Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N7/00—Television systems
  • H04N7/01—Conversion of standards, e.g. involving analogue television standards or digital television standards processed at pixel level
  • H04N7/0112—Conversion of standards, e.g. involving analogue television standards or digital television standards processed at pixel level one of the standards corresponding to a cinematograph film standard
  • H04N7/0115—Conversion of standards, e.g. involving analogue television standards or digital television standards processed at pixel level one of the standards corresponding to a cinematograph film standard with details on the detection of a particular field or frame pattern in the incoming video signal, e.g. 3:2 pull-down pattern
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N7/00—Television systems
  • H04N7/01—Conversion of standards, e.g. involving analogue television standards or digital television standards processed at pixel level
  • H04N7/0117—Conversion of standards, e.g. involving analogue television standards or digital television standards processed at pixel level involving conversion of the spatial resolution of the incoming video signal
  • H04N7/012—Conversion between an interlaced and a progressive signal
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N7/00—Television systems
  • H04N7/01—Conversion of standards, e.g. involving analogue television standards or digital television standards processed at pixel level
  • H04N7/0127—Conversion of standards, e.g. involving analogue television standards or digital television standards processed at pixel level by changing the field or frame frequency of the incoming video signal, e.g. frame rate converter
  • H04N7/0132—Conversion of standards, e.g. involving analogue television standards or digital television standards processed at pixel level by changing the field or frame frequency of the incoming video signal, e.g. frame rate converter the field or frame frequency of the incoming video signal being multiplied by a positive integer, e.g. for flicker reduction

Definitions

• the present invention relates to a method for video processing, wherein possible movement between successive fields of the images split into even and odd is detected and the mode, i.e. video mode or film mode is determined.
• the invention relates to the processing of video signals from a video tape, a DVD, a laser disc, a tuner, etc. and therefore of standard PAL, SECAM and NTSC video signals.
• the movement detection is carried out by detecting possible movement of the edges of the fields, the result being that rapid intervention will take place in the event of many details in a field.
• This requires a large number of auxiliary devices such as a battery of correlators.
• the movement detection i.e. the detection of the abovementioned sequence of movement and standstill
• the movement detection can be performed by a three-point median filtering operation, after which the result of said median filtering operation and the incoming information of a following field is filtered by two low-pass filters, the absolute difference of the result of these two low- pass filters is calculated and the differences are summed, the sum, possibly divided by a number, being compared with a threshold value, the result of said comparison forming the abovementioned sequence, stored in a memory, of the movement and standstill between successive fields.
• the video signals to be processed are preferably subjected to doubling, and preferably also quadrupling and preferably also field rate doubling.
• the invention also relates to an apparatus which is particularly suitable for employing the method according to any one of the above embodiments .
• the invention therefore relates to an apparatus which includes a movement detector, a film mode/video mode detector connected thereto, synchronization means to synchronize processing with the film phase, and a film processor proper.
• the movement detector is connected to a median filter having as inputs the current field and the next field of the video images, and includes two low-pass filters, one of which connects to the output of the median filter and the other has as an input the information of the next incoming field, a differentiator which connects to the two low-pass filters to calculate the difference between the outputs of these, a summator connected to said differentiator, a counter connected to said summator and a comparator connected thereto for comparing the output of the counter with a threshold value.
• the film mode/video mode detector includes a shift register in which the result of the comparator over a number of fields is stored, so that a comparison is possible with a pattern inherent to a specific mode.
• the apparatus may include means for employing doubling and/or means for performing quadrupling, and a field rate converter from 50 or 60 Hz to 100 or 120 Hz.
• Figure 1 represents a block diagram of an apparatus used for implementing the method according to the invention
• Figure 2 schematically represents the 2:2 pull- down conversion and processing
• Figure 3 schematically represents the movement sequence between the fields in the case of film processed by 2:2 pull-down;
• Figure 4 schematically represents the 3:2 pull- down conversion and processing
• Figure 5 schematically represents the movement sequence between the fields in the case of film processed of 3:2 pull-down.
• the interlacing is firstly moved and the video is therefore first converted to non-interlaced video.
• each frame consists of two fields, successive even and odd fields being shifted by half a line with respect to one another.
