CN1096185C - Interlaced-to-progressive conversion apparatus and method using motion and spatial correlation - Google Patents

Abstract

The interlaced to progressive conversion device includes a spatial interpolator, which spatially interpolates the input interlaced image signal and outputs a spatially interpolated signal; a time interpolator, which temporally interpolates the input interlaced image signal and outputs a time interpolated signal; a correlator , to detect the motion correlation, the vertical correlation, and the time vertical correlation by using a predetermined number of sampled data in the current field, the previous field, and the next field; and a selector for comparing the motion correlation, the vertical correlation, and the time vertical correlation A predetermined constant is compared, and one is selected between the spatially interpolated signal and the temporally interpolated signal according to the comparison result. It can enhance the reliability of motion information and reduce artifacts by temporally or spatially interpolating interlaced image signals using motion and spatial correlation.

Description

The interlacing of using motion and space correlation is to conversion equipment and method line by line

The present invention relates to use the interlacing of motion and space correlation to changing (interlaced-to-progressive conversion) apparatus and method line by line.Particularly, the present invention relates to by space or time ground interpolation interlaced image signal be converted to the apparatus and method of progressive video signal according to motion and space correlation.

Usually, interlacing has been widely used in many artifacts (artifacts) that minimizing causes because of interlacing scan to changing (IPC) device line by line, that is, glimmering such as the vertical resolution deterioration in the systems such as NTSC, PAL, SECAM, scan line flicker and wide territory.

Recently, because high definition TV (HDTV) system adopted for the multiple standards of signal format and often need change between the standard input/output signal of different-format, therefore, interlacing has become more important to conversion equipment line by line.

In early days the stage development interlacing of getting up to transfer algorithm line by line for using such as systems such as NTSC, PAL, SECAM.The various algorithms that proposed are excluded the interpolation of the row beyond interlacing scan usually based on playback.

The list of references [1] that " is used for reducing the comparison of the interpolater of the medium filtering of flicker and vertical edge control " by D.I.C.Hentschei being entitled as of delivering at No. 3 279-289 page or leaf of IEEE journal consumer electronics (consumer electronics) the 35th volume in August, 1989 disclose these artifacts of minimizing that proposed algorithm, repeat with the interpolating method of vertical filtering with based on the method for vertical edge information according to simple row.

Go up the interpolating method that discloses in the list of references of delivering by D.Bagni, R.Lancini, S.Landi and S.Tubaro [2] that is entitled as " the HD-TV space-time is to up conversion " according to edge direction at 1994 " HDTV international symposium proceedings ".

Non-linear high speed interpolation method based on weighted median filter is disclosed in the list of references [3] that " uses the scan rate conversion of weighted median filtering " in being entitled as of delivering by J.Juhola, A.Nieminen, J.Salo and Y.Neuvo of IEEE ISCAS-89 proceedings 433-436 page or leaf of in May, 1989 U.S. Portland.

Algorithm based on FIR intermediate value compound filter is disclosed in the list of references [4] that is entitled as " non-linear quincunx interpolation filtering " delivered by A.Lehtonen and M.Renfors of " SPIE face-to-face communication and image processing proceedings " 132-135 page or leaf of Switzerland Lausanne in October nineteen ninety.

Go up the algorithm that discloses in the list of references of delivering by H.Blume, L.Schwoerer and K.Zygis [5] that is entitled as " based on the subband that uses complementary median filter " based on complementary median filter to up conversion at 1994 " HDTV international symposium proceedings ".

Be located at the L.Chiariglione Ed. of North Holland, Elsevier Science Press discloses in the list of references [6] that is entitled as " interlacing that EDTV uses is to conversion line by line " of T.Doyle that " HDTV signal processing " 421-430 page or leaf in 1988 is delivered based on the algorithm according to the medium filtering of direction.

The list of references of delivering by P.Frenchen at No. 3 237-240 page or leaf of IEEE journal consumer electronics in 1986 the 32nd volume [7] that is entitled as " two integrated progressive conversion devices "; Algorithm based on vertical-time median filter is disclosed with the list of references [8] that is entitled as " television image medium filtering " that " IEEE technical papers digest " 186-187 page or leaf of 1986 is delivered by T.Doyle and P.Frencken.

