CH629348A5 - Method for reproducing an image subdivided into elements by scanning - Google Patents

Description

The present invention relates to a method for estimating tes.

Reproduction of an image divided by scanning into picture elements in US Pat. Nos. 3,483,317 and 3,643,019, the degree of blackening for each picture element being the compression of graphic data by means of run length coding — using a number from “0” for white to “ N »for black determination with binary numbers corresponding to the generation of telt. 60 data blocks are described, while characteristic data in a facsimile transmission system consists of black data used to switch between «black» and «white» zen characters on a white background. In none of these patents is generally used on a cathode ray reproducing apparatus, however the principle is used in conjunction with a grayscale display tube or light emitting diodes, or to a dot printer, such as for achieving fine reproduction, and an alignment method which uses an ink jet printer or a wire printer Greyscale information. The images are mostly roughly scanned and coarse and the scanned neighboring information is used for printing, in order to enable faster transmission to the reproduction points, taking into account the associated neighbor unit. To set the roughly scanned information precisely.

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The scanning area reflects the publication-controlled pressure points belonging to the prior art. In addition, no method for compressing data is to be extracted.

a high-quality fine reproduction of an attitude but of all gray values is a procedure

signal originating from coarse sampling. Also presented for data compression.

there is little of the compression of graphic data under s. The roughly scanned characters are what

Inclusion of the gray value representation the speech, which are to be reproduced to a fine, converted into binary data and

Reproductions with little loss of resolution lead to a compression processor. This can condense. the data, the character information based on the

The purpose of the present invention is to identify a gray scale. The information is stored in a process for the fine reproduction of graphic material 10 and then, if necessary, presented by means of a transfer after rough scanning. In this case, the type of the diversion lines is to be fed to a decompression processor, and the processing of the scanned data should help to meet high demands. After decoding the digital information, it will avoid any changes to the data transmission. This allows fine reproduction matrix to be supplied, and thanks to the higher transmission speed on the one hand and gray value information, each coarsely scanned picture element results in less effort, that is, lower costs. Thanks to the fact that it is expanded that there is a reproduction matrix from the acquisition of gray values is still high quality of the fills. The concept of coarse scanning / fine printing can be guaranteed by reproduction. various processes that are used to improve the

As a result, the method according to the invention is suitable for printing the individual points in a suitable manner,

records that the resulting scan information is applied to one.

Reproduction device with a dot matrix of the format 20 According to the basic idea, the coarse scan delivers

Ax B = N for the reproduction of the scanned picture elements in relation to a character, a sample value from white over gray to completely is conducted, and that for each picture element to be reproduced black for each scanned picture element. This controls the number of fine reproduction points corresponding to its degree of blackening. In the present invention the matrix is actuated. but also the samples of surrounding picture elements

Exemplary embodiments of the invention are looked through in the attached 25 in order to shift the points of the fine impression against the drawings and are subsequently shifted closer to reproducing characters and do not inscribe them. They show: according to the gray value in any distribution

Fig. 1 in a block diagram a coarse scanner and a print. The fine print character reproduction as in

1 is very similar to that in FIG. 3

method, 30 conventional methods shown, the fine scanning

Fig. 2 the reproduction works according to conventional methods and fine printing. The reproduction system of the preferred embodiment with coarse scanning and coarse printing advantageously uses the low

3 shows a conventional reproduction method with more precise requirements for the data transmission of the rough samples.

scanning and fine impression, stung and at the same time improves the reproduction quality

FIG. 4A shows the steps of a method 35 according to the invention of coarse printing, as shown in FIG. 2. That with gray value with coarse scanning and fine print, to be carried out in an embedded image element 68 as shown in FIG. 8, in the direction according to FIG. 1, preferred exemplary embodiment for the 4 × 4 pressure dot matrix FIG. 4B, method steps according to the invention for the position of the fine printer . With the dot displacement control according to the invention of the printing or alignment method to be reproduced by the printer, which is shown in FIG. 9, points are obtained 40, better print quality than with uniform distribution of FIGS. 5A and 5B in block diagrams, different versions of the printing dots. If one proceeds from the square picture element examples for the compression process of the preferred exemplary embodiment shown in FIG. 1, the position of FIGS. 6A and 6B for a picture element intended for reproduction becomes explanatory representations for compressing the fine impression points for the gray value representation according to FIG. 10 sions process of the processor shown in Fig. 5A and 5B, 45 based on the scanning information of the eight surrounding scanning Fig. 7 changed in a block diagram the elements mentioned in FIG. 1. The picture element under consideration, designated in FIG. 10 with decompression processor, Z, and its pressure point information is correspondingly shown in FIG. 8 changed the transition from the individual scanning picture element according to the gray value through all eight surrounding scanning elements - a coarse scanning to a fine impression matrix with uniform A to H. The alignment process results in sig distributed pressure points, that each pressure point after a weighting, shown in

Fig. 9 the difference between a uniformly Fig. 11, is set. One of these eight patterns is selected

divided matrix print and the aligned according to the invention around the gray value by fine printing a corresponding one

Matrix print to reproduce the number of selected pressure points that the time

10 shows in a block diagram a device for inventing in this scanning element.

