JP6099132B2 - Field order detection apparatus, method and program - Google Patents

Description

  The present invention relates to a field order detection apparatus that automatically detects the temporal order of fields in an interlaced video by visual analysis and without reference to header information of a video file.

  Many of the current television signal systems are designed on the assumption that interlace (interlace) scanning is performed in the monitor device. The interlace signal is composed of two fields, and it is assumed that the odd line number (the number of the first appearing line in the signal format is 1 (not 0), and is numbered 2, 3, 4 ...) A set of odd numbers 1, 3, 5,... Is called a top field, and a set of even numbers (2, 4, 6,...) Is called a bottom field. The display time of the top field and the bottom field is shifted by a half of one frame period, and the effective image area is scanned in one of the field orders determined for each signal format.

  In general, a field order in which the top field is scanned (displayed) first in time and then the bottom field is scanned is referred to as top first, and vice versa. Note that, in any field order, the first line of the effective image area is defined as a field scanned in time.

  However, the FPD (Flat Panel Display), which occupies most of the monitor devices manufactured in recent years, employs a display method based on progressive scanning, and displays interlaced video signals. Uses a process called field merging to simultaneously display the top field and bottom field lines as a single frame. This field merging can be said to be processing performed to bring the appearance of a video on a monitor that does not support interlace display such as FPD closer to that of a monitor that supports interlace display. In the video equipment and the PC, various video processes are applied to the video signal in the field merge state.

  At this time, it is necessary to store the field order before processing, that is, to match the top / bottom field types of the first line of the effective image area before and after processing. This is because the video signal input to the video equipment or PC has a flag indicating the field order (F flag in the standard SMPTE259M / 292M, ([STMPTE]; Society of Motion Picture and Television Engineers)) This is because the field type can be identified, but since such information is usually lost inside the device, there is no other way but to take over the preconditions before processing.

  However, depending on the combination of video equipment, there are cases where the field order setting cannot be properly taken over. In addition, depending on the device, it is necessary for the user to manually specify the field order, and if the setting is incorrect due to lack of understanding of the specification of the user or error, the field order may be reversed unintentionally as a result. there is a possibility. In such a case, the time relationship between the fields is reversed, so that it is perceived as an abnormality such that the moving image is not reproduced smoothly. Further, when the subsequent video processing includes processing depending on the field order, there is a possibility that an unintended processing result is generated.

  As a countermeasure against such field order inversion, a method of determining the presence or absence of an abnormality by visually confirming the processed image is conceivable. However, as described above, in recent years, FPD devices that do not support interlaced display are the mainstream in video monitors, and it is difficult to prepare an environment for visual observation.

  In response to such a situation, Patent Documents 1 and 2 provide a method and apparatus for automatically determining a field order from an analysis of a video signal.

  Japanese Patent Laid-Open No. 2004-228561 includes a means for determining a field order as preprocessing for compression encoding, and realizes a function of changing the field order at the timing when the video is stopped. However, the field order change is limited to the conversion from bottom-first to top-first, and it can be said that the problem is low versatility.

  With respect to the above-mentioned problem, Patent Document 2 discloses a highly versatile method intended to change the field order in both directions. From the temporal variation of the motion vector obtained by applying motion prediction to the video to be determined, Means are provided for detecting an abnormality in motion due to order reversal.

Japanese Patent Laid-Open No. 2005-5904 “Image Compression Device” JP 2007-81500 A "Image processing apparatus, method and program for determining field order of moving image data"

  However, Patent Document 2 that intends to change the field order in both directions to enhance versatility has the following problem. That is, in Patent Document 2, information on motion vectors detected in units of pixel blocks is used to detect motion abnormalities. However, since implementation of motion vector detection requires a very large calculation cost, There is concern about an increase in processing time.

  The present invention provides a field order detection apparatus that has a function of automatically determining the field order of an input image in view of the above-described problems of the prior art, and that can be implemented simply with low calculation cost. With the goal.