In addition, the list of references of delivering by people such as N.Suzuki at No. 3 266-271 page or leaf of IEEE journal consumer electronics the 33rd volume in August, 1989 [9] that is entitled as " the improvement resultant motion signal that in the IDTV receiver, is used for improving the Motion Adaptive pre-scan converted "; By the list of references [10] that is entitled as " having the Motion Adaptive pre-scan converted device that two-dimensional silhouette strengthens " that C.P.Markhauser delivers the Motion Adaptive scheme is disclosed with No. 2 110-114 page or leaf of IEEE journal consumer electronics the 36th volume in May nineteen ninety.

Above interlacing can roughly be divided into the three-dimensional interpolating method of spatial interpolation method, temporal interpolation method and spatial interpolation and temporal interpolation combination to conversion method line by line.

In three-dimensional interpolating method because wrong temporal interpolation can cause the deterioration in image quality such as artifact is torn (tearing-artifact), the motion in the detected image and according to the motion that is detected suitably the time of implementation interpolation be very important.This is owing to owing to time sampling speed in the actual image signal causes the limited fact of maximum time frequency that can determine in theory less than Nyquist (Nyquist) speed.

Yet, just as proposed by the present invention: the reliability that can increase movable information by the spatial information that uses sampling with movable information.

An object of the present invention is a kind of interlacing to conversion equipment line by line, be used for converting interlaced image signal to progressive video signal by carrying out spatial interpolation or temporal interpolation according to motion and space correlation.

Another object of the present invention is a kind of three-dimensional interlacing to conversion method line by line, is used for according to motion and space correlation selection and one of output region interpolation or temporally interpolated picture signal.

For achieving the above object, provide a kind of be used for will input the interlaced image signal interlacing that converts progressive video signal to conversion equipment line by line, comprising: the spatial interpolation device is used for interlaced image signal and output region interpolated signal that spatial interpolation is imported; The temporal interpolation device is used for interlaced image signal and output time interpolated signal that temporal interpolation is imported; Relevant apparatus is used for interlaced image signal and relevant, vertical relevant be correlated with vertical with the time of output movement imported by using the sampled data of working as front court, previous field and next predetermined quantity to import; And choice device, be used for relevant, the vertical relevant vertical relevant and corresponding predetermined constant with the time of motion is compared, and between spatial interpolation signal and temporal interpolation signal, select one according to comparative result.

For realizing above-mentioned another purpose, provide a kind of be used for will input the interlaced image signal interlacing that converts progressive video signal to conversion method line by line, comprise step: (a) interlaced image signal and the output region interpolated signal imported of spatial interpolation; (b) interlaced image signal and the output time interpolated signal imported of temporal interpolation; (c) it is relevant, vertical relevant vertical with the time relevant to detect motion from the interlaced image signal of being imported; (d) if the motion correlation that is detected greater than first predetermined constant, by selecting the spatial interpolation signal; (e) if the motion correlation is not more than first predetermined constant and the vertical correlation that detected greater than second predetermined constant, select time interpolated signal then; (f) if the motion correlation is not more than that first predetermined constant and vertical correlation are not more than second predetermined constant and the vertical correlation of time that detected greater than the 3rd predetermined constant, then select the spatial interpolation signal; If (g) the motion correlation is not more than that first predetermined constant is not more than second predetermined constant with vertical correlation and vertical correlation of time is not more than the 3rd predetermined constant, by the select time interpolated signal.

Can make above-mentioned purpose of the present invention and advantage become more obvious by being described in detail with reference to the attached drawings its preferred embodiment.Wherein:

Fig. 1 be according to the present invention interlacing to the block diagram of an embodiment of conversion equipment line by line;

Fig. 2 is the more detailed block diagram of space correlator shown in Figure 1;

Fig. 3 explanation is used to switch the geometrical relationship of the sampling of space or temporal interpolation signal; With

Fig. 4 describes space correlator in the selector shown in Figure 1 is used to switch the method for space or temporal interpolation signal according to output signal flow chart.

Below, the interlacing of using motion and space correlation is described with reference to the drawings to conversion equipment and method and preferred embodiment thereof line by line.

Fig. 1 be according to the present invention interlacing to the block diagram of an embodiment of conversion equipment line by line.

This interlacing comprises a spatial interpolator 110, temporal interpolation device 120, correlator 130, a selector 140 to conversion equipment line by line.

The interlaced image signal Vin that spatial interpolator 110 uses pre-defined algorithm to come spatial interpolation to import.

Temporal interpolation device 120 uses pre-defined algorithm to come the interlaced image signal Vin of this input of temporal interpolation.