The present invention uses the alignment method.

7, serve to change the print quality of roughly scanned characters.

11 shows the various pressure point alignment patterns of the better ones. A larger scanning opening can be used in the present invention as a preferred exemplary embodiment without sacrificing the subtleties of the print resolution.

for the pattern selector of Fig. 10, the alignment process gains part of the information

12 shows a logic circuit for actuating a print-60, which is used by the scanning with lower resolution.

point as part of the pressure point selector of Fig. 10 and loren goes. The advantages of coarse scanning, namely lower ones

13 shows a possible point distribution in the print matrix. Requirements for data transmission are maintained.

for use with the pattern selector shown in FIG. 11. hold while the advantage of a fine printer, namely the

Character that is perceived according to the present invention in high resolution. In the preferred training

other image elements can be sampled, the sample values in the 65 exemplary embodiment lie between 0 and 16 for

Reproduction by using a gray scale, white, gray and completely black tint in the area of a color through which the printing of small dots 4 x 4 m atrix.

is controlled. The total area of the reproduction device of the described

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for example is a dot printer. The scanning opening of the scanner is larger than the area of a pressure point. This leads to a reduction in the scanning resolution. However, the print resolution remains high thanks to the inventive pressure point alignment process. In the exemplary embodiment, 16 pressure points are provided for each scanning element. A dot printer matrix of 4x4 dots can thus be controlled by a coarse scanner with a gray scale of 16. In the exemplary embodiment, the opening of the scanner results in 71 picture elements per centimeter and the pressure point size 284 picture elements per centimeter. The 16 gray values of the roughly scanned data bridge the density requirements of the picture elements between two otherwise incompatible systems, namely between the coarse scanning of 71 picture elements per centimeter and a fine reproduction with 284 picture elements per centimeter. Background information is white in the exemplary embodiment, while the character information is black with a gray scale which results from the activation of pressure points. Thanks to the pressure point alignment method according to the invention, better character reproduction is obtained. A threshold value matrix is selected that enables a clear alignment with the darkest surrounding patterns in order to obtain a high-quality reproduction. The method of coarse scanning to achieve fine reproduction by aligning the gray values of each picture element is explained in more detail below.

Fig. 1 shows how a character is roughly scanned to produce white or background information and gray or character information in each scanned picture element. In the exemplary embodiment, the gray scale comprises 16 possible gray values. In the first line of the coarse scan are covered by the character 5 / is of the picture element 20. In the second picture element 22 of the first line, the character covers the entire element area and is therefore completely black with a gray value 16. The third picture element 24 has a gray value of 12 of the possible 16 values and the fourth and fifth picture elements 26 and 28 of the coarse scanning have only Background information and are therefore identified as white, which can be designated with the gray value 0.

The roughly sampled information from the coarse scanner 18 is passed to a compression processor 30, where the pixel is identified as background or character information. The information is encoded in run length and stored accordingly. The character or edge information is identified and coded according to gray value, the exemplary embodiment knowing gray values 1 to 16. Each roughly scanned picture element is encoded and stored separately. The scanned finished information is passed to a transmission controller 32 to e.g. B. to be placed on the transmission line 34.

The binary data is then received by a receive controller 36 and passed to a decompression processor 38. The decompression processor 38 decodes the received binary data to separate the encoded run length information from the character or edge information and to decode the character or edge information according to the gray scale. The background and the character information, separated from one another by the gray value, control a fine reproduction system 40 according to the pressure point alignment method. The reproduction points for the gray value are shifted in the direction of the adjacent coarse scanning element with the largest number of points. The coarse sampling together with the processing of the data according to the compression method and the character decoding according to gray values allow the binary coded character to be transmitted at high speed. The precise precision reproduction device with the decompression processor and the alignment process allow high-quality reproduction of the

Character.

The advantages of coarse scanning and fine printing together with the alignment method mentioned are explained with reference to FIGS. 2 and 3, which represent known arrangements. An arrangement with a coarse scanner 42 and a coarse printer 44, both of a conventional type, is shown in FIG. 2. A coarse picture element 46 and a coarse pressure point 48 represent the area covered by a scanning position and a printing position. Coarse scanning has the advantage that a small amount of data is generated in one scanning operation and can be transmitted relatively quickly and easily. The conventional method generally consists in printing a black element or a drawing element if the drawing covers more than 50% of the area of the scanned picture element 15. As shown, the resulting character in the coarse printer 44 is only a raw representation of the character originally scanned. The stepped part of the sign proves to be disturbing for an observer. The process shown in FIG. 3 20 with fine scanning and fine printing is therefore used to improve the quality of the print and the resolution.

