JPH02239384A - Method and device for compressing digital signal group - Google Patents

Abstract

PURPOSE:To correspond to the change of an original digital signal group at high response, and to improve compressing efficiency by obtaining the changing degree of the value in the measured value direction of the original digital signal group, and determining the length of a compressed section corresponding to the changing degree. CONSTITUTION:A picture data input device 5 scans a picture 1 in an X direction to detect its density, and reads the original digital signal group. Next, a changing degree arithmetic means 12 operates the changing degree of the signal group, for the signal group including the high frequency component area, a compressed section length determining means 13 shortens the length of the compressed section where the changing degree is sharp, and extends the length of the compressed section of the part where the changing degree is gentle. Further the prescribed compressing processing is executed at every section by a signal compressing means 14, a single compressing signal is obtained, and the compressed digital signal group is prepared as a whole. Thus the change of the original digital signal group can be made to correspond at the high response, and the compressing efficiency can be improved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a digital signal Q that compresses a group of original digital signals whose values change with respect to one measurement direction into a compressed digital signal aT having a smaller number of signals. j! I! Concerning compression methods and reloading.

[Conventional technology]

In general, in order to improve efficiency when converting an arbitrary change m into an original digital signal {iig4Y whose value changes with respect to one measurement direction and further utilizing this original digital signal group, the change in value is Although the trend corresponds to the original digital signal JIT, the number of signals is compressed into a compressed digital signal group that is smaller than the number of signals in the original digital signal group.

As an example of compressing such a digital number G group,
For example, as shown in FIG. 9, the arbitrary image 1 is used as the reproduced image face 1a on M3, and pudding 1~? 1'.

To explain further, FIG. 9 shows a case where both images 1 and characters 2 shown on the leftmost part are edited and printed as recycled drawings 1a and recycled characters 2a on paper 3 as shown on the rightmost part. It shows. One character 2 is converted into a digital signal by a character data input device 4 such as a 1--board, and is input as character data to the host computer 6. The other image 1 is the image data input device "5" of Images-1
The image data is read as image data and inputted to the host 1 to the computer 6. The image data read from this image 1 is an original digital signal consisting of a set of daisicle signals obtained by measuring the depth of the image 1 for each unit image system along the scanning direction of the scanning line. If this original digital signal is used for printing 1.1 Image 1, it will be too
Often used as l1a, host computer 6 and printer 7
This places a heavy burden on control devices such as the CPU of the computer and makes them more efficient than necessary, resulting in an octavalent device.

Therefore, a compressed digital signal with a small number of signals that changes according to changes in the original digital signal has been created, and using this compressed digital signal, the host computer 6 performs editing processing for both igI1 and character 2. It is now possible to do this.

Is the mark J: created on this host computer 6? The data is sent to the printer 7, and the printer 7 prints the reproduced image {11a and the reproduced characters 2a on the paper 3 based on the received print data.

[Problem to be solved by the invention]

However, conventional methods for compressing original digital signals have the following problems.

In other words, an image data input device? ? Reading of the depth of the image 1 using the scanner 5 is carried out by repeatedly measuring the images 1 shown in FIG. 9 while scanning them in the x direction in the y direction.

FIG. 10 shows image data consisting of the degree of density of the image @1 along one scanning line obtained by scanning the image 1 in the X direction using the image data input device 5. There is. In this image data, the gradation value of D degrees measured for each pixel in the X direction of both 8A1 is used as a digital signal value, and these digital reliability values are displayed as a line graph. It is full of original digital signals that change f. When compressing this image data, the 10th
As shown in the figure, the entire scanning direction range in the X direction of image 1 is
/J direction with many equal width compression sections υ1
The original digital signal group divided for each compression section is
The signal is compressed into two compressed digital signals.

However, as in one image data shown in FIG. 10, the original digital signal group often includes a high frequency component region whose value changes rapidly and a low frequency component region whose value changes slowly. In order to compress high-frequency components, the responsiveness changes in response to changes in the high-frequency components.
It is necessary to know the measurement direction quality of the reduced section, that is, the quality in the X direction.

