in which the film signal detection process is turned off. In this mode 1, the film signal detection circuit 5 sends a detection result indicating that the input video signal is a camera signal to the IP conversion circuit 4 and the frame rate conversion circuit 6. Accordingly, the IP conversion circuit 4 always performs the normal camera signal IP conversion process without performing the film signal IP conversion process (pull-down reverse process), and the frame rate conversion circuit 6 performs the frame rate conversion process. Absent.

  In mode 2, the parameter for controlling the detection sensitivity of the film signal detection circuit 5 is set to “film detection 2”, the IP conversion processing (pull-down reverse processing) for the film signal of the IP conversion circuit 4 is turned on, and frame rate conversion is performed. In this mode, the frame rate conversion processing of the circuit 6 is turned off. In mode 2, if a film signal is detected by the film signal detection circuit 5, the IP conversion circuit 4 performs IP conversion processing for the film signal, but the frame rate conversion circuit 6 does not perform frame rate conversion processing.

  Here, parameters for controlling the detection sensitivity of the film signal detection circuit 5 will be described. Film signal (especially 2: 2 film signal) can be detected stably in a scene with a lot of motion because the feature of the field difference shown in FIG. 5 is remarkably detected. In such cases, it is difficult to detect the feature of the field difference. Therefore, it is difficult to detect the film without malfunction in every scene. Therefore, there exists a parameter for controlling the detection sensitivity of the film signal. Here, which of the following two types of parameters “film detection 1” and “film detection 2” is set in the film signal detection circuit 5 is switched according to the mode of FIG.

“Film detection 1”: a parameter that makes it easy to detect a film signal and makes it difficult to detect a film signal once it has been detected (increases detection sensitivity). Specific examples of such parameters include the following.
As shown in FIG. 5 and FIG. 6, the threshold level for determining whether the difference is 0 or 1 when taking the difference for each field is 0, 1, 0, 1,. A parameter that changes alternately or is set to a level that tends to become zero every five fields as shown in FIG.
・ When the 2: 2 film signal repeats 0 and 1 several times, it is determined to be a 2: 2 film signal, and when the 3: 2 film signal becomes 0 every 5 fields, 3: 2 A parameter that decreases the count value for determining film signals.

  “Film detection 2”: Contrary to “Film detection 1”, it is a parameter that makes it difficult to detect a film signal and makes it easy to detect that it is not a film signal even after the film signal has been detected (decreases detection sensitivity). .

  Therefore, in FIG. 3, in mode 2, since the parameter is set to “film detection 2”, the detection sensitivity of the film signal detection circuit 5 is weakened. Therefore, the IP conversion circuit 4 performs IP conversion processing for film signals. It becomes difficult.

  In mode 3, the parameter for controlling the detection sensitivity of the film signal detection circuit 5 is set to “film detection 2”, the IP conversion processing (pull-down reverse processing) for the film signal of the IP conversion circuit 4 is turned on, and frame rate conversion is performed. In this mode, the frame rate conversion processing of the circuit 6 is also turned on. In this mode 3, when the film signal is detected by the film signal detection circuit 5, the IP conversion circuit 4 performs the IP conversion process for the film signal and the frame rate conversion circuit 6 performs the frame rate conversion process. However, since the detection sensitivity of the film signal detection circuit 5 is weakened, it is difficult for the IP conversion circuit 4 to perform IP conversion processing for film signals, and the frame rate conversion circuit 6 is also difficult to perform frame rate conversion processing.

  In mode 4, the parameter for controlling the detection sensitivity of the film signal detection circuit 5 is set to “film detection 1”, the IP conversion processing (pull-down reverse processing) for the film signal of the IP conversion circuit 4 is turned on, and frame rate conversion is performed. In this mode, the frame rate conversion processing of the circuit 6 is also turned on. In this mode 4, when a film signal is detected by the film signal detection circuit 5, an IP conversion process for the film signal is performed by the IP conversion circuit 4 and a frame rate conversion process is performed by the frame rate conversion circuit 6. Since the detection sensitivity of the film signal detection circuit 5 is increased, the IP conversion circuit 4 can easily perform the IP conversion process for the film signal, and the frame rate conversion circuit 6 can easily perform the frame rate conversion process.

  As shown in FIG. 1, the microcomputer 7 is supplied with a signal indicating the selection result of the modes 1 to 4 from the remote controller via an infrared light receiving unit (not shown).

  The microcomputer 7 dynamically switches the mode as shown in FIG. 4 based on the selection result of the mode 1 to mode 4 by the user and the detection result of the noise levels SNLV0 to SNLV7 by the noise level detection circuit 3. The IP conversion circuit 4, the film signal detection circuit 5, and the frame rate conversion circuit 6 are controlled. That is, when the noise level is SNLV0 or SNLV1 (the stage where the RF signal field strength is strong and the noise level is low), the control of the IP conversion circuit 4 and the film are performed according to the mode 1 to mode 4 selected by the user. Control of detection sensitivity of the signal detection circuit 5 (switching of parameters and turning off of detection processing) and on / off control of frame rate conversion processing of the frame rate conversion circuit 6 are performed. In the figure, the control signal line to the IP conversion circuit 4 is not shown (even in the mode 1, even if the pull-down reverse processing of the IP conversion circuit 4 is turned on as in the modes 2 to 4, the film signal is not transmitted. Since it is not detected, IP conversion processing for film signals is not performed).