A picture element of the fine scan of a fine scanner 50, as shown in FIG. 3, is substantially smaller than the element shown in FIG. 2. With the same method as in FIGS. 2, 25, in which more than 50% of the character within a picture element results in a full printing dot, the character shown in the fine scanner 50 of FIG. 3 generates the character shown in a fine printer 52. The step shape of fine scanning and printing is hardly noticeable, since the eye of the viewer tends to see the rough edges balanced. However, this preferred character requires the compromise that fine-scan requires the transmission of a greater amount of digital information, even if known compression methods are used. The method of 35 fine scanning and the fine impression of conventional kind delivers a pleasing character reproduction at the expense of an expensive data transmission.

In order to be able to lower the demand for high resolution without sacrificing print quality, the advantages of the 40 roughly scanned character of FIG. 2 are combined with the advantages of the fine impression as shown in FIG. 3. The coarse scan produces less digital information to transmit, while the fine print gives an acceptable character without the non-accidental step shape of FIG. 2. This obvious incompatibility between coarse scanning and fine printing is solved by the inventive method shown in the flowchart in FIG. 4A. Generally speaking, the character is roughly scanned and the roughly scanned image elements are identified according to their gray value. In an exemplary embodiment shown in FIG. 5A, only white information is encoded in the known barrel length technique. Each picture element containing part of the character is encoded according to the percentage of the picture element covered by the character part.

In a second exemplary embodiment shown in FIG. 5B, white and completely black values are encoded according to the run length and only the character edges or partially black values are encoded according to the gray scale. In these exemplary embodiments, the fine print comprises 16 pressure points for each of the 60 roughly scanned image elements. All white is represented by the complete absence of pressure points. For each roughly scanned picture element that contains at least part of the character, a gray value between 0 and 15 is thus binary coded. The entire character display is saved in the background and gray values for transmission. The received coded information is decoded and decompressed according to the requirements of the fine print, i. that is, the "white" information is decoded after the run length coding,

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while the black picture elements are decoded according to the gray value or the whole black binary coding. The pressure point matrix of the fine impression is actuated in accordance with the information decoded from the gray scale. In order to better distribute the printing dots, the roughly scanned background and drawing information of the surroundings is used in an alignment process for weighting the printing dots and for shifting them towards the picture element which includes part of the drawing.

The fine reproduction shown in FIG. 1 results from this method. The fine reproduction shown in FIG. 1 can advantageously be compared with the reproduction that results from the fine scanning and the fine impression and is shown in FIG. 3.

In the flowchart in Fig. 4A, the process begins with the coarse scanning of a picture element. Next, it is determined whether this picture element is part of the background or the character to be reproduced. If the picture element is recognized as a character part to be identified by its gray value, the next step consists in determining the gray value in accordance with the percentage of the picture element which is covered by the sign. The identification of the picture element, namely its gray value, is binary coded and saved if necessary.

If the identified picture element is not to be coded according to the gray value, e.g. B. completely black or completely white, this data is compressed in a suitable manner, as shown in the method step after the step of identification and circumscribed with data compression. The next process consists in the appropriate coding of the compressed data and, if necessary, in their subsequent storage. The scanning process ends when the last picture element is roughly scanned and the binary information is ready for transmission to the playback device as shown in FIG. 1. The information is passed to the receive controller and to the decompression processor, where it is decoded and decompressed for reproduction in accordance with the process proceeding in Figure 4A.

The transmitted information is received in the next process step and sent to a memory. It is then decoded to differentiate between background information and character information. Together with the run length coding and the gray value data for a character, these form the byte from several bits, which represents a specific information group. This next step in the flowchart of FIG. 4A is to identify the byte as the background picture element or character picture element.

If the byte is a run length encoded picture element, the process continues with decompression of the run length encoding, which in turn determines the number of picture elements that are in a sequence. The picture elements are actually reproduced by triggering the printing process. The very black and very white picture elements are reproduced by using the fine reproducer as a coarse reproducer, i. H. In the present exemplary embodiment, a white picture element blocks the 4x4 print matrix in the fine reproducer and a black picture element actuates all print points of this matrix.

If the decoded byte identifies a character print element with gray values, the method for decoding the gray value information branches from the remaining bits of the byte.

The dot printing is controlled in accordance with the gray value information obtained. Furthermore, the points are then shifted according to an alignment method according to a preferred embodiment. The fine impression is thanks to the targeted shifting of the pressure points in

Improved the direction of the surrounding picture elements, which contain parts of characters. The steps for this printing process are shown in Fig. 4B.