  In order to achieve the above object, the present invention provides a field order detection apparatus for detecting a field order of an input video using only a pixel signal of the input video, and an even field signal for each frame of the input video. And a field separator for separating into odd field signals, a field memory for storing the even field signals and odd field signals in association with frame numbers, and the even field signals for each frame number. Sorting by even field generating earlier signal by placing odd field signal later and odd field producing earlier signal by placing odd field signal first and placing even field signal later And the even field are the previous signal and the odd field. Compare the difference intensity calculation unit for calculating the interframe difference intensity for each of the previous signals and the calculated interframe difference intensity, and the even field has a smaller interframe difference intensity of the previous signal. A field order determination unit that determines that the input video is preceded by an even field, and determines that the odd video is preceded by an odd field if the odd field has a small inter-frame difference strength of the previous signal. It is characterized by providing.

  According to the present invention, it is possible to create an even field signal and an odd field signal assuming each field order from the input video, and to automatically determine the field order of the input video by comparing the difference intensities thereof. Therefore, it is not necessary to perform visual confirmation using an interlace-compatible monitor, and it is possible to reduce the load on work and equipment. At this time, since the determination is made by comparing the difference intensities, the determination can be made with a lower calculation load than in the case of calculating a motion vector or the like.

It is a functional block diagram of the field order detection apparatus which concerns on one Embodiment. It is a figure which shows typically that an input image | video is isolate | separated and accumulate | stored in the signal of each field by a field separation part and a field memory. It is a figure for demonstrating typically two kinds of signals obtained by a sort part. It is a functional block diagram of the field order detection apparatus which concerns on another one Embodiment.

  FIG. 1 is a functional block diagram of a field order detection apparatus according to an embodiment. The field order detection apparatus 10 includes a field separation unit 1, a field memory 2, a sorting unit 3, a difference intensity calculation unit 4, and a field order determination unit 5, and receives an uncompressed video signal as an input, and determines the field order of the input video Output the result.

The input video signal is an uncompressed video signal, and is input to the field order detection device 10 in the order of frame numbers. The frame number is f, the horizontal pixel position is x, the line number is y, and the input signal is I _in (f, x, y). In the following, f, x, and y are counters starting from 0.

  The field separation unit 1 separates the input video signal into two fields. Here, for a line number y, y mod 2 = 0, that is, a set of lines where y is an even number is an even field, and y mod 2 = 1, ie, a set of lines where y is an odd number Are referred to as odd fields. Note that the name of top / bottom is not used because the order is not fixed at this point.

Based on the above names, the field separation unit 1 converts the input signal I _in (f, x, y) into the even field signal I ₀ (f , x, y) and the odd field signal I ₁ (f, x, y), and pass them to the field memory 2.

  The field memory 2 stores the separated field signals for the sorting process in the subsequent sorting unit 3. The field memory 2 outputs a signal value of an arbitrary field when there is a reference request in each subsequent processing unit. The field memory 2 may be realized by an arbitrary medium having a data storage function, such as a memory or a hard disk.

  FIG. 2 is a diagram schematically showing the processing in the field separation unit 1 and the field memory 2 described above. The even field (line number y = 0, 2, 4,...) Is white and the odd field ( Line numbers y = 1, 3, 5, ...) are drawn in gray. The input video as shown in (1) is separated and accumulated into an even field signal as shown in (2) and an odd field signal as shown in (3). As shown in the figure, if the size of each frame of the input video is horizontal X and vertical Y, each separated signal is half the vertical size, and the size is horizontal X and vertical Y / 2. Become.

  As described in FIG. 2 with respect to the size of each of the even-numbered field signal and the odd-numbered field signal, the sorting unit 3 has a vertical size that is half of the input signal, and the scanning order is a series of progressive scanning. It is regarded as a progressive frame of and rearranged in order of time. Here, since it is not possible to determine at this point in time which of the constituent frames of the even / odd field signal is earlier, two sort order signals are generated and passed to the difference intensity calculation unit 4 .

That is, J _E (f, x, y) is the signal with the even field first (EFF; Even Field First) and J _O (f, x, y) is the signal with the odd field first (OFF; Odd Field First). Then, both are defined as (Formula 2-1) and (Formula 2-2), respectively.

Here, EO represents an even field (when I _{EO on} the right side of each equation is an even field signal), and _EO represents an odd field (I _{EO on} the right side of each equation is an odd field signal). An integer with 1 in some cases. Also, inv () is a function that inverts 0 and 1.

