A general architecture that implements the various features of the invention will now be described with reference to the drawings. The drawings and the associated descriptions are provided to illustrate embodiments of the invention and not to limit the scope of the invention.
Various embodiments according to the invention will be described hereinafter with reference to the accompanying drawings. In general, according to one embodiment of the invention, a pull-down signal detecting apparatus judges whether an input video signal is a pull-down signal or not based on a first unit moving area number obtained in a small area unit for a first high correlation field having a high inter-field correlation between a current field signal and a one-field delay signal, or a second unit moving area number obtained in a small area unit for a second high correlation field having a high inter-frame correlation between the current field signal and a two-field delay signal.
In
Returning to the explanation of
A pull-down signal detecting circuit 14 uses the current field signal S1, the one-field delay signal S2, and the two-field delay signal S3 to judge whether an input video signal is a pull-down signal or not, and outputs a pull-down signal detection signal K1 and a pair-field selection signal K2. The pull-down signal detection signal K1 indicates whether an input video signal is a pull-down signal or not. Further, the pair-field selection signal K2 indicates which of the current field signal S1 and the two-field delay signal S3 is the field to be paired with the one-field delay signal S2. This pull-down signal detecting circuit 14 will be described in detail later.
A first selector 15 selects one of the current field signal S1 and the two-field delay signal S3 as the field to be paired with the one-field delay signal S2 according to the pair field selection signal K2, and outputs the selected signal as a pair field signal S4 to a second selector 16. The second selector 16 selects the pair field signal S4 when the pull-down signal detection signal K1 indicates a pull-down signal or otherwise selects the motion adaptive interpolation signal S5 to output the selected signal as an interpolation signal S6 (second interpolation signal). A scanning line arrangement circuit 17 arranges (combines) the one-field delay signal S2 as a direct signal and the interpolation signal S6 in the order of progressive scanning to output a progressive scan converting signal D1.
The inter-field difference absolute value circuit 23 constitutes together with a small area integration circuit 26 a first difference value calculating device according to the present invention, which calculates an inter-field difference absolute value between respective fields for the current field signal S1 and the one-field delay signal S2. The difference absolute value calculated here is used for obtaining an inter-field correlation between the current field signal S1 and the one-field delay signal S2. An output of the inter-field difference absolute value circuit 23 is inputted to the small area integration circuit 26.
The inter-frame difference absolute value circuit 25 constitutes together with a small area integration circuit 27 a second difference value calculating device according to the present invention, which calculates an inter-frame difference absolute value between respective fields for the current field signal S1 and the two-field delay signal S3. The difference absolute value calculated here is used for obtaining an inter-frame correlation between the current field signal S1 and the two-field delay signal S3. An output of the inter-frame difference absolute value circuit 25 is inputted to the small area integration circuit 27.
The small area integration circuit 26 integrates an inter-field difference absolute value outputted from the inter-field difference absolute value circuit 23 in a small area (area constituted of plural small pixels obtained by segmenting a field) unit (or a pixel unit), and output an inter-field difference value in a small area unit. The small area integration circuit 27 integrates an inter-frame difference absolute value outputted from the inter-frame difference absolute value circuit 25 in a small area unit, and outputs an inter-frame difference value in a small area unit. The output of the small area integration circuit 26 is inputted to an inter-field comparator 28, and the output of the small area integration circuit 27 is inputted to an inter-frame comparator 29. Incidentally, for the small area integration circuits 26, 27, a small area is set to a rectangular area with 8 horizontal pixels×8 vertical lines for example.
The inter-field comparator 28 is a first comparing device according to the present invention and compares the output of the small area integration circuit 26 with a threshold value E1 (a first difference value comparison threshold value). This threshold value E1 is set to a predetermined value capable of detecting an area that can be judged to be moving or to have larger motion (hereinafter referred to as “moving area”) in a small area unit. The inter-field comparator 28 outputs a signal (moving area signal) indicating detection of a moving area when the inter-field difference value outputted from the small area integration circuit 26 is equal to or above the threshold value E1.
The inter-frame comparator 29 is a second comparing device according to the present invention and compares the output of the small-area integration circuit 27 with a threshold value E2 (a second difference value comparison threshold value). This threshold value E2 is also set to a predetermined value capable of detecting a moving area in a small area unit. The inter-frame comparator 29 outputs a signal (moving area signal) indicating detection of a moving area when the inter-frame difference value outputted from the small area integration circuit 27 is equal to or above the threshold value E2.