However, if the length of the compression section in the X direction is reduced,
J3 in the low frequency component region creates more compressed digital signals than necessary, and the overall result contains extraneous data and has poor compression efficiency, resulting in various subsequent problems in the computer 6 and printer 7. This places a large burden on the control processing.For this reason, in the conventional method described above, it is difficult to set the number of equal parts of the entire scanning range, that is, the length of the compression section in the measurement direction, to an appropriate value. I couldn't make a decision.

The present invention has been made in view of these points, and converts a group of original digital signals whose values change in one measurement direction into a group of compressed digital signals whose responsiveness changes in response to the change. It is an object of the present invention to provide a digital signal@group compression method and apparatus that can efficiently compress digital signals in a small number of compression sections.

[Means to solve the problem]

In order to achieve the above object, the digital signal CT of the present invention
The compression method is a digital signal group compression method in which an original digital signal group whose value changes with respect to one measurement direction is compressed using compression intervals divided into a plurality of compression intervals in the measurement direction. It is characterized by having unequal lengths in the measurement direction.

In addition, in order to achieve the 114-dimensional value, the digital signal group compression device of the present invention calculates the degree of change in the value of the original digital signal MY in the measured value direction of the original digital signal MY whose value changes with respect to one measured value direction. The apparatus includes a change degree combination means and a compression interval length determination means for determining the goodness of the measured value direction of the compression interval according to the change degree of the original digital signal group obtained by the change degree combination means. It is characterized by being formed by

[For production]

According to the present invention, by operating the device according to the present invention in accordance with the method of the present invention, it is possible to efficiently compress the original digital signal group and generate a compressed digital signal group.

That is, the change degree combination n means determines the degree of change in the original digital signal group (((the degree of change in the + direction), and the reduced interval length determining means determines the quality of the reduced interval j according to this degree of change). As a result, each compressed digital signal is created based on each compressed section with unequal lengths in the measuring direction, and a compressed digital signal with high compression efficiency that responds responsively to changes in the original signal signal q group is created. A compressed digital signal group 19 is generated.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 8.

In this embodiment, as the original digital signal group, as shown in FIGS. 1 and 2, image 1p data consisting of the gradations of both images 1 is used as in the conventional case.

FIG. 1 schematically shows a digital signal nY compression device 11 of the present invention.

Digital signal group compression device 1 1 i. of this embodiment. i,
Original digital signal whose value changes with respect to one measurement direction
A change degree calculation stage 12 calculates the degree of change in the X7J direction of image data consisting of gradation values of It has 1,000 compression section length determination stages 13 for determining the direction length, that is, the length in the X direction. Further, the signal compression stage 14 converts the original digital signal group within the compression interval determined by the compression interval length determination stage 13 into one compressed digital signal ft according to a predetermined method, and each of these means performs related operations. The CPU 15 to be stirred is on the right.

Next, the operation of this embodiment will be explained.

In this embodiment, as shown in FIG. The original digital signal group constituting the image data within the compression section is converted into one compressed digital signal.

To explain this motion with reference to the schematic flowchart 1 in FIG. 4, when the compression processing motion is started, first, as shown in step ST11, an A directional density detection scan is performed to read the image display data, that is, to read the original digital signal group. Next, as shown in step ST12, a compression interval is set by the change degree Kn means 12 and the compression interval length determination stage 13. That is, the degree of change calculation means 12 calculates the degree of change in the values of the original digital signal group, and the compression section length determining stage 13 determines the quality of the compression section according to the degree of change.

Next, in step ST13, a predetermined compression process is performed for each compression section by the signal compression stage 14 to obtain one compressed digital signal for each, and a compressed digital signal ε is created as a whole.

