JPH0134420B2 - - Google Patents
Info
- Publication number
- JPH0134420B2 JPH0134420B2 JP56197342A JP19734281A JPH0134420B2 JP H0134420 B2 JPH0134420 B2 JP H0134420B2 JP 56197342 A JP56197342 A JP 56197342A JP 19734281 A JP19734281 A JP 19734281A JP H0134420 B2 JPH0134420 B2 JP H0134420B2
- Authority
- JP
- Japan
- Prior art keywords
- level difference
- pixel
- signal
- image signal
- memory
- 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.)
- Expired
Links
- 238000007796 conventional method Methods 0.000 description 5
- 238000010586 diagram Methods 0.000 description 4
- 238000000034 method Methods 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 239000012141 concentrate Substances 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/41—Bandwidth or redundancy reduction
Description
【発明の詳細な説明】
この発明は中間調を有する多階調画像信号を高
効率に符号化（あるいは復合化）する画像信号符
号化装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image signal encoding device that highly efficiently encodes (or decodes) a multi-gradation image signal having halftones.
従来の中間調画像信号の符号化方式としてよく
行われていたものは、同一走査線上のすぐ左すな
わち直前画素とのレベル差を検出しこれを２値信
号に変換し、符号化するものであつた。 The conventional encoding method for halftone image signals is to detect the level difference between the pixel and the immediately left pixel, that is, the immediately preceding pixel, on the same scanning line, convert it into a binary signal, and encode it. Ta.
第１図はこの従来方式のブロツク図の例であ
る。以下にその簡単な動作原理を述べる。走査入
力される画像信号の各画素信号（注目画素xiとす
る）は、１画素メモリ１で１画素分遅延された画
素すなわち注目画素xiの直前画素xi-1とのレベル
差を減算器２によつて求め、これを符号器３によ
つて符号化する。一方、受信側ではこの符号化信
号を復合器４によつてレベル差信号に復合化し、
これを１画素メモリ５に蓄えられた直前画素xi-1
の画素レベルを加えて注目画素信号xiを得る。
尚、この時符号器３によつてレベル差信号の近似
値を符号化する時は、１の１画素メモリ１に、入
力された近似差信号に対応した画素レベルを修正
して書き込む手法がとられる。 FIG. 1 is an example of a block diagram of this conventional method. The simple operating principle is described below. Each pixel signal of the scanned input image signal (referred to as the pixel of interest xi) is stored in a subtracter 2 using the level difference between the pixel delayed by one pixel in the pixel memory 1, that is, the pixel xi -1 immediately before the pixel of interest xi. This is then encoded by the encoder 3. On the other hand, on the receiving side, this encoded signal is decoded into a level difference signal by a decoder 4,
This is the previous pixel xi -1 stored in the pixel memory 5.
By adding the pixel level of , the target pixel signal xi is obtained.
At this time, when the encoder 3 encodes the approximate value of the level difference signal, a method is to correct and write the pixel level corresponding to the input approximate difference signal into the 1-pixel memory 1. It will be done.
ところで、この従来方式においては同一走査上
の隣接画素とのレベル差をとることにより、その
レベル差信号を０付近に集中させることが可能で
あるが、連続するレベル差信号間の相関は弱いも
のであつた。 By the way, in this conventional method, by taking the level difference between adjacent pixels on the same scan, it is possible to concentrate the level difference signal around 0, but the correlation between successive level difference signals is weak. It was hot.
この発明は、上記のような従来の欠点を除去す
るためになされたもので、１ライン分の画素メモ
リを設け、このメモリに記憶された１ライン分の
画像信号と次走査入力される注目画像信号の各対
応画素とのレベル差をとり、これを符号化すると
共に走査方向の相関を除去する符号器を用いるこ
とにより、レベル差信号間の相関を強くできると
共に高効率伝送ができる画像符号化装置を提供す
るものである。 This invention was made in order to eliminate the above-mentioned drawbacks of the conventional art, and includes a pixel memory for one line, and a pixel memory for one line stored in this memory and an image of interest to be input for the next scan. Image encoding that can strengthen the correlation between level difference signals and enable highly efficient transmission by using an encoder that takes the level difference between the signal and each corresponding pixel, encodes it, and removes the correlation in the scanning direction. It provides equipment.
以下、この発明の一実施例を図を用いて説明す
る。第２図において、従来の第１図と異なる点は
１画素メモリ１および６を１ラインメモリ１１お
よび１６に、また符号器３、復合器４をランレン
グス符号器１３、ランレングス復合器１４に置換
えた点である。 An embodiment of the present invention will be described below with reference to the drawings. In FIG. 2, the difference from the conventional FIG. This is the point that was replaced.
次に第３図に示す画像信号例をあげて第２図の
動作を説明する。第３図は画像信号のレベルが０
から４迄５通りある場合の例である。したがつて
この場合、レベル差信号は−４から４迄分布する
が、レベル差信号がマイナスの時は５を加えて必
ず０から４迄分布するようにする。なお、この処
理を行つても受信側では一意に復合できる。a1，
a2は＃１ライン、＃２ラインの従来方式によるレ
ベル差信号、b1，b2はこの発明によるレベル差信
号である。符号として第４図の形式を想定すると
＃１ラインの従来方式による符号語列はc1のよう
に計13ビツト、＃２ラインの従来方式による符号
語列はc2のようにやはり計13ビツトとなる。 Next, the operation of FIG. 2 will be explained using the example of the image signal shown in FIG. In Figure 3, the level of the image signal is 0.
