JPH04355581A - Scanning line interpolation circuit - Google Patents
Scanning line interpolation circuitInfo
- Publication number
- JPH04355581A JPH04355581A JP3155369A JP15536991A JPH04355581A JP H04355581 A JPH04355581 A JP H04355581A JP 3155369 A JP3155369 A JP 3155369A JP 15536991 A JP15536991 A JP 15536991A JP H04355581 A JPH04355581 A JP H04355581A
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- JP
- Japan
- Prior art keywords
- interpolation
- value
- pixels
- difference
- directions
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000006243 chemical reaction Methods 0.000 abstract description 19
- 238000009499 grossing Methods 0.000 abstract description 2
- 230000008030 elimination Effects 0.000 abstract 1
- 238000003379 elimination reaction Methods 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 15
- 230000003044 adaptive effect Effects 0.000 description 6
- 238000005070 sampling Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 4
- 230000000750 progressive effect Effects 0.000 description 4
- 230000003111 delayed effect Effects 0.000 description 2
- 206010047571 Visual impairment Diseases 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
Abstract
Description
【０００１】0001
【産業上の利用分野】本発明は、インターレース方式の
テレビジョン信号を順次走査方式のテレビジョン信号に
変換する順次走査変換回路において、補間信号を生成し
て走査線を補間する走査線補間回路に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a scanning line interpolation circuit that generates an interpolation signal to interpolate scanning lines in a progressive scan conversion circuit that converts an interlaced television signal into a progressive scanning television signal. .
【０００２】0002
【従来の技術】現行ＮＴＳＣ放送は走査線数５２５本の
インターレース方式で送られてきている。これは、一画
面を５２５／２本の走査線で２フィールドに分けて送る
ことにより、目の残像現象を利用して５２５本の走査線
に見せているものである。しかし、インターレース走査
には標本化に伴う折り返し歪があり、ラインフリッカが
目立ちやすい。そこで、走査線補間によりこれをノンイ
ンターレースに走査変換すると、ラインフリッカが除去
され、見かけ上垂直解像度が４０％程度向上する。2. Description of the Related Art Current NTSC broadcasting is transmitted using an interlaced system with 525 scanning lines. In this method, one screen is divided into two fields of 525/2 scanning lines and transmitted, thereby making use of the afterimage phenomenon of the eye to make it appear as 525 scanning lines. However, interlaced scanning has aliasing distortion due to sampling, and line flicker is easily noticeable. Therefore, if this is scan-converted to non-interlace by scanning line interpolation, the line flicker is removed and the vertical resolution is apparently improved by about 40%.
【０００３】従来、輝度信号は動き適応走査線補間を行
い、色信号はフィールド内走査線補間を行っている。動
き適応走査線補間とは、動き検出により静止画部と動画
部とを判定し、静止画部では前フィールドの画素をその
まま遅延させて新しい画素とするフィールド間補間を行
い、動画部では上下の画素の平均値を新しい画素とする
フィールド内補間を行う方法である。フィールド間補間
とフィールド内補間の概念をそれぞれ図３（Ａ），（Ｂ
）に示す。色信号をフィールド内走査線補間にしている
理由は、フィールドメモリが高価なことと、色信号の解
像度は低いので、適応処理しても画質にほとんど差がで
ないためである。Conventionally, luminance signals are subjected to motion-adaptive scanning line interpolation, and color signals are subjected to intra-field scanning line interpolation. Motion-adaptive scan line interpolation uses motion detection to determine whether it is a still image or a moving image. In the still image, interfield interpolation is performed in which the pixels of the previous field are delayed as they are to create new pixels, and in the moving image, the upper and lower pixels are This is a method of performing intra-field interpolation in which the average value of pixels is used as a new pixel. The concepts of inter-field interpolation and intra-field interpolation are shown in Figures 3 (A) and (B), respectively.
). The reason why the color signal is subjected to intra-field scanning line interpolation is that field memory is expensive and the resolution of the color signal is low, so there is almost no difference in image quality even with adaptive processing.