4B shows the procedure in a point alignment method. The pressure points determined after the process steps shown in Fig. 4A are effectively aligned with the character. As is known, after the data storage in FIG. 4A, the information is decoded and the compressed data decompressed in order to separate the gray values. The gray values are decoded according to the method of FIG. 4A. To carry out the alignment method, the sample values of picture elements surrounding the picture element to be reproduced are called up in a further step. The next step is to sum the samples of the upper and lower horizontal, the right and left vertical and the corner positions for groups of three surrounding picture elements each and then comparing these sums to find the highest sum. The next step is to choose a matrix pattern that aligns the pressure of the dots according to preselected positions. This alignment determines the pattern that comes closest to the pressure distribution necessary to achieve the highest sum. The pressure points are set as before in accordance with the next process step and the image element is finely printed in the last steps discussed in FIG.

The information for a roughly scanned image element can of course also be passed directly to a fine reproduction device without taking advantage of the advantages of data compression. The gray values and the white picture elements can e.g. B. can feed this coding without coding. The white picture elements can switch off the print matrix and the gray values control the number of dots to be printed. To do this, the image element must be roughly scanned, identified at white or gray levels including black, the pressure points set according to the gray value and the printing carried out according to the set pressure points and the "white" image element information. Pressure points can be adjusted according to the method shown in FIG. 4B so that they are aligned accordingly. Of course, the data compression and the associated advantage in long-distance transmission, i. H. a possible fine reproduction with less data transmission than previously known, not used.

The object of the present invention is to reduce the requirements regarding the fineness of the scanning so that the number of bits to be transmitted can be reduced, while the resolution of the print should correspond as closely as possible to the original character. A lower resolution during the scanning means that a smaller number of picture elements is required, so that a light source with a lower output and a larger aperture is sufficient. The area for storing the character need not be so large with a lower resolution of the scanning. The advantages of coarse scanning and fine printing together with the improved method of identifying the position of the fine print pixel will be more closely related to FIGS. 5 to 13.

In the method of data compression for the scanning of black and white documents, an exemplary embodiment shown uses run length coding for the white background information and gray values for the black characters in the document. A byte thus contains information that the background and the size of the run length code, i. H. indicates the number of background picture elements combined in the code. A byte that contains character information also has bits that represent the gray value of the picture element. The data compression method of this embodiment

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can best be described with reference to Figures 5A, 6A and 6B. A letter “A” is shown in FIG. 6A, each square representing a roughly scanned image element 54. The fine impression of the exemplary embodiment is made by a printer which can print 16 dots in a square 4x4 dot matrix for each roughly scanned picture element 54. The bits required to actuate the 16 pressure points are obtained from the decompression processor 38 of FIG. 1. A more detailed block diagram of this decompression processor 38 can be found in FIG. 5A. A block diagram of an even more effective compression method with a second type of decompression processor 38 is shown in Figure 5B.

When a character is scanned, as shown in FIG. 5A, the analog signal is converted into 16 gray values in an analog / digital converter 56, 1 being the lowest gray value and 16 representing the value for completely black. The lead bit of each byte indicates whether the byte contains background information and thus represents the run length with the next bits or whether it is a character picture element and thus contains the remaining bits in the byte gray values. For the present exemplary embodiment, a “0” in the lead bit represents the background information and the next four bits of the byte are therefore run length information. A “1” in the preprocessing bit means that the byte represents character information and the next four bits contain the gray values.

FIG. 5A shows that the compression processor 30 comprises the analog / digital converter 56, the comparison detector 58 for background / characters, a transition detector 60, a run length counter 61, a run length encoder 62, a gray value encoder 64 and a memory 66. The analog / digital converter 56 receives the analog signal from the scanner 18 and converts it to an either completely white d. H. Background signal or in a gray value or character information signal. The background signal is applied to the run length counter 61 to count the number of white picture elements until character information is sensed. The comparison detector 58 and the transition detector 60 sense the deviation from completely white picture elements. At this time, the number of background picture elements is known and the background byte OXXXX can be encoded in the run length encoder 62. The transition detector 60 can be a flip-flop circuit that senses the transition from white to gray or vice versa. The lead bit "0" indicates that this byte contains background information, while the remaining bits define the binary number of background or white picture elements in a row. The character information is converted in the analog-to-digital converter 56 into a gray scale value of the scale 1 to 16 and sent to the gray scale encoder 64. The gray-scale encoder 64 generates a byte 1XXXX, the preprocessing bit “1” indicating that this byte contains character information. The remaining bits represent the digital gray value in binary coding. The gray value encoder 64 is actuated by the comparison detector 58 by sensing a character.

The binary coded background and character information is generally stored serially in the memory 66 so that it can be transferred more easily when the transfer controller 32 is actuated. The transmission controller 32 then retrieves the information from the memory 66. An example of the coding and compression method of FIG. 5A is explained with reference to FIG. 6A, where the letter A is shown in black on a white background. Each square represents a roughly scanned picture element 54. There are 12 picture elements in each scanning line. 15 scanning lines cover one character line. The table in Figure 6B shows the identification of rows F and K for the 12 picture elements. The “0” in the line denotes a picture element that is sensed in white and the “1” denotes a picture element that is sensed in black, the number in brackets indicating the gray value on the scale 1 to 16.