Correlator 130 detects relevant (hereinafter being referred to as " vertical being correlated with of time ") DT between the relevant DM of motion, relevant (hereinafter being referred to as " vertical direction the is relevant ") DV of vertical direction and temporal interpolation and the vertical interpolation from the interlaced image signal imported.

Selector 140 will move relevant DM, vertically the vertical relevant DT of relevant DV with the time respectively with predetermined constant TM, T1 and T2 relatively, and according to comparative result select by the signal Is of spatial interpolator 110 outputs or by the signal It of temporal interpolation device 120 outputs so that it is exported as interpolated signal Vout.

The operation of this device shown in Figure 1 is described now.

Among Fig. 1, interlaced image signal Vin is applied to spatial interpolator 110, temporal interpolation device 120 and correlator 130.

Simultaneously, owing to the present invention relates to switch the progressive video signal (hereinafter being referred to as " spatial interpolation signal ") and the temporally interpolated progressive video signal (hereinafter being referred to as " temporal interpolation signal ") of spatial interpolation and export selected signal, therefore have nothing to do with in spatial interpolator 110 and temporal interpolation device 120, using any spatial interpolation algorithm and temporal interpolation algorithm respectively according to movable information and spatial information.

Correlator 130 is imported interpolated signal Vin and is detected the relevant DM of motion, the vertical DT of being correlated with the time of the relevant DV of vertical direction from interlaced image signal Vin.After this, correlator 130 output signal DM, DV and DT.

Selector 140 will move relevant DM, vertically the vertical relevant DT of relevant DV with the time respectively with predetermined constant TM, T1 and T2 comparison, and select, and export selected signal Vout by the signal Is of spatial interpolator 110 outputs or the signal It that exports by temporal interpolation device 120.

Fig. 2 is the more detailed block diagram of correlator shown in Figure 1.

Sampling delayer 201,203,204 and 206, row delayer 202 and 205 constitute the first sampling detector, and detect sampling w1 to w5.Field memory 210, sampling delayer 211 and 213, row delayer 212 constitute the second sampling detector, and detect sampling x1 and x2.In addition, field memory 220, sampling delayer 221,223,224 and 226, row delayer 222 and 225 constitute the 3rd sampling detector, and detect sampling v1 to v5.

Motion correlator 230 receives sampling v1 and v5 and w1 and w5, and the relevant DM with output movement of calculating.Subtracter 241 and absolute value circuit 242 receive sampling v1 to v3 and w1 to w5, and calculate vertical relevant DV with output.In addition, adder 251 and 252, subtracter 253 and absolute value circuit 254 receive sampling x1, x2, v3 and w3, and the vertical relevant DT with output time of calculating.

Geometrical relationship shown in Fig. 3 key diagram 2 between the sampling.

Among Fig. 3, sampling " x " expression will be by the sampling of interpolation (being called as " current interpolation sampling ") recovery.The sampling that has the par position in sampling " x1 " the expression previous row with current interpolation sampling.In addition, the sampling that has the par position in sampling " x2 " the expression next line with current interpolation sampling.

The sampling that has same position with current interpolation sampling in sampling " v3 " the expression previous field.Sampling " v2 " and " v4 " is the previous and back sampling of sampling v3.In addition, and sampling " v1,, represent to have with sampling v3 in the previous row sampling of par position.The sampling that has the par position in sampling " v5 " the expression next line with sampling v3.

Equally, the sampling that has same position with current interpolation sampling is represented in next in sampling " w3 ".Sampling " w2 " and " w4 " is the previous and back sampling of sampling w3.In addition, the sampling that has the par position in sampling " w1 " the expression previous row with sampling w3.The sampling that has the par position in sampling " w5 " the expression next line with sampling w3.

Equally, be odd field if work as the front court, because this input signal is the interlace signal of input, previous field and next then are even fields.In addition, be even field if work as the front court, previous field and next then are odd fields.

With reference now to Fig. 3, the operation of device shown in Figure 2 is described.

In Fig. 2, interlaced image signal Vin is imported into field memory 210, sampling delayer 201 and row delayer 202.

Also export the picture signal that is delayed a field duration for one of the picture signal Vin that field memory 210 storages are imported.Field memory 220 is from the picture signal of these delays of field memory 210 input, store of picture signal of this delay, and output compared the picture signal that is delayed two field duration with the original input signal Vin that is imported. Field memory 210 and 220 is made of first-in first-out (FIFO) memory.