This is an example where there are 5 ways from 4 to 4. Therefore, in this case, the level difference signal is distributed from -4 to 4, but when the level difference signal is negative, 5 is added to ensure that it is distributed from 0 to 4. Note that even if this processing is performed, the data can be uniquely decoded on the receiving side. a 1 ,
a 2 is a level difference signal of the #1 line and #2 line according to the conventional method, and b 1 and b 2 are level difference signals according to the present invention. Assuming the format shown in Figure 4 as the code, the code word string of the #1 line using the conventional method is a total of 13 bits, such as c1 , and the code word string of the #2 line using the conventional method is also a total of 13 bits, such as c2 . becomes.
この実施例では第５図に示すようなランレング
ス符号を採用し、第４図の符号によつてレベル差
信号を符号化した直後に、そのレベル差信号の続
く長さ、即ちランレングスを符号化する。符号と
して、例えば第５図のようなものを用いると＃１
ラインの符号語列はd1のように計10ビツト＃２ラ
インの符号語列はd2のように計12ビツトとなり、
従来のものに比べ計４ビツトの減少が図れる。 In this embodiment, a run length code as shown in FIG. 5 is adopted, and immediately after the level difference signal is encoded using the code in FIG. 4, the length of the level difference signal, that is, the run length is encoded. become For example, if you use the code shown in Figure 5, #1
The code word string for the line is 10 bits in total, such as d1.The code word string for #2 line is 12 bits in total, such as d2 .
A total of 4 bits can be reduced compared to the conventional one.
この発明は上記実施例で示した画像信号に限ら
ず、周期性あるいは走査入力される信号に対して
も同様に適用できることはいうまでもない。 It goes without saying that the present invention is not limited to the image signals shown in the above embodiments, but can be similarly applied to periodic or scanned input signals.
以上のように、この発明によればレベル差信号
の走査方向すなわち水平方向の相関が強めること
ができ、また水平方向の相関を除去できるランレ
ングス符号器により、符号長を短かくでき、極め
て伝送時間を短かくすることができる。 As described above, according to the present invention, the correlation in the scanning direction, that is, the horizontal direction, of level difference signals can be strengthened, and the code length can be shortened by using a run-length encoder that can remove the correlation in the horizontal direction. time can be shortened.
第１図は従来装置のブロツク図、第２図はこの
発明の一実施例による画像信号符号化復合化装置
を示すブロツク図、第３図〜第５図は第１図およ
び第２図の動作を説明するための画像信号例およ
び符号語列を示す図である。
図中、２は加算器、５は減算器、１１および２
１は１ラインメモリ、１３および１４はランレン
グス符号器およびランレングス復合器である。な
お、図中同一符号は同一又は相当部分を示す。
FIG. 1 is a block diagram of a conventional device, FIG. 2 is a block diagram showing an image signal encoding/decoding device according to an embodiment of the present invention, and FIGS. 3 to 5 show the operation of FIGS. 1 and 2. FIG. 2 is a diagram showing an example of an image signal and a code word string for explaining the above. In the figure, 2 is an adder, 5 is a subtracter, 11 and 2
1 is a 1-line memory, and 13 and 14 are a run-length encoder and a run-length decoder. Note that the same reference numerals in the figures indicate the same or equivalent parts.
Claims (1)
信号を少なくとも１走査線分記憶するメモリ、こ
のメモリに記憶された画像信号と次走査入力され
る画像信号との各対応画素のレベル差をそれぞれ
減算出力する減算器、及びこの減算器より出力さ
れるレベル差信号をランレングス符号化するラン
レングス符号器を備えたことを特徴とする画像符
号化装置。1. A memory that stores at least one scanning line of an image signal that is quantized to a 2 m level and is scanned and input, and a level difference of each corresponding pixel between the image signal stored in this memory and the image signal that is input for the next scan. An image encoding device comprising: a subtracter that outputs a subtraction value; and a run-length encoder that performs run-length encoding of a level difference signal output from the subtracter.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56197342A JPS5897965A (en) | 1981-12-07 | 1981-12-07 | Picture encoding device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP56197342A JPS5897965A (en) | 1981-12-07 | 1981-12-07 | Picture encoding device |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5897965A JPS5897965A (en) | 1983-06-10 |
| JPH0134420B2 true JPH0134420B2 (en) | 1989-07-19 |
Family
ID=16372872
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP56197342A Granted JPS5897965A (en) | 1981-12-07 | 1981-12-07 | Picture encoding device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5897965A (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55124361A (en) * | 1979-03-19 | 1980-09-25 | Nippon Telegr & Teleph Corp <Ntt> | Redundancy suppression coding system |
-
1981
- 1981-12-07 JP JP56197342A patent/JPS5897965A/en active Granted
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS55124361A (en) * | 1979-03-19 | 1980-09-25 | Nippon Telegr & Teleph Corp <Ntt> | Redundancy suppression coding system |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5897965A (en) | 1983-06-10 |
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