6

In FIG. 6A the picture elements 1 to 4 and 10 to 12 represent background or white picture elements in line F. The picture elements 5 to 9 represent the picture information of different gray values. For the original background run length s byte the binary information bit is represented as 00011, the first “0” bit designating the byte as the background byte and the binary-coded 3 indicating that three further picture elements also represent the background. The next byte could be encoded at 11011 and represent the fifth information. The lead bit “1” indicates that the byte contains character information and the binary-coded eleven of the next four bits indicate the gray value of 12 as shown in FIG. 6B. For coding, the gray values 1 to 16 are shown as binary coding 0 to 15 or 0000 to 1111. The picture elements 6 and 7 15 of the line F are completely black, their gray value is therefore 16, and thus they are identified by the coding 11111. The picture element 8 of the line F can be identified by the gray value 12 and is coded by the byte 11011. The picture element 9 is characterized by a character-20 position with the gray value 1, since only a small corner is covered by the character and this picture element is therefore represented in binary form in the byte as 10000. The other picture elements 10 to 12 contain white or background information and therefore have a run length code of 00010, which means that the 25 picture elements represent background and the first picture element is followed by two further white picture elements. For line K in FIG. 6A, the scanning fields 1, 2, 6, 7, 12 and 12 contain only background information according to the table in FIG. 6B and therefore the lead bit is coded with “0” and this “0” 30 is followed by Run length coding. The scanning fields 4 and 9 have gray values of 16 for completely black and the scanning fields 3, 5, 8 and 10 have average gray values between 0 and 16. With the average gray values listed in the table in FIG. 6B, a data block is used for the line K. the following nine 35 bytes: 00001,10111,11111,10111,00001,10111, 11111,11001,00001. This message block, together with other line message blocks, forms the binary information stored in the memory 66 of FIG. 5A for later transmission from the transmission controller 32 of FIG. 1 to the reception controller 36. When this compressed data is received, it is reconstructed the decompression processor 38 signs a fine print reproduction with a resolution that is 4x4 times finer than the scan field with a coarse print, there are 12x15 picture elements in Fig. 6A. These are expanded to 48x60 print elements or fine print dots.

5A generates well compressed data information, but too much superfluous gray value information is transmitted, for example, for “completely so black”. In line M, the run length coding for "all black" would drastically reduce the number of data transferred. The only gray values required for best reproduction are the values at the edge of the drawing. FIG. 5B therefore shows a second exemplary embodiment for 55 a compression processor 30 from FIG. 1.

The compression processor 30 shown in FIG. 5B comprises the analog / digital converter 56, a three-line buffer 57, the comparison detector 58, an adder 59, the transition detector 60, a run length counter 61 A for white, a run 60 length counter 61 B for all black, the run length encoder 62, a comparator 63, the gray value encoder 64, a gradient detector 65 and the memory 66. As in the embodiment of FIG. 5A, the sampled picture element signals are sent to the analog / digital converter 56, where the 65 are analog Signals from the scanner are digitized, whereby 0 represents white, 16 completely black and the values 1 to 15 gray values. The output signals from the analog / digital converter 56 are passed to the comparison detector 58, where the

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Characteristic of the picture element is determined. Since an otherwise completely white or completely black picture element can accidentally contain a black or white spot,

the encoded picture element Y is first compared with the surrounding picture elements. 5

The digital information of the surrounding picture elements A to H is placed in the three-line buffer 57 together with the picture element Y coded according to the pattern shown. The information from the three-line buffer 57 is fed into the adder 59, where six sums are formed, which appear at the 10 outputs from the adder 59 to the sum comparator 63, by means of the sum comparator 63 receives the largest sum and the smallest sum from the sum outputs of Adder 59. These signals are provided to gradient detector 65, where the smallest is subtracted from the largest sum 15. If the output from gradient detector 65 is low, i. H. is below a setting that says

that the surrounding picture elements have essentially the same value, be it black or white, then the comparison detector 58 is actuated to input the picture element into the corresponding run length counter. If the output from the gradient detector 65 is high and thus indicates a strong contrast, the gray value encoder 64 is actuated and the gray values are encoded accordingly. The transition detector 60 senses a change from white to black or vice versa and actuates the run length encoder 62. This appropriately encodes the information for storage in the memory 66, together with the directly stored gray values from the gray value encoder 64. The output signals from the memory 66 are given to the transmission controller 32 of FIG. 1 as needed.