• the three-point median has as its input the pixels lying vertically above one another of two successive lines from the current field coming in via 1A and the pixel vertically below of the intermediate line of the following field coming in via IB.
• the result of the median processing combined with the original lines of the current image, provides a movement-compensated image of 625 or 525 lines, noninterlaced, and 50/60 Hz.
• the result of the median filter 1 is stored in a memory bank (display bank) 2 which consists of two image FIFOs 3 and 4 which are written in interlaced form. The even pixels go to FIFO 3 , the odd pixels to FIFO 4.
• Doubling is the constant read-out of the display bank 2 at the normal rate .
• a memory bank (display bank) 6 which, like the abovementioned, consists of two image FIFOs 7 and 8 which are written in interleaved form.
• the even pixels go to FIFO 7, the odd pixels to FIFO 8.
• a line of the display bank 2 and a line of the display bank 6 is read alternately by a memory controller 9, the result being relayed to a digital-to-analogue converter 10.
• Each line consists of 1024 pixels, 512 even pixels from FIFO 3 or 7, and 512 odd pixels from FIFO 4 or 8 , which are read out in interleaved form and in the correct pixel phase.
• a total image of 1250 or 1050 lines, non-interlaced is obtained a line frequency of 64 kHz and a frame rate of 50 or 60 Hz, respectively.
• field rate upconversion which involves increasing the frequency to 100 to 120 Hz.
• the lines of the abovementioned display bank 2 are read out by the memory controller 9 twice in succession and at twice the normal rate and therefore at a frequency of 100 or 120 Hz instead of 50 or 60 Hz, an image being formed which has 625 or 525 lines, respectively, non-interlaced, displayed at double the frame rate.
• the line frequency is then 64 kHz.
• the memory controller 9 in a second embodiment, first reads out the entire contents of the display bank 2 at twice the normal rate and then, at twice the normal rate, reads out the entire contents of the display bank 6. Since both display banks 2 and 6 are alternately read out at twice the rate, a resulting field rate of 100 or 120 Hz will again be obtained.
• the outgoing vertical frame pulse (100/120 Hz) is then, every other frame, shifted upwards by half a 64 kHz line.
• the information from the one display bank ends up in between the information of the other display bank 6, which produces optimal screen coverage within the same time as with normal quadrupling (20 ms or 16.6 ms) .
• This type of image because of the interlacing using non-equidistant frame pulses instead of equidistant frame pulses, can be used only on equipment which supports this type of interlacing, such as HDTV- compatible equipment.
• the frame pulse for the second 100 or 120 Hz field must be calculated.
• the length of the frame is measured on the basis of the number of 64 kHz lines in an original field.
• the second frame pulse is positioned in the middle between two original frame pulses . Without interlacing, equidistant 100 or 120 Hz frame pulses will be obtained.
• the field rate upconversion can therefore be applied both to the doubling technique and to the quadrupling technique, with the option of doubling and quadrupling being employed separately, in conjunction with field rate upconversion or without it.
• the display bank 2 is constantly read out at normal rate, in the case of quadrupling every other line of the display banks 2 and 6 are read out at normal rate, in the case of doubling and field rate doubling the display bank 2 is read out constantly at double the rate, whereas in the case of quadrupling and field rate doubling, complete fields are read out alternately from the display banks 2 and 6 at double the rate, followed by interlacing with respect to the frame pulse.
• the apparatus is able to process transmissions in other modes, including film mode or derivatives thereof such as video editing mode transmissions, in which mixing takes place of normal video images with film mode images, and film editing mode, in which the input consists entirely of film mode images, but the correct sequence is missing.
• film mode i.e. normal video recordings in which movement can take place between each field (20 or 16.6 ms interval
• video editing mode transmissions in which mixing takes place of normal video images with film mode images
• film editing mode in which the input consists entirely of film mode images, but the correct sequence is missing.
• Film mode can take the form of so-called “2:2 pulldown” , in which 24 film images per second are converted into PAL 50 Hz with 50 images per second or 30 film images per second are converted into NTSC 60 Hz with 60 images per second, or of so-called “3:2" pull-down", where 24 film images per second are converted into NTSC 60 Hz and therefore 60 images per second.