  FIG. 3 is a diagram for schematically explaining the two types of signals obtained by the sorting unit 3. In the same manner as in the example of FIG. 2, the even field is drawn in white and the odd field is drawn in gray. The EFF (Even Field First) sort shown on the upper side (A) is the case of (Equation 2-1), and even fields are displayed first for fields belonging to the same frame f of the input video. On the other hand, the OFF (Odd Field First) sort shown in the lower row (B) is the case of (Equation 2-2), and the arrangement is reversed with respect to (A), and the odd field is displayed first.

  As shown in the “time axis” of FIG. 3, the even / odd fields in the f-th frame (described as “frame f” on the upper (A) and (B) sides) in the original input video are each sorted. In accordance with the sort order in the signal, it corresponds to the 2f-th and 2f + 1-th frames in each sort signal.

One of the sort signals J _E (f, x, y) and J _o (f, x, y) defined by (Equation 2-1) and (Equation 2-2) above is in the correct time order. In other words, since the sorting is performed in accordance with the field order in the initial input video, the video looks natural and smooth. On the other hand, since the other is not temporally matched, there is a problem with the appearance of the video. In other words, when considering the sort signals J _E (f, x, y) and J _o (f, x, y) from the viewpoint of the time change of the signal, the signal moving in the correct time order is smoother and changes. Is small, but the other updates the signal while fluctuating around the correct time order.

Therefore, a signal in the correct time order is between video fields (note that even / odd fields appear alternately on the frame time axis as shown in FIG. 3 in the sort signal, so that “inter-field” is between adjacent frames). The difference signal component is expected to be small. Therefore, in the present invention, based on the difference signal in the time direction of the sort signals J _E (f, x, y) and J _o (f, x, y), the smoothness of the motion of the video is determined and The smaller difference is adopted as the correct field order.

Based on the above viewpoint, the difference intensity calculation unit 4 performs inter-field (ie, between adjacent frames) for each sort signal J _E (f, x, y) and J _o (f, x, y). An index of the magnitude of the difference signal is obtained. As the index, differential power according to the following (Equation 3-1), which is often used for signal evaluation in general, may be used.

Here, the sum is calculated for all the pixels (x, y) in the f-th frame (f-th frame), and the total number of pixels is N _F in the denominator.

In addition, for the purpose of avoiding a large number of multiplications and avoiding an increase in calculation load, the difference absolute value sum of (Equation 3-2) below may be used, or generalized as follows (Equation 3 -3) L ^p spatial distance (a distance defined by the absolute value of the p power) may be used.

  That is, (Equation 3-3) is the most general case, and the inter-frame difference intensity is calculated as the sum of the power of the pixel difference absolute value between frames (the sum of the p-th power). When the power index p is 1, (Equation 3-2), and when the power index p is 2, (Expression 3-1).

In the above (Expression 3-1) to (Expression 3-3), various even intensity fields D _E (f) are different from the previous sort signal J _E (f, x, y). Given that, by replacing J _E (f, x, y), etc. in each equation with J _O (f, x, y), etc., the odd field becomes the previous sort signal J _O (f, x , y), the respective indices D _O (f) can be obtained in the same manner. (In other words, the subscript E representing an even number in each expression may be replaced with the subscript O representing an odd number.)

The field order determination unit 5 determines the field order based on the magnitude of the difference intensity between the frames of each sort signal output by the difference intensity calculation unit 4. As a criterion for the judgment, the magnitude relationship between the difference intensities D _E (f) and D _O (f) of each sort signal in each frame f is compared, and the total signal (f = 0, 1, 2, ...) is compared. A method (majority voting method) for outputting the field order in the sort signal having a large number of frames with small difference intensity as the correct field order can be used.

Specifically, the voting function Vote (f) based on the magnitude comparison of the difference intensities D _E (f) and D _O (f) of each sort signal in each frame f is defined as shown in (Equation 4-1) below. . The determination formula of the correct field order is given by the following (Equation 4-2) by obtaining the voting function Vote (f) over the entire series of frames f (fεsequence) of the sort signal.