For the exemplary embodiment shown in FIG. 5B, a run length byte 00XXXX with the leading bits “00” can mean a coding of white picture elements, the binary numbers XXXX again indicating the number of subsequent white picture elements. A run length byte 10XXXX can be a run length coding of completely black picture elements, whereby the binary numbers XXXX again denote the number of subsequent black picture elements. The gray values can then be coded as 11 XXXX, the leading bits 40 “11” denoting a gray value and the remaining bits of the byte being the binary coding of the gray values. Line F of FIG. 6A would thus be coded with 000011 for the first four picture elements, with 111011 for the fifth scanned picture element, with 100001 for the scanned picture elements 6 and 7, which are completely black, with 111011 for the gray value of the picture element 8 , with 110000 for the gray value of the picture element 9 and with the run length coding 000010 for the very white picture elements 10, 11 and 12. The number of coded bits does not differ significantly from the exemplary embodiment shown in FIG. 5A, but is considerably smaller if line M is encoded. By means of the exemplary embodiment shown in FIG. 5A, all picture elements would be encoded individually, since no white run lengths occur. By means of the exemplary embodiment in FIG. 5B, however, the picture elements 3 to 10 would be coded according to the run length as 100111 and not individually.

In a device according to the present invention, with the analog output signals of the scanner, which are divided according to a finer gray scale, the image information for feeding a device with high resolution is expanded. A roughly toned image element 68 in FIG. 8 supplies a “white” output signal 0 and 16 gray values. This information is expanded by pressing the 16 points on a print matrix. In FIG. 8, a fine print matrix 70 comprises the pressure points 72, which are shown in any value position. All points with the gray value or below are activated in each case. Pressure points 1 to 6 are thus activated for gray value 6 on a scale ranging from 1 to 16. The resulting fine printing block 70 is shown in FIG. 9 under the designation of an arrangement with an even pressure point distribution. A better distribution of the points after an alignment process is described later. The method steps of FIG. 4B and the receiving steps of FIG. 4A are described in the block diagram of FIG. 7 and show the decompression processor 38 of FIG. 1.

The data signals received by the reception controller 36 are passed to a memory 74 in the decompression processor 38 as shown in FIG. 7. The stored information is decoded into background and character information in a decoder 76. The run length signal is sent to a run length decoder 78 and the gray value signal to a gray value decoder 80. The gray value decoder sends a pressure point set signal to a printer 82, the fine reproduction system 40 of FIG directed, which controls the scanning and spatial distribution of the points in the Druk-ker 82. The run length and grayscale signals determine the location of the print, while the print dot set signals determine which dots are actuated to print a portion of the character in the printer 82.

The run length signals from decoder 76 are labeled 0XXXX and 00XXXX, 01 XXXX to indicate the output signals from the two compression processors in Figures 5A and 5B. In the same way, the gray value signals 1XXXX and 11 XXXX are signals from both exemplary embodiments of the decoder 76. The solid signal lines indicate the signal direction for the exemplary embodiment of FIG. 5A, while the dotted lines for the completely black signals are added for the exemplary embodiment of FIG. 5B.

Printer 82 in the present embodiment produces four print dots in each column of scan elements and four rows of print dots in each scan line. A scanning printer, the deflection of which is similar to that of a CRT, would take four scans to provide the information for one row of picture elements. The individual dots of each scan line can be according to the gray information received according to the in the Figs. 8 and 9 shown uniform distribution grid can be switched on and off. In the case of picture elements scanned in white, of course, no fine print points in the designated 4x4 matrix are actuated. In a dot matrix for character or line printing, all the dots to be printed and not to be printed are set in their position either in accordance with a preliminary scan or in accordance with data transmitted to the printer 82 in parallel from a buffer (not shown). Details need not be described here.

9 shows the influence of different settings of the print matrix on the fine print. If, for example, one uses the even distribution of the printing dots, the printing matrix 70, which is based on a character gray value of 6, has the printing dots distributed as desired, as shown. This distribution is carried out as shown in Fig. 8. However, if an alignment method is used according to which the black dots can be distributed according to a scheme by which the pressure dots are shifted towards the drawing area, then the pressure dots are set as shown in the print matrix 86 of FIG. 9. The differences in the resulting character printing are clear. The use of the alignment process leads to a much better reproduction of the original sign.

For a scanning element to be printed on the edge of a character, it would be advantageous to activate printing dots in the area which corresponds to the black area within the character. 8, a number of points are placed in the white backgrounds.