【０００４】現行走査線補間において、輝度信号の動き
適応走査線補間には、静止画部と動画部とで画質差が大
きく違和感があるという問題点がある。静止画部におい
ては、過去のフィールドの画素が使えるので垂直方向の
サンプリングは５２５本である。従ってサンプリング定
理により、垂直方向の周波数５２５／２ｃｐｈ （ｃｙ
ｃｌｅｐｅｒ ｈｅｉｇｈｔ）までは再現することがで
きる。しかし、５２５／２ｃｐｈ 以上の周波数は低域
に折り返り、正しく再生することはできない。動画部に
おいては、同じフィールドの画素しか使えないため、垂
直方向のサンプリングは５２５／２本である。ゆえにこ
の場合は、５２５／４ｃｐｈ の周波数までしか再現す
ることができない。この静止画部５２５／２ｃｐｈ 、
動画部５２５／４ｃｐｈ の垂直解像度の違いが動画部
と静止画部の画質差になってしまう。
そして、サンプリング周波数が異なるため、この動画部
と静止画部の垂直解像度の違いを改善することは、本質
的には不可能である。[0004] In the current scanning line interpolation, motion adaptive scanning line interpolation of luminance signals has a problem in that there is a large difference in image quality between the still image portion and the moving image portion, which gives an unnatural feeling. In the still image portion, since pixels of past fields can be used, the number of vertical samplings is 525. Therefore, according to the sampling theorem, the vertical frequency is 525/2 cph (cy
cleper height). However, frequencies above 525/2 cph fold back into the low range and cannot be reproduced correctly. In the moving image part, since only pixels in the same field can be used, the sampling in the vertical direction is 525/2 lines. Therefore, in this case, only frequencies up to 525/4 cph can be reproduced. This still image part 525/2cph,
The difference in vertical resolution of the moving image section 525/4 cph results in a difference in image quality between the moving image section and the still image section. Since the sampling frequencies are different, it is essentially impossible to improve the difference in vertical resolution between the moving image portion and the still image portion.
【０００５】一方、現行フィールド内補間では、上下の
画素の平均値を補間画素としている。これは［１／２
１ １／２］の補間フィルタを挿入したことになる
。図４はフィールド内補間フィルタの周波数特性を示す
図である。図４において、鉛直方向はゲインを示してい
る。
この図４に示すように、５２５／４ｃｐｈ でゲイン１
／２、５２５／２ｃｐｈ でゲイン０になる。即ち、動
画部では垂直周波数５２５／４ｃｐｈ 近傍が減衰して
いることになる。従って、現行走査線補間において、動
画部と静止画部の画質差はさらに大きいものとなってい
る。On the other hand, in the current intra-field interpolation, the average value of the upper and lower pixels is used as the interpolated pixel. This is [1/2
This means that an interpolation filter of 1 1/2] has been inserted. FIG. 4 is a diagram showing the frequency characteristics of the intra-field interpolation filter. In FIG. 4, the vertical direction indicates gain. As shown in Figure 4, the gain is 1 at 525/4 cph.
/2, 525/2cph has a gain of 0. That is, in the moving image portion, the vertical frequency near 525/4 cph is attenuated. Therefore, in the current scanning line interpolation, the difference in image quality between the moving image portion and the still image portion is even larger.
【０００６】上記走査線補間において、動画部の処理で
あるフィールド内補間の斜め解像度を改善することによ
って、静止画部と動画部の違和感を少なくする方法が検
討されている。即ち、フィールド内の補間方向を、垂直
方向のみならず複数の斜め方向の補間にまで拡張した２
次元適応走査線補間にすることにより、動画部と静止画
部の画質差を少なくしたものである。画像が完全な水平
線の場合は斜め方向の補間はできないが、実際の映像は
完全に垂直周波数成分のみの場合は少なく、斜め方向の
成分が多い。従って、２次元適応走査線補間で斜め解像
度を改善することによって、大幅な画質改善ができると
考えられる。In the above-mentioned scanning line interpolation, methods are being considered to reduce the sense of incongruity between the still image section and the moving image section by improving the diagonal resolution of intra-field interpolation, which is a process for the moving image section. In other words, the interpolation direction within the field is extended not only to the vertical direction but also to interpolation in multiple diagonal directions.