The moving area signals outputted from the inter-field comparator 28 and the inter-frame comparator 29 are inputted to in-screen counters 30, 31 respectively.
The in-screen counter 30 is a first counting device and counts the number of moving area signals outputted from the inter-field comparator 28 and inputs a moving area count value indicating a result of counting to a small area inter-field comparator 32 and an inter-field accumulated value comparator 34. The in-screen counter 31 is a second counting device and counts the number of moving area signals outputted from the inter-frame comparator 29 and inputs a moving area count value indicating a result of counting to a small area inter-frame comparator 33 and an inter-frame accumulated value comparator 35.
The small area inter-field comparator 32 is a first field detecting device and compares the moving area count value outputted from the in-screen counter 30 in a small area unit with a threshold value E3 to detect a low correlation field (first low correlation field) having a low inter-field correlation. This threshold value E3 is set to a predetermined value capable of detecting a first low correlation field by comparison in a small area unit. The small area inter-field comparator 32 outputs a signal (first low correlation field signal) indicating detection of a first low correlation field when the moving area count value reaches or surpasses the threshold value E3, in other words, the number of moving areas (the number of moving areas is also referred to as “moving area number”) detected by the inter-field comparator 28 reaches or surpasses the threshold value E3.
The small area inter-frame comparator 33 is a second field detecting device and compares the moving area count value outputted from the in-screen counter 31 in a small area unit with the threshold value E4 to detect a low correlation field (second low correlation field) having a low inter-frame correlation. This threshold value E4 is set to a predetermined value capable of detecting a second low correlation field by comparison in a small area unit. The small area inter-frame comparator 33 outputs a signal (second low correlation field signal) indicating detection of a second low correlation field when the moving area count value reaches or surpasses the threshold value E4, in other words, the number of moving areas detected by the inter-frame comparator 29 reaches or surpasses the threshold value E4.
The inter-field accumulated value comparator 34 compares the moving area count value outputted from the in-screen counter 30 with a threshold value E5 in a field unit and outputs a signal indicating the comparison result thereof to an inter-field pattern detecting circuit 36. This threshold value E5 is set to a predetermined value capable of detecting a low correlation field having a low inter-field correlation in a field unit. Further, the inter-frame accumulated value comparator 35 compares the moving area count value outputted from the in-screen counter 31 with a threshold value E6 and outputs a signal indicating the comparison result thereof to an inter-frame pattern detecting circuit 37. This threshold value E6 is set to a predetermined value capable of detecting a low correlation field having a low inter-frame correlation in a frame unit.
The inter-field pattern detecting circuit 36 is a first pattern detecting device and detects based on a signal inputted from the inter-field accumulated value comparator 34 whether or not an inter-field correlation between plural fields such as sequential five fields for example matches a particular pattern of a pull-down signal such as 2-3 pull-down signal, 2-2 pull-down signal or the like, and outputs a signal indicating a detection result thereof. The inter-frame pattern detecting circuit 37 is a second pattern detecting device and detects based on a signal inputted from the inter-frame accumulated value comparator 35 whether or not an inter-frame correlation between plural fields such as sequential five fields matches a particular pattern of a pull-down signal, and outputs a signal indicating a detection result thereof.
A screen unit pull-down signal judgment circuit 38 is a field unit pull-down signal detecting device and performs the following judgment based on the signal outputted from the inter-field pattern detecting circuit 36 and the signal outputted from the inter-frame pattern detecting circuit 37. Specifically, the screen unit pull-down signal judgment circuit 38 judges whether an input video signal is a pull-down signal or not in a predetermined number of fields and outputs a screen unit pull-down signal detecting signal G3 which indicates a judgment result thereof. Further, the screen unit pull-down signal judgment circuit 38 outputs an inter-field correlation flag G1 indicating high or low of an inter-field correlation judged in a screen unit and an inter-frame correlation flag G2 indicating high or low of an inter-frame correlation judged in a screen unit. The screen unit pull-down signal detecting signal G3 indicates a detection result of a pull-down signal performed in a screen unit. Further, the screen unit pull-down signal judgment circuit 38 outputs the pair field selection signal K2 when the input video signal is a pull-down signal.
An inter-field pull-down signal judgment circuit 39 performs the following judgment based on the first low correlation field signal outputted from the small area inter-field comparator 32, the inter-field correlation flag G1 and the screen unit pull-down signal detecting signal G3.