In other words, the voting function Vote (f) in (Equation 4-1) uses the order of “even field first” when the difference strength D _E (f) of “even field first” (EFF) is smaller. Since it is more likely to be correct, one vote is cast on the “even field first” side for the frame f. In the opposite case, 0 votes are cast on the “even field first” side, and on the contrary, it is asserted that the possibility of “odd field first” (OFF) is high.

  By voting the vote function Vote (f) with (Equation 4-2), if the sum of the "even field first" thrown "1" on the correct side is the majority, the correct field order is " The even field is first. On the other hand, if the majority is not reached, the correct field order is “odd number field first”.

  In this way, the determination result “even / odd field first” can be obtained for the input video composed of even lines / odd lines as described in FIG. Here, when actually determining whether the input video is top-first or bottom-first, the top / bottom attribute of the first line of the effective area differs depending on the signal standard. The standard needs to be known. In the present invention, even when the signal standard is unknown, it is possible to determine the field order from the viewpoint of the time order of at least the even line / odd line.

  In addition, in the vote of (Equation 4-2), if each sort signal has a total number of frames of 2N, the difference intensity is obtained (2N−1), so the “total number of frames” in (Equation 4-2) The number of differential intensities (2N-1). If the result is very close to half of the total number of frames as a result of the predetermined threshold determination, and it is difficult to make an order determination, a message to that effect may be output.

In addition, regarding the voting function Vote (f) in (Equation 4-1), it is especially the case that the difference intensity is counted as 1 vote or 0 vote for a frame with a small difference and a frame with a large difference, especially for a pattern with little movement. There is also a concern that a misjudgment may occur. To avoid this, there is a difference between D _E (f) and D _O (f) that exceeds a given threshold TH (> 0) as shown in (Equation 4-1-1) below. Only the frame f may be included in the vote.

  When applying the above (Equation 4-1-1) to the vote of (Equation 4-2), that is, when the threshold value TH is not exceeded (in the case of "otherwise"), the vote of the frame f is treated as an "invalid vote" And do not count to the “total number of frames” in (Equation 4-2).

  Further, as another embodiment, the voting function as in (Equation 4-1) is not used, and the side of the smaller sum is compared by comparing the magnitudes of the sums of difference intensities as in (Equation 4-3) below. It may be determined that the field order corresponding to is correct. Similar to (Formula 4-2), if the judgment is severe with a small margin, it may be output.

  FIG. 4 is a functional block diagram of a field order detection device 10 according to another embodiment, and further includes an output video format designation unit 6 and a field order inversion unit 7 in addition to the configuration of FIG. It has become.

  In this embodiment, as in the case of the embodiment described with reference to FIG. 1, the field separation unit 1 to the field order determination unit 5 function to obtain the field order determination result, and the determination result and the designation input from the user Based on the above, as an additional function by the added units 6 and 7, when necessary, the field order in the input video is corrected in the correct order, that is, the field order is inverted, and an output video is obtained.

  The output video format designation unit 6 accepts designation of a signal format standard assumed in the input video, and inevitably, a signal format standard to be followed by the output video, by manual input from the user. The output video format designation unit 6 identifies the field order type defined in the signal format standard input by the user and outputs it to the field order inversion unit 7.

  For this reason, the output video format designating unit 6 prepares and holds a correspondence table of various existing signal format standards and corresponding field order types in advance, and refers to the correspondence table so that the user can The field order type corresponding to the specified format is obtained.

  As an example of the contents described in the correspondence table, if it is 1080 / 60i (60 field / second HDTV signal), it is 525/60 (60 field / second SDTV signal) to be the top first in SMPTE292M. If so, since SMPTE 259M defines bottom first, this field order type is output.

  The field order reversing unit 7 compares the user-desired output form presented by the output of the output video format designating unit 6 with the field order determination result in the field order determination unit 5, and if there is a difference, the input signal Invert the field order to output.

  For example, if it is assumed that the input video in FIG. 4 starts from the line at the upper end of the effective area (the information on the premise can also be accepted from the user at the same time as the format designation), if the input video is an HDTV signal, Since the determination result of “even field first” represents “top first”, it is inverted when the determination result of “odd field first” is reached. In the case of an SDTV signal, the determination result of “even field first” represents “bottom first”, and is therefore inverted when the determination result of “odd field first” is reached.