By using dimension-adaptive scanning line interpolation, the difference in image quality between the moving image portion and the still image portion is reduced. If the image is a completely horizontal line, interpolation in the diagonal direction is not possible, but actual images rarely contain only vertical frequency components, and there are many components in the diagonal direction. Therefore, it is considered that image quality can be significantly improved by improving the diagonal resolution using two-dimensional adaptive scanning line interpolation.
【０００７】図２は上述した２次元適応走査線補間回路
を示すブロック図である。そして、従来の２次元適応走
査線補間回路について図５と併せて説明する。図２にお
いて、入力端子１よりテレビジョン信号（輝度信号）が
入力し、ラインメモリ（Ｈ）２及び斜めフィルタ３に供
給される。ラインメモリ２に入力された信号は１水平走
査期間（１Ｈ）遅延されて斜めフィルタ３に入力される
。ここで、斜めフィルタ３は、図５（Ａ）に示すように
、２つの斜め右方向，垂直方向，２つの斜め左方向の計
５つの方向の画素よりそれぞれ平均値をとって補間画素
値Ａ〜Ｅを生成する。さらにまた、斜めフィルタ３は、
図５（Ｂ）に示すように、２つの斜め右方向，垂直方向
，２つの斜め左方向の計５つの方向の画素よりそれぞれ
差分値Ｄａ〜Ｄｅを生成する。FIG. 2 is a block diagram showing the above-mentioned two-dimensional adaptive scanning line interpolation circuit. Next, a conventional two-dimensional adaptive scanning line interpolation circuit will be explained in conjunction with FIG. 5. In FIG. 2, a television signal (luminance signal) is input from an input terminal 1 and is supplied to a line memory (H) 2 and a diagonal filter 3. The signal input to the line memory 2 is delayed by one horizontal scanning period (1H) and input to the diagonal filter 3. Here, as shown in FIG. 5A, the diagonal filter 3 calculates the average value of pixels in a total of five directions: two diagonally right directions, a vertical direction, and two diagonally left directions, and calculates an interpolated pixel value A. ~E is generated. Furthermore, the oblique filter 3 is
As shown in FIG. 5B, difference values Da to De are generated from pixels in a total of five directions: two diagonally right directions, a vertical direction, and two diagonally left directions.
【０００８】そして、差分値Ｄａ〜Ｄｅは補間方向判定
回路４に入力され、補間画素値Ａ〜Ｅはセレクタ５に入
力される。補間方向判定回路４は最も相関の強い方向、
即ち差分値Ｄａ〜Ｄｅの中で最も値の小さい方向が最も
相関の強い方向と判定し、その方向の制御信号Ｓをセレ
クタ５に出力する。セレクタ５は制御信号で指示された
方向の補間画素値をＡ〜Ｅの中から選択し、フィールド
内の補間値として出力端子６より出力する。The difference values Da to De are input to an interpolation direction determining circuit 4, and the interpolation pixel values A to E are input to a selector 5. The interpolation direction determination circuit 4 selects the direction with the strongest correlation,
That is, the direction with the smallest value among the difference values Da to De is determined to be the direction with the strongest correlation, and the control signal S in that direction is output to the selector 5. The selector 5 selects an interpolated pixel value from A to E in the direction specified by the control signal, and outputs it from the output terminal 6 as an interpolated value within the field.
【０００９】図５（Ｃ）のように縦線のエッジ部分の場
合、差分値Ｄｃが最も小さい値となる。従って、補間値
として補間画素値Ｃを選択する。次に、図５（Ｄ）のよ
うに斜め線のエッジ部分の場合、差分値Ｄｄが最も小さ
い値になり、補間値として補間画素値Ｄを選択する。ま
た、図５（Ｅ）のようさらに斜めになった線のエッジ部
分の場合、差分値Ｄｅが最も小さい値になり、補間値と
して補間画素値Ｅを選択する。図５（Ｆ）のように横線
のエッジ部分の場合、差分値Ｄａ〜Ｄｅのどの値も大き
くなり、このときは斜めの補間はせず補間画素値Ｃを選
択する。このようにして、補間方向を判定し走査線補間
することによって、斜め方向を中心とした広範囲の解像
度劣化を改善することができる。In the case of an edge portion of a vertical line as shown in FIG. 5(C), the difference value Dc is the smallest value. Therefore, the interpolated pixel value C is selected as the interpolated value. Next, in the case of the edge portion of the diagonal line as shown in FIG. 5(D), the difference value Dd becomes the smallest value, and the interpolated pixel value D is selected as the interpolated value. Further, in the case of an edge portion of a line that is more oblique as shown in FIG. 5(E), the difference value De becomes the smallest value, and the interpolated pixel value E is selected as the interpolated value. In the case of an edge portion of a horizontal line as shown in FIG. 5(F), all of the difference values Da to De are large, and in this case, interpolation pixel value C is selected without diagonal interpolation. In this way, by determining the interpolation direction and performing scanning line interpolation, it is possible to improve resolution deterioration over a wide range centered on diagonal directions.