• the film in order to be transmitted in the PAL transmission standard, is slightly accelerated to 25 images per second, and each film image or frame is then split into an even and an odd image or field, so that two fields A and B or C and D or E and F etc . are obtained which match one another and occupy the same temporal position but are spatially situated on a different location, i.e. are separated, as seen vertically, by half a scan line, as represented in the top section of Figure 2.
• Each field A, B, C etc. consists of lines, 312.5 lines in the case of PAL, which in Figure 2 exist as Ao A]_, A2, etc. for field A, Bo, Bi, etc. for field B, etc.
• the original film image can be restored by the even and odd field successively being shown and interlaced on the monitor.
• each image or frame is analogously split into an even and an odd field.
• frames consisting of an even and an odd field are composed from, on the one hand, even and odd fields from the same instant and, on the other hand, an even field of one instant and an odd field of the other instant, for example from odd field A, even field A', odd field A, even field B, odd field B' , etc, so that ultimately 60 images per second are again achieved.
• a median filter 1 In the above-described de-interlacing, use is made of a median filter 1 to obtain correct movement compensation.
• a median filter has the drawback, however, that it cannot readily cope with lines moving diagonally with the result that small steps or serrations, so-called "j aggies", are produced on the diagonals.
• the de-interlacing must be effected without a median filter.
• prefiltering is performed as a first step.
• Successive fields A (comprising lines Ao , Ai , etc) and B (comprising lines Bo, Bi, etc), which may match, do come from the same instant but, as a result of the image having been split vertically when film was converted to video transmission, they differ spatially.
• the movement correlation is performed on the low frequencies and not on sharp transitions or details, in order not to be too strongly dependent on the net bandwidth of the input signal and on the possible errors of the median filter 1. Then, for each pixel, the absolute difference is calculated, in the differentiator 15, between the result of the low-pass filter 13 for the result of the median filter, and the low-pass filter 14 for the incoming next image .
• This process is carried out over an entire field, but preferably also limited or keyed by so-called “windowing” from a specific start line to a specific stop line and from a specific start pixel to a specific stop pixel .
• the output of the counter 17 yields a number which, in principle, indicates that degree of movement between two successive video fields.
• a relevant criterion is defined for determining whether there is indeed movement or standstill .
• the calculation of the threshold value for the movement criterion takes account of the luminance value of the current image being processed.
• the threshold value used for movement is an empirically determined fraction of the sum of the luminance values, for example l/64th. Depending on the current processing operation, this threshold value can be doubled or halved.
• an edge boost is employed prior to movement detection taking place, which may be required for architectural reasons in the case of quadrupling, details of fine structures may after all play a significant part in determining the threshold value so that it is necessary, in calculating this threshold value, to take account of the status of the edge boosting device.
• This additional adjustment of the threshold value as a compensation for the edge boost is carried out simultaneously on the nominal value, for example l/64th of the luminance value, double the value and half the value .
• the threshold value is then tailored to the processing mode. If this processing mode is the detection mode with continuous monitoring of the incoming data, the movement detection is set to nominal sensitivity, for example l/64th of the luminance value.
• the movement detection is set to low sensitivity, for example twice the nominal threshold value.
• film resynchronization mode In the case of a third mode, the film resynchronization mode (referred to as “film resync mode”), where the system is still in film mode but the movement detection in a single instance has detected an incorrect film phase, the processing reverts to standard median processing and the movement detection is set to high sensitivity, for example half the nominal threshold value, to enable rapid detection.
• the abovementioned threshold value for movement is determined at the end of each field.
• the film mode/video detection proper then takes place as follows:
• the shift register 19 has a length of a number of bits, for example eleven bits, which means that the history of the movement detector 11 can be measured over a number of fields, for example eleven fields.
• a detector 20 scans the sequence of the shift register 19 for a specific pattern inherent to the various modes.
• the output of the detector 20 is connected, via 20A to the comparator 18 for feedback of the threshold value which, in fact, is determined in said detector 20.
• the detector 20 When the detector 20 observes a movement frequency 1111111, it is assumed that ordinary video obtains, which must be processed via standard median filtering.
• the system upon detecting a 2:2 or 3:2 "pull-down mode" sets the film mode indication high, which means that the movement detector 11 must be set to insensitive mode and that the processing synchronization must be started.
• the detection length of the movement detection is also switched over to a shorter word length of, for example, six bits instead of eleven bits.