Sampling delayer 201 input interlaced image signal Vin with 1 sampling period of this signal delay, and export sampling w5 shown in Figure 3 next.The delayer 202 of going receives this input signal Vin, with 1 horizontal line cycle of this signal delay, and exports sampling w4 when sampling delayer 201 output sampling w5.Sampling delayer 203 will be gone 1 sampling period of signal delay of delayer 202 outputs, and export sampled signal w3.Sampling delayer 204 will be taken a sample 1 sampling period of signal delay of delayer 203 outputs, and export sampled signal w2.Row delayer 205 will be gone 1 horizontal line cycle of signal delay that delayer 202 is exported.Sampling delayer 206 will be gone 1 sampling period of signal delay of delayer 205 outputs, and export sampled signal w1.

Simultaneously, sampling delayer 211 further will be from 1 sampling period of the signal delay that is delayed 1 field duration of field memory 210, and output sampling x2.Row delayer 212 is with 1 horizontal line cycle of signal delay of field memory 210 outputs.Sampling delayer 213 will be gone 1 sampling period of signal delay of delayer 212 outputs, and export sampled signal x1.

Sampling delayer 221 further will be from 1 sampling period of the signal delay that is delayed 2 field duration of field memory 210, and output sampling v5.Row delayer 222 is with 1 horizontal line cycle of signal delay of field memory 220 outputs, and output sampling v4.Sampling delayer 223 will be gone 1 sampling period of signal delay of delayer 222 outputs, and export sampled signal v3.Sampling delayer 224 will be taken a sample 1 sampling period of signal delay of delayer 223 outputs, and export sampled signal v2.Row delayer 225 will be gone 1 horizontal line cycle of signal delay that delayer 222 is exported.Sampling delayer 226 will be gone 1 sampling period of signal delay of delayer 225 outputs, and export sampled signal v1.

Motion correlator 230 receives the sampling v1 to v5 of previous field and the sampling w1 to w5 of next, calculates and the relevant DM of output movement.At this moment, calculate the relevant DM of motion of motion correlator 230 outputs by formula (1). $\mathrm{DM}=\underset{i=1}{\overset{5}{\mathrm{\Σ}}}\mathrm{ai}|\mathrm{vi}-\mathrm{wi}|...\left(1\right)$ Wherein, ai is predefined coefficient.

The relevant DM of motion is used for estimating whether the adjacent of the position of the sampling that will be recovered by interpolation produces the measurement result (x of Fig. 3 is the geometry mid points of x1 and x2) of motion.

Subtracter 241 deducts the sampled data x2 by 211 outputs of sampling delayer from the sampled data x1 by 213 outputs of sampling delayer, and the result is subtracted each other in output.After this, absolute value circuit 242 calculates and subtracts each other result's absolute value and export this absolute value as vertical relevant DV.

Therefore, the vertical relevant DV of available formula (2) expression.

DV＝|x1-x2| …(2)

Adder 251 is added to sampled data w3 with sampled data v3.Adder 252 is added to sampled data x2 with sampled data x1.

Subtracter 253 deducts the signal by adder 252 outputs from the signal by adder 251 outputs, and the result is subtracted each other in output.After this, absolute value circuit 254 calculates and subtracts each other result's absolute value and export this absolute value as vertically relevant DT of time.

Therefore, the vertically relevant DT of available formula (3) express time.

DT＝|(v3+w3)-(x1+x2)| …(3)

The relevant DM of motion of motion correlator 230 outputs, the vertical relevant DT with the time of absolute value circuit 254 outputs of vertical relevant DV of absolute value circuit 242 outputs are input to selector shown in Figure 1 140.

The operation of selector 140 is described with reference to flow process shown in Figure 4.

Among Fig. 4, selector 140 will move relevant DM and constant TM comparison (step S101).If the relevant DM of motion produces constant of the motion TM greater than showing, selector 140 selections and output are from the spatial interpolation signal (step S102) of spatial interpolator 110.

If the relevant DM of motion is not more than constant of motion TM in step S101, selector 140 will vertically be correlated with DV and constant T1 comparison (step S103).If vertically relevant DV is greater than constant T1, selector 140 selections and output are from the temporal interpolation signal It (step S104) of temporal interpolation device 120.