【００１０】0010
【発明が解決しようとする課題】しかしながら、上述し
た図５（Ｃ）〜（Ｆ）に示すような水平方向の周波数が
低い斜め線の場合はほとんど問題ないが、図５（Ｇ）に
示すような水平方向の周波数が高い斜め線（即ち、細い
斜め線）の場合は以下のような問題点を有している。図
５（Ｇ）において、補間画素値Ａの差分値Ｄａと補間画
素値Ｄの差分値Ｄｄは共に小さい値となる。ここで、補
間画素値Ｄを選択するのが正しいが、このとき補間画素
値Ａを選択すれば完全に誤補間となり、画質を著しく劣
化させることになる。このように、補間画素を生成する
場合、どの方向から補間すべきかの判定が難しく、従来
の２次元適応走査線補間回路においては、誤補間を起こ
すという問題点があった。それゆえ、本発明は補間画素
を生成するにあたり誤補間を起こさない走査線補間回路
を提供することを目的とする。[Problems to be Solved by the Invention] However, there is almost no problem in the case of diagonal lines with low horizontal frequencies as shown in FIGS. 5(C) to 5(F), but as shown in FIG. 5(G), A diagonal line (that is, a thin diagonal line) with a high frequency in the horizontal direction has the following problems. In FIG. 5(G), the difference value Da of the interpolated pixel value A and the difference value Dd of the interpolated pixel value D are both small values. Here, it is correct to select the interpolated pixel value D, but if the interpolated pixel value A is selected at this time, it will result in completely incorrect interpolation, and the image quality will deteriorate significantly. As described above, when generating interpolated pixels, it is difficult to determine from which direction interpolation should be performed, and conventional two-dimensional adaptive scanning line interpolation circuits have the problem of causing erroneous interpolation. Therefore, an object of the present invention is to provide a scanning line interpolation circuit that does not cause erroneous interpolation when generating interpolated pixels.
【００１１】[0011]
【課題を解決するための手段】本発明は、上述した従来
の技術の課題を解決するため、内挿される補間画素を中
心とする垂直方向、複数の斜め右方向、複数の斜め左方
向の複数の方向の画素それぞれの平均値をとり補間画素
値を生成する補間画素値生成手段と、前記複数の方向の
画素それぞれの差分値を生成する差分値生成手段と、前
記それぞれの差分値が入力され、最も相関の強い方向を
判定する補間方向判定手段と、前記それぞれの補間画素
値が入力され、前記補間方向判定手段より出力される制
御信号により前記それぞれの補間画素値を選択して出力
する選択手段とよりなる、インターレースされたテレビ
ジョン信号を順次走査に変換するための走査線補間回路
であって、前記補間方向判定手段は、前記垂直方向の画
素の差分値が入力され、この差分値を水平方向高域周波
数において略０として出力する水平方向ローパスフィル
タと、前記複数の斜め右方向及び複数の斜め左方向の画
素の差分値と前記水平方向ローパスフィルタより出力さ
れた前記垂直方向の画素の差分値それぞれを、絶対値化
する絶対値化手段と、前記絶対値化手段の出力が供給さ
れ、前記複数の方向の差分値を比較する比較手段とを有
して構成されることを特徴とする走査線補間回路を提供
するものである。[Means for Solving the Problems] In order to solve the problems of the prior art described above, the present invention provides a plurality of vertical directions, a plurality of diagonal right directions, and a plurality of diagonal left directions centered on the interpolation pixel to be interpolated. an interpolated pixel value generation means for generating an interpolated pixel value by taking an average value of each pixel in the direction; a difference value generation means for generating a difference value for each of the pixels in the plurality of directions; , an interpolation direction determining means for determining the direction with the strongest correlation; and a selection for receiving the respective interpolated pixel values and selecting and outputting the respective interpolated pixel values based on a control signal output from the interpolating direction determining means. a scanning line interpolation circuit for converting an interlaced television signal into a sequential scan signal, the interpolation direction determining means receiving a difference value of pixels in the vertical direction and determining the difference value. A horizontal low-pass filter that outputs approximately 0 at a horizontal high frequency, a difference value between the plurality of diagonally right-directed pixels and a plurality of diagonally left-directed pixels, and the vertical pixel output from the horizontal low-pass filter. It is characterized by comprising an absolute value conversion means for converting each difference value into an absolute value, and a comparison means to which the output of the absolute value conversion means is supplied and for comparing the difference values in the plurality of directions. The present invention provides a scanning line interpolation circuit that performs the following steps.