• the median filter 1 is switched off and matching fields are merged, and the merged image is repeated, as will be explained below in more detail.
• the apparatus includes a synchronizer 21 comprising two oscillating shift registers, one of which, hereinafter referred to as "3:2 pull-down syncer" 22, produces the sequence 10100 and repeats it indefinitely, or in other words continuously produces the 3:2 pull-down processing sequence, while the other one, hereinafter referred to as “2:2 pull-down syncer” 23 produces the sequence 01 and repeats it or, in other words, continuously produces the 2:2 pull-down processing sequence.
• 3:2 pull-down syncer two oscillating shift registers
• the output of the synchronizer 21 connects, via 21A, to the abovementioned memory controller 9.
• the relevant pull-down syncer 22 or 23 is synchronized by a synchronization pulse coming from the film mode/video detection, for example from the detector 20. From that instant, the processing operation is subjected to the activated syncer 22 or 23 which indeed runs entirely synchronously with the incoming film phase.
• the activated syncer 22 or 23 also serves as a monitor reference for the film mode/video detection.
• the syncer 22 or 23 outputs a zero, and the detector 20 outputs one, an error has crept into the film phase (malfunction in the video source, too many vertical on/off structures, situation of video editing, incorrectly fitted "cue flashes” etc) .
• the apparatus will go into film resync mode, the movement detector 11 being set to very high sensitivity, and the processing will temporarily be switched back to median filtering.
• the output of the synchronizer 21 forms part of a feedback loop, via 21B, to the detector 20.
• the apparatus will then switch over to normal video mode, i.e. normal median filtering, and will again start to search for film mode using an eleven-bit word length for the history of the movement detector 11 and a nominal sensitivity. From this position, given sufficient movement, the correct film phase will be found again relatively rapidly.
• the switch-over in the sensitivity of the movement detector 11 can be disabled via an interface. There is then a choice of three fixed settings of the sensitivity.
• a zero-to-one transition of the movement detector 1 means that movement has been detected between the successive fields.
• a one-to-one transition means continuous movement between the successive fields.
• a zero-to-zero transition means standstill between the successive fields.
• a one-to-zero transition means a transition from movement to standstill between the successive fields.
• the fields A and B, C and D etc. are merged, the line Bo being introduced between the lines Ao and Ai, the line Bi between the lines Ai and A2 , etc.
• the merged fields are each time repeated once, as represented by arrows at the bottom in Figure 2.
• the fields A and A', B and B' etc. are merged, the line A'o being introduced between the lines Ao and Ai, the line A'l between the lines Ai and A2 , etc.
• the merged fields are each time repeated once or twice, as represented by arrows at the bottom in Figure 4.
• the line Bo is introduced between the lines Ao and Ai , as represented in Figure 2
• the line A'o is introduced, for example, between the lines Ao and A' ⁇ .
• the median filter 1 is therefore solely used for measuring but not for processing.
• the abovementioned information is also relayed, via the median filter 1, to the interpolator 5, so that the interpolation is also performed on the merged fields.
• the result of the interpolation is relayed to the display bank 6.
• the display banks 2 and 6 are read out as described above .
• edges and the details of the video images can be enhanced selectively by a so-called "edge boost" .
• Such an enhancement is performed on the incoming signal by means of two phase-linear "finite impulse response" or FIR filters having a sum of coefficients of 0, the one being a band-pass filter having the coefficients -1 0 2 0 -1 and the other a high-pass filter having the coefficients -1 2 -1.
• the sample frequency is 16 MHz.
• the results of the two filters are merged and scaled, for example divided or multiplied, and added to the original video signal.
• Both filters for example, have eight settings. This allows for various combinations of the two filters.
• the filter effect can be attenuated, if required, to prevent deadlocks .

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• Television Systems (AREA)

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• 1998
  • 1998-09-15 BE BE9800669A patent/BE1012172A5/nl not_active IP Right Cessation
• 1999
  • 1999-09-10 EP EP99969202A patent/EP1114557A1/de not_active Withdrawn
  • 1999-09-10 WO PCT/EP1999/006555 patent/WO2000016561A1/en not_active Ceased
  • 1999-09-10 JP JP2000570975A patent/JP2002525927A/ja active Pending

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