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basic areas set outside the sign. This is operated via the gray value. The general method for printing dots that protrude normal character boundaries in the present exemplary embodiment is based on

produce a blurred print image, since the characters normally have sharp boundaries due to the gray values of the same rank. Information from neighboring and operated by higher ranking information. All 16 beard image elements can be used to shift the pressure points. 5 pressure points are thus triggered by the gray value 16, to the dark side of the surrounding roughly scanned eggs. The pressure point arrangements shown in FIG.

lead. The proposed pressure point alignment from data blocks stored in a read-only memory can be regarded as nonlinear interpolation. A ken exist. The patterns are permanent or semi-permanent linear interpolation is largely set in the curve fitting in the read-only memory and signals are used accordingly and for statistical data analysis. 10 according to the stored pressure point patterns when

To use the pressure point alignment method, the read-only memory must be activated by an M signal from the comparator 96 for the width of the character line in relation to the scanning fields.

an opening can be made. So that it can be shown that each sensor senses the M signals from the unit or the gray value of the environment, comparator 96 will select the pattern corresponding to the orientation according to the representation in FIG. 10, either vertically following the image element to be examined eight image elements surrounding one side, horizonZ mentZ were examined in order to accordingly shift the points to be printed in the valley upwards or downwards or to one of the four corners of the scanning area. The adder 94 in Fig. 10 likes to combine the digital. The number of dots actually printed is determined by scanning information of each picture element in the three-line gray value of the processed picture element. The buffers 88 according to its output signals. The comparator gray values of different groups of three picture elements 20 96 each select the highest pattern sum and by means of this a matrix is added to a sum. This results in eight sum patterns of the pattern selector 98 shown in FIG. 11. The pattern corresponding to the eight possibilities of point alignment. Selector 98 actuates the pressure point selector 92, accordingly The eight sums correspond to eight patterns which are symmetrical to a set of AND gates 102 and OR gates 104. The pressure point selector 92 actuates the pressure points P1 to divided on both sides of four intersecting lines of the picture element , namely the vertical, the horizontal and two cutting lines in the 25 P16 according to the selected pattern and the gray value angle of 45 °. For any pattern signals. A representative logic circuit for the actuation sum is an associated threshold value matrix, which is shown in FIG. 12 when the pressure point PI is set. The individual print determines the location of the dots. A threshold value measurement pressure points PI to P16 can be arranged according to FIG. 13, trix, which is the largest value of the sample sum among the eight. According to the illustration in FIG.

corresponds to possible cases, the printing point PI of the print scanning picture element is selected for printing the dots in the 30 shear switching elements 106 to 114. The dots in each matrix are actuated in such a way as to matrix of FIG. 13, which distributes a picture element in such a way that it speaks strongly in the direction of the associated pattern. The pressure point PI is the top left point and is directed. The use of the alignment method can therefore give the gray-scale dots in the print quality shown in FIG. 11 that the original character excellently prints patterns in a similar position. If e.g. B. reproduces a signal. The implementation of the alignment process allows 35 ml to be received by the comparator 96, the AND gate will be easily realized in practice and requires various 106 to be actuated if the gray value signal (GW) from the binary / digital logic components and some memory space for the thresholds valley decoder 90 is equal to or greater than four. The initial value matrices. 10 shows a block diagram for the execution signal of the AND gate 106 switches the OR gate 114 and of the alignment method. this in turn the signal PI for actuating the pressure point PI.

For the alignment method, the gray value decoder comprises in the same way the other signals M2 to M8 rer 80 of FIG. 7, as shown in FIG. 10, actuate a three-line corresponding UN D element depending on the gray values (GW).

Buffer 88 in order to hold the examined picture element Z and the surrounding AND element 110, for example, only by the graying picture elements A to H. A binary / digital value 16 actuates when either the signal M4 or M8 decodes via encoder 90, the binary character byte 1 XXXX or the OR gate 109 controls a branch of the AND gate 110. 11XXXX in a gray value from 1 to 16 for the selection of the “The patterns 116 and 118 shown in FIG. 11 show that with pressure points by means of a pressure point selector 92. only a gray value 16 den of the actuated signal M4 or M8

The gray scale decoder 80 also includes an adder that will actuate the top left pressure point PI. The various items 94 for summing certain gray value information from other pressure points can be operated in a similar manner logically to the surrounding picture elements in accordance with the selected ones by means of a corresponding pattern selection and the logical switching patterns, a comparator 96 for selecting the highest 50 elements which are shown in 10 and 12 show sample sum of certain picture elements and a sample selection.

1er 98 for controlling the pressure point selector 92 accordingly The alignment method, i. H. the choice of a fixed smolder - the highest determined sample sum. The eight patterns of the lenwertmatrix, which are clearly aligned with the darkest surrounding preferred exemplary embodiments, generated by the pattern selection pattern, generated with a coarse scan and 1s 98, are shown in FIG. 11 and will be described later. 55 a reproduction of a fine print device, the quality of the buffer 88 and the adder. 94 together with that of fine scanning and reproduction by means of a numerical pattern determined by the pressure points, which is comparable to the printed fine print device. A high-quality copy of the are that the printing dots with low ranks in Rieh original text can be placed in front of the selected areas with a large scanning opening from tung. If, for example, 71 picture elements per cm and a fine impression - that is from the comparator 96 - the gray values A + B + C from the addieo device of e.g. B. 284 picture elements per cm. The larger rer 94 can be determined as the highest sum, then this triggers the scanning opening and leads to a small number of picture element signals M1. The pressure dots that result for the picture element Z th from the scanning and therefore lower the necessary ones are aligned with the upper edge of the print matrix for this exposure power and the required storage space for the picture elements. Fig. 11 shows the position of the print transmission and the reception processing. In the same way, dots in the matrix pattern 100, the pressure dots with the e? the transmission time for the smaller number of bits of the informa-low print number is reduced closer to the upper vertical position, since the number of picture elements is significantly brought up. The lower rank of the print loan decreases. Nevertheless, the reproduction quality is indicated by the dot that this pressure point is not significantly impaired by a low-coarse key.