【００１２】0012
【実施例】以下、本発明の走査線補間回路について、添
付図面を参照して説明する。図１は本発明となる走査線
補間回路における補間方向判定回路（図２中の補間方向
判定回路４）を示すブロック図である。図６〜図１０は
それぞれ差分値Ｄａ〜Ｄｄの周波数特性を示す図、図１
１は本発明を説明するための周波数特性を示す図である
。なお、本発明の走査線補間回路においては、補間方向
判定回路のみ従来と相違している。それゆえ補間方向判
定回路について詳細に説明し、その他の部分の説明は省
略する。DESCRIPTION OF THE PREFERRED EMBODIMENTS A scanning line interpolation circuit according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing an interpolation direction determination circuit (interpolation direction determination circuit 4 in FIG. 2) in a scanning line interpolation circuit according to the present invention. 6 to 10 are diagrams showing the frequency characteristics of the difference values Da to Dd, respectively, and FIG.
1 is a diagram showing frequency characteristics for explaining the present invention. The scanning line interpolation circuit of the present invention is different from the conventional one only in the interpolation direction determination circuit. Therefore, the interpolation direction determination circuit will be explained in detail, and the explanation of other parts will be omitted.
【００１３】図１において、斜めフィルタ３より出力す
る差分値Ｄａ，Ｄｂ，Ｄｄ，Ｄｅはそれぞれ絶対値化ノ
ンリニア変換回路（ＡＢＳＮＬ）１２，１３，１５，１
６に入力される。差分値Ｄｃは水平方向ローパスフィル
タ（ＨＬＰＦ）１１に入力され、水平方向の高い周波数
においてその値を略０とされた後、絶対値化ノンリニア
変換回路１４に入力される。ここで、絶対値化ノンリニ
ア変換回路１２〜１６は差分値Ｄａ〜Ｄｅを絶対値化し
、ノンリニア変換によるリミッタ処理をする。そして、
各絶対値化ノンリニア変換回路１２〜１６の出力はロー
パスフィルタ（ＬＰＦ）１７〜２１に入力され、ノイズ
除去とスムージングが行われる。そして、ローパスフィ
ルタ１７〜２１の出力は比較回路２２に入力される。比
較回路２２はローパスフィルタ１７〜２１の出力を比較
し、最も値の小さい方向が最も相関が強いとしてその方
向の制御信号Ｓを出力する。In FIG. 1, the difference values Da, Db, Dd, and De outputted from the diagonal filter 3 are outputted by absolute value nonlinear conversion circuits (ABSNL) 12, 13, 15, and 1, respectively.