  Note that the input video can be obtained for each field signal from the field memory 2 as shown in FIG. 4, and the field order can be inverted. If there is no difference and there is no need for field order inversion, video output is performed while maintaining the field order of the input signal.

  10 ... Field order detection device, 1 ... Field separation section, 2 ... Field memory, 3 ... Sort section, 4 ... Difference intensity calculation section, 5 ... Field order determination section, 6 ... Output video format designation section, 7 ... Field order inversion Part

Claims (9)

A field order detection device that detects a field order of an input video using only a pixel signal of the input video,
A field separation unit that separates into even field signals and odd field signals for each frame of the input video;
A field memory for storing the even field signal and the odd field signal in association with a frame number;
For each frame number, the even field generates the previous signal by placing the even field signal first and the odd field signal later, and the odd field signal is placed first and the even field signal later. A sorting unit in which the odd field generates the preceding signal by arranging; and
A difference intensity calculator for calculating an inter-frame difference intensity for each of the even field and the odd field; and
The calculated inter-frame difference intensity is compared, and if the even field has a small inter-frame difference intensity of the previous signal, it is determined that the input field is the even field first, and the odd field is the previous signal. A field order detection apparatus comprising: a field order determination unit that determines that an odd field precedes an input field if an interframe difference intensity is small.   The field order detection device according to claim 1, wherein the difference intensity calculation unit calculates an inter-frame difference intensity as a power sum of pixel difference absolute values between frames.   The field order detection apparatus according to claim 2, wherein a power index in the power is 1 or 2. 4.   The field order determination unit performs voting on which signal has a smaller inter-frame difference strength in each frame, and performs the determination based on a result of the voting in all frames. 4. The field order detection device according to any one of items 3 to 3.   The field order determination unit, when performing a vote on which signal has a smaller interframe difference strength in each frame, determines that the difference between the interframe difference strengths does not exceed a predetermined threshold value, The field order detection apparatus according to claim 4.   4. The field order detection apparatus according to claim 1, wherein the field order determination unit performs the determination based on a comparison of a sum total of each signal of interframe difference intensity. An output video format designating unit that accepts designation of information identifying the format of the input video from the user and checks a field order in the identified format by referring to a predetermined correspondence table;
A field order inversion unit that inverts and outputs the field order of the input video when the field order checked is different from the field order determined by the field order determination unit; The field order detection apparatus according to claim 1. A field order detection method for detecting a field order of an input video using only a pixel signal of the input video,
A field separation step for separating each frame of the input video into an even field signal and an odd field signal;
Storing the even field signal and the odd field signal in a field memory in association with a frame number;
Referring to the field memory, for each frame number, the even field generates the first signal by arranging the even field signal first and the odd field signal after, and the odd field signal first. A sorting step in which the odd field generates the previous signal by placing and placing the even field signal later;
A difference intensity calculating step of calculating an inter-frame difference intensity for each of the even field and the odd field; and
The calculated inter-frame difference intensity is compared, and if the even field has a small inter-frame difference intensity of the previous signal, it is determined that the input field is the even field first, and the odd field is the previous signal. A field order detection method comprising: a field order determination step of determining that an odd field precedes an input field if an inter-frame difference strength is small. Computer
A field order detection device that detects a field order of an input video using only a pixel signal of the input video,
A field separation unit that separates into even field signals and odd field signals for each frame of the input video;
A field memory for storing the even field signal and the odd field signal in association with a frame number;
For each frame number, the even field generates the previous signal by placing the even field signal first and the odd field signal later, and the odd field signal is placed first and the even field signal later. A sorting unit in which the odd field generates the preceding signal by arranging; and
A difference intensity calculator for calculating an inter-frame difference intensity for each of the even field and the odd field; and
The calculated inter-frame difference intensity is compared, and if the even field has a small inter-frame difference intensity of the previous signal, it is determined that the input field is the even field first, and the odd field is the previous signal. A program that causes a function of a field order detection device that includes a field order determination unit that determines that an odd field comes first if the difference intensity between frames is small.