  When the noise level is SNLV2, SNLV3, SNLV4, or SNLV5 (in the stage where the electric field strength of the RF signal is medium and the noise level is medium), if the user selects mode 1 or mode 2, According to the mode, control of the IP conversion circuit 4, control of the detection sensitivity of the film signal detection circuit 5, and on / off control of the frame rate conversion processing of the frame rate conversion circuit 6 are performed, but the user selects mode 3 or mode 4 In this case, in mode 2, the control of the IP conversion circuit 4, the control of the detection sensitivity of the film signal detection circuit 5, and the on / off control of the frame rate conversion processing of the frame rate conversion circuit 6 are performed. Therefore, in this case, the frame rate conversion circuit 6 does not perform the frame rate conversion process, and the film signal detection sensitivity becomes weak, so that the IP conversion circuit 4 is also difficult to perform the film signal IP conversion process. .

  When the noise level is SNLV6 or SNLV7 (when the electric field strength of the RF signal is weak and the noise level is high), even if the user selects any mode from mode 1 to mode 4, the mode 1 is forcibly set to IP in mode 1. Control of the conversion circuit 4, control of the detection sensitivity of the film signal detection circuit 5, and on / off control of the frame rate conversion processing of the frame rate conversion circuit 6 are performed. Therefore, in this case, the IP conversion circuit 4 always performs the normal camera signal IP conversion process without performing the film signal IP conversion process, and the frame rate conversion circuit 6 also performs the frame rate conversion process. Absent.

By performing such dynamic mode switching, the following effects (1) to (3) can be obtained.
(1) Since the frame rate conversion circuit 6 does not perform the frame rate conversion process by motion compensation at the stage where the electric field strength of the RF signal is weak or intermediate, the frame rate conversion process is performed due to the malfunction of the film signal detection Image quality degradation due to frequent switching between on and off is suppressed, and screen failure due to motion vector detection malfunction is prevented.

  (2) Since the film signal is difficult to detect at the stage where the electric field strength of the RF signal is medium, the IP conversion circuit 4 is difficult to perform the IP conversion processing for the film signal. This suppresses deterioration in image quality due to frequent switching between film signal IP conversion processing and normal camera signal IP conversion processing due to film signal detection malfunction.

  (3) Since the film signal detection process is not performed at the stage where the electric field strength of the RF signal is weak, the IP conversion circuit 4 does not perform the IP conversion process for the film signal and always performs the IP conversion process for the normal camera signal. Is done. This suppresses deterioration in image quality due to frequent switching between film signal IP conversion processing and normal camera signal IP conversion processing due to film signal detection malfunction.

  As shown in FIG. 2, the noise levels SNLV <b> 0 to SNLV <b> 7 have a stronger RF signal field strength than when the RF signal field strength becomes weaker (the noise value increases). It has a hysteresis characteristic that it is harder to recover to a better stage when the noise value is decreasing. Therefore, the field strength of the RF signal increases thereafter, as compared with the case where the control of the microcomputer 7 shifts from the left mode to the right mode in FIG. Therefore, the mode switching is less likely to occur when the control of the microcomputer 7 returns from the right mode to the left mode in FIG. As a result, once the electric field strength of the RF signal is weakened, a mode (mode 1 or mode 2) for suppressing deterioration in image quality is maintained until the electric field strength is sufficiently increased.

  In the above example, the example in which the film signal (the video signal having the movie film as the source) is detected and the progressive conversion process or the frame rate conversion process is performed has been described. However, the video signal targeted for detection processing, progressive conversion processing, and frame rate conversion processing according to the present invention is a television video by arranging original images such as movies, animations, and computer graphics based on a predetermined sequence. Any video signal may be used as long as it is converted (telecine conversion) so as to match the frame rate of the signal.

  In the above example, the present invention is applied to a television receiver. However, the image display apparatus according to the present invention may be applied to, for example, a personal computer having a television broadcast receiving function in addition to the television receiving apparatus. Further, the video processing apparatus according to the present invention may be mounted on, for example, a recording / reproducing apparatus (DVD recorder, HDD recorder, etc.) for receiving and recording / reproducing a television broadcast.

  DESCRIPTION OF SYMBOLS 1 ... Front end, 2 ... Chroma decoder, 3 ... Noise level detection circuit, 4 ... IP conversion circuit, 5 ... Film signal detection circuit, 6 ... Frame rate conversion circuit, 7 ... Microcomputer, 8 ... Display drive circuit, 9 ... Display

Claims (4)

Telecine conversion signal detection means for detecting whether or not the input video signal is a telecine converted video signal;
IP conversion means for progressively converting the input video signal according to the detection result of the telecine conversion signal detection means;
Noise level detection means for detecting a noise level of the input video signal;
Based on the detection result of the noise level detection means, if the noise level is a predetermined level or higher, the control means for turning off the detection process of the telecine conversion signal detection means,
A video signal processing apparatus comprising: The video signal processing device according to claim 1,
The noise level detection means detects a noise level that switches between a plurality of stages according to a noise value, and the noise value is higher than a noise value that switches the noise level stage when the noise value increases. The video signal processing apparatus is characterized in that a noise value for switching the stage of the noise level is set to be lower when the noise level decreases. Telecine conversion signal detection means for detecting whether or not the input video signal is a telecine converted video signal;
IP conversion means for progressively converting the input video signal according to the detection result of the telecine conversion signal detection means,
In an image display device that displays a video signal that has been progressively converted by the IP conversion means,
Noise level detection means for detecting a noise level of the input video signal;
Control means for turning off detection processing of the telecine conversion signal detection means when the noise level is a predetermined level or more based on the detection result of the noise level detection means, apparatus. The image display device according to claim 3,
The noise level detection means detects a noise level that switches between a plurality of stages according to a noise value, and the noise value is higher than a noise value that switches the noise level stage when the noise value increases. An image display device characterized in that the noise value for switching the level of the noise level is set to be lower when the noise decreases.