G

12 sheets of drawings

Claims (8)

629348 2 PATENT CLAIMS can be encoded and compressed before transmission, 1. A method for reproducing an image divided by scanning in picture elements to facilitate transmission to the reproducing apparatus, the degree of blackening and speeding up. A suitable decompression procedure for each picture element by means of a number from “0” for white to ren provides the original information “N” for black again after receipt, characterized in that 5 mation. the resulting scanning information is reproduced in order to achieve a high-quality reproduction of the original image with a dot matrix of the format Ax B = N, one generally uses a fine scanning device which supplies the scanned picture elements and that and an equally fine reproduction device. For a high-quality image for each pixel to be reproduced, the characters are actuated with approximately 284 pixels corresponding to the number of dots of the matrix actuated per centimeter and scanned at the same pixel rate. reproduced. This gives you a very good 2. The method according to claim 1, characterized by the original characters. This high number of picture elements, that before the actuation of matrix points blackening on the scanning device, despite data compression, forces the picture element to be reproduced to save a lot of information bits, since many picture elements of bender picture elements are summed up in groups, that f 5 for the transmission into binary information converted comparison of the sums the highest of them and thus must become one. Direction indication on a line detected by the scanning. In order to determine the complexity of the devices for the scanning, and also to reduce it on the basis of the direction specification and storage of the data, a predetermined weighting pattern for the matrix points is generally used to denote the characters at a rough rate of, for example, 71 in order to favor the specified direction at which 20 picture elements per cm are scanned and reproduction is selected at the same rate and that finally the matrix is reproduced or printed. Thanks to this rough grid, points will be pressed according to their weight. less storage space and less data transfer 3. The method according to claim 2, characterized marked rate used. But when it comes to rendering, the print is that three of the surrounding picture elements are of low quality and many clearly visible, staircase-like groups are summarized that the degree of severity, which is unacceptable to a viewer, is the sum of eight of them Groups are determined. Sampling, binary coding, transmission and reproduction, the horizontal top and bottom, vertical right and left of scanning information are generally known. But the methods of character scanning, the ment, as well as those made known in the four corners around the image to be reproduced, and that finally by selection of the weighting and coding, transmission and reproduction, corresponding actuation of the matrix points enables the latter in rows just a rough representation of roughly sampled data. be transferred to the captured character. If better playback quality is required, only that remains 4. The method according to claim 1, characterized gekennzeich- fine reproduction of finely scanned characters, net that an inkjet printer is used as a reproduction device. In image processing, data compression is seen in which the generation of dots from ink largely uses interpolation. This is controlled together. 35 hang on the article «Redundancy Réduction - A Practi- 5. The method according to claim 1, characterized in cal method of data compression », by C.M. Kortman in net that at least Proceedings of the IEEE 55, March 1967, pages 253-263 of the resulting scanning information, and on the background information in order to simplify the article “Adaptive Data Compression”, by C.A. Andrews Data transmission is compressed by encoding and is decompressed again before the reproduction reproduced in Proceedings of the IEEE, March 1967, pages 267-277. 40 sen. For more effective coding of black and white gray 6. The method according to claim 5, characterized by characteristic data. P. Stucki in his article «Effi-net that a running transmission of graphics using polyomino filtering at length coding is used to encode the background information. the Receiver »in IEEE Transactions on Aerospace and Electro- 7. The method according to claim 5, characterized in system AES-6, November 1970, pages 811-814, a Ver-net that in addition to the background information "white" you 45 drive to reconstruct the original data with the opposite of the reproduction "black" likewise by means of a coding compression system if only every second sample is decompressed in a raster scan and before reproduction. power is transmitted while adjacent bit patterns with 8. The method according to claim 1, characterized gekennzeich- a so-called "polyomino filter" to be examined. net that the scanning information both before and after an In the article «Image Coding Via a Nearest Neighbor Data transmission is saved. 50 Image Model »by A.K. Jain, in the IEEE Transactions on Communications CO M-23, March 1975, pages 318-331, describes a model that uses a next neighbor image to code gray-scale images. So it can be said that the interpolation schemes in these articles use adjacent 55 sample elements to determine the value of a sample element.