6 is input. The difference value Dc is input to a horizontal low-pass filter (HLPF) 11, and after its value is reduced to approximately 0 at high frequencies in the horizontal direction, it is input to an absolute value nonlinear conversion circuit 14. Here, the absolute value nonlinear conversion circuits 12 to 16 convert the difference values Da to De to absolute values, and perform limiter processing by nonlinear conversion. and,
The outputs of the absolute value nonlinear conversion circuits 12 to 16 are input to low pass filters (LPFs) 17 to 21, where they are subjected to noise removal and smoothing. The outputs of the low-pass filters 17 to 21 are then input to a comparison circuit 22. The comparison circuit 22 compares the outputs of the low-pass filters 17 to 21, determines that the direction with the smallest value has the strongest correlation, and outputs the control signal S in that direction.
【００１４】なお、本実施例においては、上記のように
、絶対値化ノンリニア変換回路１２〜１６によってノン
リニア変換を行ってビット数を下げている。これは差分
値Ｄａ〜Ｄｅの大きさを比較するにはそれほどのビット
数は必要がないからである。従って、このノンリニア変
換は必ずしも必要ではない。また、絶対値化ノンリニア
変換回路１２〜１６の出力にノイズが少ない場合、ロー
パスフィルタ１７〜２１は必ずしも必要ではない。In this embodiment, as described above, the absolute value conversion nonlinear conversion circuits 12 to 16 perform nonlinear conversion to reduce the number of bits. This is because a large number of bits is not required to compare the magnitudes of the difference values Da to De. Therefore, this nonlinear conversion is not necessarily necessary. Further, when the outputs of the absolute value conversion nonlinear conversion circuits 12 to 16 have little noise, the low pass filters 17 to 21 are not necessarily necessary.
【００１５】次に、図６〜図１１を用いてさらに説明す
る。図６〜図１１において、鉛直方向はゲインを示して
いる。差分値Ｄａ〜Ｄｅの周波数特性は図６〜図１０に
示す如くであり、ゲイン０となる周波数付近で相関が強
いとして、その方向が選択される。この直線状になって
いるゲイン０の周波数部分のうち、水平０Ｈｚ垂直０ｃ
ｐｈ の点を通る部分は正しい判定となるが、この点を
通らない部分は折り返し周波数であり、すべて誤補間の
判定となる。例えば、図９の差分値Ｄｄについて説明す
ると、Ａ−Ａ′間の周波数とＣ−Ｃ′間の周波数は誤補
間の判定であり、Ｂ−Ｂ′間の周波数は正しい判定であ
る。この周波数特性より明らかなように、差分値を生成
する斜めフィルタ３に折り返しの起きる水平方向の高い
周波数では誤補間になる。それゆえ、図８に示す差分値
Ｄｃのみ水平方向ローパスフィルタ１１を通すことによ
り、図１１に示す如く水平方向の高い周波数では差分値
Ｄｃの値を０近くまで落とす。これにより垂直方向の補
間値である補間画素値Ｃを優先的に選択するようにする
ものである。Next, further explanation will be given using FIGS. 6 to 11. In FIGS. 6 to 11, the vertical direction indicates gain. The frequency characteristics of the difference values Da to De are as shown in FIGS. 6 to 10, and since the correlation is strong near the frequency where the gain is 0, that direction is selected. Among this linear frequency part of gain 0, horizontal 0Hz and vertical 0c
The part that passes through the point ph will be judged as correct, but the part that does not pass through this point is the aliasing frequency, and all will be judged as incorrect interpolation. For example, regarding the difference value Dd in FIG. 9, the frequency between A and A' and the frequency between C and C' are determined to be incorrect interpolation, and the frequency between B and B' is determined to be correct. As is clear from this frequency characteristic, erroneous interpolation occurs at high frequencies in the horizontal direction where aliasing occurs in the diagonal filter 3 that generates the difference value. Therefore, by passing only the difference value Dc shown in FIG. 8 through the horizontal low-pass filter 11, the value of the difference value Dc is reduced to nearly 0 at high frequencies in the horizontal direction as shown in FIG. This allows the interpolated pixel value C, which is the interpolated value in the vertical direction, to be selected preferentially.