At this, the DV that when the relevant DM of motion is not more than constant TM, will vertically be correlated with reason that constant T1 compares be because can by the artifact of the temporal interpolation generation of mistake by the size of the vertical DV of being correlated with visually impression different.As vertical relevant DV during,, visually be not easy to perceive the artifact that the temporal interpolation because of mistake produces because picture signal is relevant littler in vertical direction greater than constant T1.Therefore, when DM is not more than TM and DV greater than T1, by selector 140 select and output from the signal It (step S104) of temporal interpolation device 120.

Yet, when DM less than TM and DV during less than T1, the artifact that the easier temporal interpolation of visually awaring because of mistake produces.Therefore, selector 140 according to show that vertically relevant DT of time relevant between temporal interpolation and the vertical interpolation selects and output from the signal Is of spatial interpolator 110 or from the signal It of temporal interpolation device 120.

That is, when the relevant DM of motion was not more than constant TM and vertically relevant DV and is not more than constant T1, selector 140 compared (step S105) with vertically relevant DT of time with constant T2.If vertically relevant DT of time is greater than constant T2, because relevant less between temporal interpolation and the vertical interpolation, signal Is from spatial interpolator 110 is selected and exported to selector 140, so that reduce the influence (step S106) of artifact.Simultaneously, if vertically relevant DT of time is not more than constant T2, because being correlated with between temporal interpolation and the vertical interpolation is bigger, selector 140 selections and output are from the output signal It (step S107) of temporal interpolation device 120.

As mentioned above, interlacing according to the present invention is used motion and space correlation interpolation interlaced image signal to conversion equipment and method line by line with coming time or space, and strengthens the reliability of relevant movable information and reduce artifact effectively.

Claims (14)