The inter-field pull-down signal judgment circuit 39 judges whether or not the first low correlation field signal is outputted from the small area inter-field comparator 32 when an inter-field correlation is high in a screen unit and thus it is judged to be a high correlation field (the high correlation field judged at this time corresponds to a first high correlation field according to the present invention) in a state that the pull-down signal in a screen unit is detected. The inter-field pull-down signal judgment circuit 39 judges that the input video signal is not a pull-down signal when the first low correlation field signal is outputted, and outputs a pull-down signal detection signal H1 showing a judgment result thereof.
Further, since the first low correlation field signal is outputted when a moving area number between fields reaches or surpasses the threshold value E3, it turns out that the inter-field pull-down signal judgment circuit 39 carries out the above judgment based on the moving area number (first unit moving area number) between fields obtained in a small area unit for the first high correlation field.
An inter-frame pull-down signal judgment circuit 40 performs the following judgment based on the second low correlation field signal outputted from the small area inter-frame comparator 33, the inter-frame correlation flag G2 and the screen unit pull-down signal detecting signal G3.
The inter-frame pull-down signal judgment circuit 40 judges whether or not the second low correlation field signal is outputted from the small area inter-frame comparator 33 when an inter-frame correlation is high in a screen unit and thus it is judged to be a high correlation field (the high correlation field judged at this time corresponds to a second high correlation field according to the present invention) in a state that the pull-down signal in a screen unit is detected. The inter-frame pull-down signal judgment circuit 40 judges that the input video signal is not a pull-down signal when the second low correlation field signal is outputted, and outputs a pull-down signal detection signal H2 showing a judgment result thereof.
Further, since the second low correlation field signal is outputted when a moving area number between frames reaches or surpasses the threshold value E4, it turns out that the inter-frame pull-down signal judgment circuit 40 carries out the above judgment based on the moving area number (second unit moving area number) between frames obtained in a small area unit for the second high correlation field.
A pull-down signal judgment circuit 41 outputs the pull-down signal detection signal K1 based on the pull-down signal detection signals H1, H2 and the pull-down signal detecting signal G3. The pull-down signal detection signal K1 indicates that an input video signal is not a pull-down signal (or is a non-pull-down signal) when the first unit moving area number for the first high correlation field reaches or surpasses the threshold value E3, or the second unit moving area number for the second high correlation field reaches or surpasses the threshold value E4 in a state that the pull-down signal in a screen unit is detected. These inter-field pull-down signal judgment circuit 39, inter-frame pull-down signal judgment circuit 40 and pull-down signal judgment circuit 41 constitute a pull-down signal judging device according to the present invention.
Then, the pull-down signal detecting circuit 14 having the above configuration has the following characteristics. This point will be described with respect to
In general, when an input video signal is a pull-down signal (
There are an inter-field correlation between the current field signal S1 and the one-field delay signal S2 and an inter-frame correlation between the current field signal S1 and the two-field delay signal (one-frame delay signal) S3.
Here, the case is assumed that the current field signal S1 is continuously a pull-down signal after a fourth field BE at time T4. Then, with a case of low correlation being called dynamic (Dc) and a case of high correlation being called static (Sc) for both inter-field and inter-frame, inter-field correlations and inter-frame correlations from a second field BE at time t2 to a sixth field Bo at time t6 should be as follows respectively. Specifically, the inter-field correlations should be Dc-Sc-Sc-Dc-Sc, and the inter-frame correlations should be Dc-Dc-Sc-Dc-Dc.
However, as shown in
Accordingly, in the progressive scan converting circuit 1, timing of performing a motion adaptive interpolation deviates. Then, selection of the motion adaptive interpolation signal S5 by the second selector 16 to output the interpolation signal S6 occurs in a seventh field at time t7 or thereafter. Also, at time t6, the pair field selection signal K2 is outputted, and the interpolation signal S6 for which the pair field signal S4 is selected is outputted, so that wrong pull-down processing (combining processing of corresponding fields) is performed for the field C in the sixth field and the sixth field D (in this embodiment, the wrong pull-down processing is also referred to as erroneous interpolation). When this erroneous interpolation is performed, noise in a comb shape is generated.
However, in the progressive scan converting circuit 1 according to the present invention, since the pull-down signal is detected by the pull-down signal detecting circuit 14 configured as above, it is possible to reduce generation of the noise in a comb shape as will be described later even when switching from a 2-3 pull-down scene to a normal video scene.