【００１６】なお、本実施例においては、内挿される補
間画素を中心とする垂直方向、２つの斜め右方向、２つ
の斜め左方向の計５つの方向の画素より補間信号を生成
して走査線を補間する場合について示しているが、垂直
方向、１つの斜め右方向、１つの斜め左方向の計３つの
方向の画素、あるいは、垂直方向、３つの斜め右方向、
３つの斜め左方向の計７つの方向の画素より補間信号を
生成してもよく、本発明は上述した実施例に限定される
ことはない。このように、本発明は、本発明の要旨を逸
脱しない範囲において種々の変更が可能である。In this embodiment, interpolation signals are generated from pixels in a total of five directions, including the vertical direction, two diagonal right directions, and two diagonal left directions centering on the interpolation pixel to be interpolated, and the scanning line is This example shows the case where pixels are interpolated in three directions: vertically, one diagonally to the right, and one diagonally to the left, or pixels in the vertical direction, three diagonally to the right,
Interpolation signals may be generated from pixels in a total of seven directions, including three diagonally to the left, and the present invention is not limited to the embodiments described above. As described above, the present invention can be modified in various ways without departing from the gist of the present invention.
【００１７】[0017]
【発明の効果】以上詳細に説明したように、本発明の走
査線補間回路は上述の如く構成されてなるので、水平方
向の周波数が高い斜め線の絵柄においても誤補間を起こ
すことがない。それゆえ画質劣化を生じることなく走査
線を補間することができる。また、本発明の走査線補間
回路を順次走査変換回路に用いれば、動画部と静止画部
で画質の差がなく、違和感のない順次走査変換回路を提
供することができるという実用上極めて優れた効果があ
る。As described in detail above, since the scanning line interpolation circuit of the present invention is constructed as described above, erroneous interpolation does not occur even in a diagonal line pattern with a high frequency in the horizontal direction. Therefore, scanning lines can be interpolated without deteriorating image quality. Further, if the scanning line interpolation circuit of the present invention is used in a progressive scan conversion circuit, there is no difference in image quality between the moving image section and the still image section, and it is possible to provide a progressive scan conversion circuit that does not give an unnatural feeling. effective.
【図１】本発明の走査線補間回路中の補間方向判定回路
の一実施例を示す部分ブロック図である。FIG. 1 is a partial block diagram showing an embodiment of an interpolation direction determination circuit in a scanning line interpolation circuit of the present invention.
【図２】走査線補間回路の全体を示すブロック図である
。FIG. 2 is a block diagram showing the entire scanning line interpolation circuit.
【図３】従来の走査線補間について説明する図である。FIG. 3 is a diagram illustrating conventional scanning line interpolation.
【図４】フィールド内補間フィルタの周波数特性を示す
図である。FIG. 4 is a diagram showing frequency characteristics of an intra-field interpolation filter.
【図５】従来の走査線補間について説明する図である。FIG. 5 is a diagram illustrating conventional scanning line interpolation.
【図６】差分値Ｄａの周波数特性を示す図である。FIG. 6 is a diagram showing the frequency characteristics of the difference value Da.
【図７】差分値Ｄｂの周波数特性を示す図である。FIG. 7 is a diagram showing frequency characteristics of the difference value Db.
【図８】差分値Ｄｃの周波数特性を示す図である。FIG. 8 is a diagram showing the frequency characteristics of the difference value Dc.
【図９】差分値Ｄｄの周波数特性を示す図である。FIG. 9 is a diagram showing frequency characteristics of the difference value Dd.
【図１０】差分値Ｄｅの周波数特性を示す図である。FIG. 10 is a diagram showing frequency characteristics of the difference value De.
【図１１】水平方向ローパスフィルタを通した差分値Ｄ
ｃの周波数特性を示す図である。[Figure 11] Difference value D passed through a horizontal low-pass filter
It is a figure which shows the frequency characteristic of c.