1. An interlaced to progressive conversion device for converting an input interlaced image signal into a progressive image signal, comprising: A spatial interpolation device, used for spatially interpolating the input interlaced image signal and outputting a spatially interpolated signal; A time interpolation device, used for time interpolating the input interlaced image signal and outputting a time interpolation signal; correlation means for inputting the input interlaced image signal and outputting motion correlation, vertical correlation, and time vertical correlation by using a predetermined number of sampled data in the current field, the previous field, and the next field; and selecting means for comparing the motion correlation, the vertical correlation, and the time vertical correlation with corresponding predetermined constants, and selecting one between the spatially interpolated signal and the temporally interpolated signal according to the comparison result. 2. The interlaced to progressive conversion device according to claim 1, wherein the motion space correlation device comprises: The first detection means is used to detect the motion correlation between the first sample group and the second sample group, the first sample group includes the first sample at the same position as the current interpolation sample, the sample before the first sample In the field before the samples after the first sample and the samples at the same horizontal position as the first sample in the previous line and the next line, the second sample group includes the first sample at the same position as the current interpolation sample. In the second sample, the sample before the second sample and the sample after the second sample and in the next field of the samples at the same horizontal position as the second sample in the previous line and the next line; second detecting means for detecting the vertical correlation by calculating the difference between the samples in the previous line and the next line of the current field at the same horizontal position as the current interpolated sample; and Third detection means for detecting the temporal vertical correlation by calculating the difference between the sum of the first sample and the second sample and the sum of samples in the previous line and the next line of the current field at the same horizontal position. 3. The interlaced to progressive converting device according to claim 2, wherein the second detecting device comprises: A first subtractor for subtracting samples at the same horizontal position in the next line of the current field from samples at the same horizontal position in the previous line of the current field and outputting a first subtraction result; and The first absolute value circuit is used to determine the absolute value of the first subtraction result. 4. The interlaced to progressive conversion device according to claim 2, wherein the third detecting device comprises: a first adder for adding the first sample to the second sample; The second adder is used to add the samples at the same horizontal position in the previous row and the next row of the current field; a second subtractor for subtracting the output of the second adder from the output of the first adder and outputting a second subtraction result; and The second absolute value circuit is used to determine the absolute value of the second subtraction result and output the time vertical correlation. 5. The interlaced to progressive conversion device according to claim 2, further comprising: The first sampling detection device is used to detect the first sampling group; A second sample detection means for detecting samples in the previous line and the next line of the current field at the same horizontal position as the current interpolation sample; and The third sampling detection device is used for detecting the second sampling group. 6. The interlaced to progressive conversion device according to claim 5, wherein the first sampling detection device comprises: The first sampling delayer is used to input an interlaced image signal and delay the signal by one sampling period; The first line delayer is used to input an interlaced image signal and delay the signal by one horizontal line period; a second sampling delay for inputting the output of said first line delay and delaying the signal by one sampling period; a third sampling delay for inputting the output of said second sampling delay and delaying the signal by one sampling period; a second row delayer for inputting the output of said first row delayer and delaying the signal by one horizontal row period; and The fourth sampling delayer is used for inputting the output of the second line delayer and delaying the signal by one sampling period. 7. The interlaced to progressive conversion device according to claim 5, wherein the second sampling detection device comprises: The first field memory is used to input an interlaced image signal and delay the signal by one field period; a fifth sampling delayer for inputting the output of said first field memory and delaying the signal by one sampling period; a third row delayer for inputting the output of said first field memory and delaying the signal by one horizontal row period; and The sixth sampling delayer is used for inputting the output of the third line delayer and delaying the signal by one sampling period. 8. The interlaced to progressive conversion device according to claim 5, wherein the third sampling detection device comprises: a second field memory for inputting the output of said first field memory and delaying the signal by one field period; a seventh sampling delayer for inputting the output of said second field memory and delaying the signal by one sampling period; a fourth row delayer for inputting the output of said second field memory and delaying the signal by one horizontal row period; an eighth sampling delay for inputting the output of said fourth line delay and delaying the signal by one sampling period; a ninth sampling delay for inputting the output of said eighth sampling delay and delaying the signal by one sampling period; a fifth row delayer for inputting the output of said fourth row delayer and delaying the signal by one horizontal row period; and The tenth sampling delayer is used for inputting the output of the fifth line delayer and delaying the signal by one sampling period. 9. The interlaced-to-progressive converting apparatus according to claim 1, wherein said selecting means selects and outputs the spatially interpolated signal if the motion correlation value is greater than a first predetermined constant. 10. The interlaced to progressive conversion device according to claim 1, wherein if the motion correlation value is not greater than the first predetermined constant and the vertical correlation value is greater than a second predetermined constant, the selection means selects and outputs the time interpolation Signal. 11. The interlaced to progressive conversion device according to claim 1, wherein if the motion correlation value is not greater than the first predetermined constant and the vertical correlation value is not greater than the second predetermined constant, and the detected time vertical correlation value is greater than one A third predetermined constant, said selection means then selects and outputs a spatially interpolated signal. 12. The interlaced to progressive conversion device according to claim 1, wherein if the motion correlation value is not greater than the first predetermined constant and the vertical correlation value is not greater than the second predetermined constant and the time vertical correlation value is not greater than the third predetermined constant, the selection means selects and outputs the time-interpolated signal. 13. An interlaced to progressive conversion method for converting an input interlaced image signal into a progressive image signal, comprising the following steps: (a) spatially interpolating the input interlaced image signal and outputting a spatially interpolated signal; (b) time-interpolating the input interlaced image signal and outputting the time-interpolation signal; (c) detecting motion correlation, vertical correlation, and temporal vertical correlation from the input interlaced image signal; (d) selecting a spatially interpolated signal if the detected motion correlation value is greater than a first predetermined constant; (e) if the motion correlation value is not greater than the first predetermined constant and the detected vertical correlation value is greater than a second predetermined constant, then select the temporally interpolated signal; (f) selecting a temporally interpolated signal if the motion correlation value is not greater than the first predetermined constant and the vertical correlation value is not greater than the second predetermined constant and the detected temporal vertical correlation value is greater than a third predetermined constant; and (g) Selecting a temporally interpolated signal if the motion correlation value is not greater than the first predetermined constant and the vertical correlation value is not greater than the second predetermined constant and the time vertical correlation value is not greater than the third predetermined constant. 14. The interlaced to progressive conversion method according to claim 13, wherein said step (c) comprises the steps of: (c1) detecting a motion correlation between a first sample group comprising a first sample at the same position as the current interpolated sample, a sample preceding the first sample, and a second sample group at In the samples after the first sample and in the field before the samples at the same horizontal position as the first sample in the previous line and the next line, the second sample group includes the second sample, the sample before the second sample and the sample after the second sample and in the next field of the samples at the same horizontal position as the second sample in the previous line and the next line; (c2) detecting the vertical correlation by calculating the difference between the samples in the previous line and the next line of the current field at the same horizontal position as the current interpolated sample; (c3) The temporal vertical correlation is detected by calculating the difference between the sum of the first sample and the second sample and the sum of the samples in the previous line and the next line of the current field at the same horizontal position.

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