Hereinafter, referring to flowcharts shown in
As shown in
When proceeding to block 2, the pull-down signal detecting circuit 14 judges whether it is sequential or not for the period of a predetermined number of fields. Here, the pull-down signal detecting circuit 14 proceeds to block 3 when it is sequential, or it proceeds to block 5 when it is not sequential.
When proceeding to block 3, the pull-down signal detecting circuit 14 judges whether an inter-frame correlation is detected to be “Dc” or not in a field where it should be “Sc”. The pull-down signal detecting circuit 14 proceeds to block 5 when it is detected to be “Dc”, or it proceeds to block 4 when it is not detected to be “Dc”.
Then, the pull-down signal detecting circuit 14 judges that it is a pull-down signal in block 4, or judges that it is a non-pull-down signal in block 5, and thereafter completes the detection of a pull-down signal in a screen unit.
Meanwhile, the pull-down signal detecting circuit 14 executes block 12 and thereafter of the detection procedure of a pull-down signal shown in
When starting the detection procedure of a pull-down signal shown in
The pull-down signal detecting circuit 14 proceeds to block 13 when it is a field where an inter-field correlation is “Sc” in block 12, or otherwise terminates the process. The pull-down signal detecting circuit 14 judges whether the moving area number between fields is equal to or above the threshold value E3 in block 13.
Further, the pull-down signal detecting circuit 14 proceeds to block 15 when it is judged in step 13 that the moving area number between fields is equal to or above the threshold value E3 to judge it as a non-pull-down signal and terminates the process, or otherwise proceeds to block 14. When proceeding to block 14, the pull-down signal detecting circuit 14 judges whether it is the end of a screen or not, and returns the process to block 13 to repeat it when it is not the end of a screen, or otherwise terminates the process.
The pull-down signal detecting circuit 14 performs the same process for an inter-frame correlation. Specifically, the pull-down signal detecting circuit 14 judges in block 16 whether or not it is a field where an inter-frame correlation is “Sc” (the above-described second high correlation field) on the pull-down sequence. Here, when it is a field of “Sc”, the pull-down signal detecting circuit 14 proceeds to block 17 to judge whether the moving area number between frames is equal to or above the threshold value E4, or otherwise terminates the process.
Further, the pull-down signal detecting circuit 14 proceeds to block 19 when it is judged in block 17 that the moving area number between frames is equal to or above the threshold value E4 to judge it as a non-pull-down signal and terminates the process, or otherwise proceeds to block 18. When proceeding to block 18, the pull-down signal detecting circuit 14 judges whether it is the end of a screen or not, and returns the process to block 17 to repeat it when it is not the end of a screen, or otherwise terminates the process.
Further, when the pull-down signal detecting circuit 14 executed blocks 15, 19, the pull-down signal detection signal K1 indicates that it is a non-pull-down signal.
As above, the pull-down signal detecting circuit 14 is capable of judging as a non-pull-down signal with either the first high correlation field or the second high correlation field when the moving area number between fields reaches or surpass the threshold value E3 or the moving area number between frames reaches or surpasses the threshold value E4. Accordingly, the pull-down signal detecting circuit 14 is capable of judging as a non-pull-down signal even when it is in middle of a screen. Then, the second selector 16 selects the motion adaptive interpolation signal S5. Therefore, the progressive scan converting circuit 1 having this pull-down signal detecting circuit 14 is capable of stopping the progressive scanning conversion by means of the pull-down processing (corresponding field combination) even in middle of a screen to switch to the progressive scanning conversion by means of the motion adaptive interpolation. Therefore, it is possible to reduce generation of noise in a comb shape when switching from a 2-3 pull-down scene to a normal video scene as shown in
The above operation being a characteristic of the present invention in the pull-down signal detecting circuit 14 is described in accordance with the flowcharts shown in
The above explanation is for the embodiment of the present invention and is not to limit the apparatus and method according to the present invention, and various modification examples can be simply implemented. Further, any device or method configured by appropriately combining components, functions, characteristics or method steps in each embodiment is included in the present invention.
As described in detail above, according to the present invention, the pull-down signal detecting apparatus and the pull-down signal detecting method and the progressive scan converting apparatus and the progressive scan converting method which are capable of reducing generation of noise in a comb shape when switching from a pull-down signal to a normal video signal can be obtained.
While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.
Number | Date | Country | Kind |
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P2006-098392 | Mar 2006 | JP | national |