１ 入力端子
２ ラインメモリ
３ 斜めフィルタ
４ 補間方向判定回路
５ セレクタ
６ 出力端子
１１ 水平方向ローパスフィルタ
１２〜１６ 絶対値化ノンリニア変換回路１７〜２１
ローパスフィルタ
２２ 比較回路1 Input terminal 2 Line memory 3 Diagonal filter 4 Interpolation direction determination circuit 5 Selector 6 Output terminal 11 Horizontal low-pass filters 12 to 16 Absolute value nonlinear conversion circuits 17 to 21
Low-pass filter 22 Comparison circuit
Claims (1)
、複数の斜め右方向、複数の斜め左方向の複数の方向の
画素それぞれの平均値をとり補間画素値を生成する補間
画素値生成手段と、前記複数の方向の画素それぞれの差
分値を生成する差分値生成手段と、前記それぞれの差分
値が入力され、最も相関の強い方向を判定する補間方向
判定手段と、前記それぞれの補間画素値が入力され、前
記補間方向判定手段より出力される制御信号により前記
それぞれの補間画素値を選択して出力する選択手段とよ
りなる、インターレースされたテレビジョン信号を順次
走査に変換するための走査線補間回路であって、前記補
間方向判定手段は、前記垂直方向の画素の差分値が入力
され、この差分値を水平方向高域周波数において略０と
して出力する水平方向ローパスフィルタと、前記複数の
斜め右方向及び複数の斜め左方向の画素の差分値と前記
水平方向ローパスフィルタより出力された前記垂直方向
の画素の差分値それぞれを、絶対値化する絶対値化手段
と、前記絶対値化手段の出力が供給され、前記複数の方
向の差分値を比較する比較手段とを有して構成されるこ
とを特徴とする走査線補間回路。[Claim 1] Interpolation pixel value generation that generates an interpolation pixel value by taking the average value of each pixel in a plurality of directions, such as a vertical direction, a plurality of diagonal right directions, and a plurality of diagonal left directions, centering on the interpolation pixel to be interpolated. means, a difference value generation means for generating difference values for each of the pixels in the plurality of directions, an interpolation direction determination means for receiving the respective difference values and determining a direction with the strongest correlation, and each of the interpolation pixels. A scanning device for converting an interlaced television signal into sequential scanning, comprising a selection device that receives a value and selects and outputs each of the interpolated pixel values based on a control signal output from the interpolation direction determining device. In the line interpolation circuit, the interpolation direction determining means includes a horizontal low-pass filter that receives the difference value of the pixels in the vertical direction and outputs the difference value as approximately 0 at a high frequency in the horizontal direction; Absolute value converting means for converting into absolute values each of the difference values of the pixels in the diagonally right direction and the plurality of pixels in the diagonally left direction and the difference values of the pixels in the vertical direction output from the horizontal low-pass filter; and the absolute value converting means. 1. A scanning line interpolation circuit comprising: comparison means to which an output of is supplied, and comparing means for comparing difference values in the plurality of directions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3155369A JP2580891B2 (en) | 1991-05-31 | 1991-05-31 | Scan line interpolation circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3155369A JP2580891B2 (en) | 1991-05-31 | 1991-05-31 | Scan line interpolation circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH04355581A true JPH04355581A (en) | 1992-12-09 |
| JP2580891B2 JP2580891B2 (en) | 1997-02-12 |
Family
ID=15604426
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3155369A Expired - Lifetime JP2580891B2 (en) | 1991-05-31 | 1991-05-31 | Scan line interpolation circuit |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2580891B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009005120A1 (en) | 2007-07-03 | 2009-01-08 | Nec Corporation | Image interpolation method, image interpolation device, and program |
| US8497938B2 (en) | 2008-03-21 | 2013-07-30 | Nec Corporation | Image processing method, image processing apparatus and image processing program |
| US8698954B2 (en) | 2008-03-21 | 2014-04-15 | Nec Corporation | Image processing method, image processing apparatus and image processing program |
-
1991
- 1991-05-31 JP JP3155369A patent/JP2580891B2/en not_active Expired - Lifetime
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2009005120A1 (en) | 2007-07-03 | 2009-01-08 | Nec Corporation | Image interpolation method, image interpolation device, and program |
| US8565556B2 (en) | 2007-07-03 | 2013-10-22 | Nec Corporation | Image interpolation method, image interpolation device, and program |
| US8497938B2 (en) | 2008-03-21 | 2013-07-30 | Nec Corporation | Image processing method, image processing apparatus and image processing program |
| US8698954B2 (en) | 2008-03-21 | 2014-04-15 | Nec Corporation | Image processing method, image processing apparatus and image processing program |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2580891B2 (en) | 1997-02-12 |
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