Although there are various methods for setting the compression interval in step ST12, the degree of change in value is large for the original digital signal containing a high frequency component region, such as the image data shown in FIG. It is better to shorten the length of the compression section of the part and increase the length of the fXm section of the part where the rate of change is gradual. can be obtained.

In addition, in order to concretely set the compression section 43 in step ST12, the starting point d3 and the end point of each compression section, which are not shown as black circles on the X-axis in FIG. 3, can be set smoothly. And it can be done properly.

It is preferable to perform a long distance selection of this interval point, for example, in accordance with the table 1 shown in FIG.

That is, in step ST21, a plurality of pixel positions, ie, X ordination of pixels, in locations where the degree of change in value is more severe than in the image data of FIG. 3 are selected as interval point candidates. next,
In step ST22, the plurality of interval point candidate sets selected as described above are narrowed down to a predetermined number of interval point candidates. Next, in step ST23, the ward point candidates narrowed down as described above are narrowed down to those separated by a predetermined double prime number or more. Next, in step ST24, a number of new section point candidates corresponding to the number reduced by the narrowing down in step ST23 of IYJ are replenished,
A predetermined number of interval values are determined, and a compression interval is determined.

The flowchart in FIG. 6 is an example in which the flowchart i in FIG. 5 is further modified.

To further explain this FIG. 6, step ST31
A plurality of interval point candidates are selected in . This selection is to select a location where the degree of change in image data is large, and as a selection method, it is preferable to select pixels that satisfy the following conditions (1) and (2), for example.

Now, let the gradation value of the pixel data shown in Figure 3 be a function O (X), let the gradation of the pixel at position i in the X direction be '(i), and D(i) = ' (i+ 1) ' (i), (1) D(i-t) − D(H, <0(2>
+max(ID(i-1, I. 10(H)
l) >C, where C is a constant (default value) where both t1 is added.

The condition in (1) and (2) is that the digital signal of the pixel part whose X coordinate is m changes between each pixel part before and after the unit pixel. , moreover, the condition is that the product of the absolute values of each change is greater than or equal to a predetermined number C, which exceeds the degree of intensity of the change.

Next, in step ST32, the step ST3
For each interval point candidate selected in step 1, the following formula wax
(10(B-1) l, ID l ) (i) The order is given in descending order of the performance nVi. In this case, if there are a plurality of section point candidates with the same calculated value and it is necessary to select one from among them, for example, the one with the smallest X coordinate value of the pixel is selected.

Next, in step ST33, a predetermined r! Select the upper interval points of l (for example, 30).

Next, in step ST34, it is determined whether or not the interval between the 30 selected section point candidates falls within a predetermined number of pixels.

If the section point candidate is located nearby, the determination is YES and the process proceeds to step ST35; if the candidate is not located nearby, the determination is NO.
If it is determined that the result is o, all the section point candidates selected in step ST33 are set as regular section points, and the section point selection operation is ended.

Next, in step ST35, one of the two section point candidates that have been determined as the nth nearest neighbor points is deleted, and the other is left as the section point candidate. In this case, assuming that the interval point candidates whose X coordinates are 1 and j are close to each other, comparing D(+-o ``m' and ``(j-1)'' (j), Keep the larger value and delete the other.

Next, in step ST36, it is determined whether the total number of ward point candidates selected so far is the predetermined number (30 in this embodiment) determined in step ST33, and Y
In the case of S, the section point selection operation is ended, and in the case of No, the process proceeds to step ST37.

In this step ST37, the predetermined number (30)
Step ST
In the same way as 32, select and add soil in order, and add it in step S.
Return to T36.

The operations in steps ST and ST3■ are repeated until the determination in step ST36 becomes YES, thereby completing the ward point selection operation.

By determining the predetermined number (30) of interval points as described above, the compressed interval between the J interval points shown in FIG. 3 is determined. This compression section is set such that the section length is short in the high frequency component region and the section length is long in the low frequency component region.

Thereafter, in step ST13 shown in FIG. 4, a compressed digital signal is obtained using each compression section, and as a rest, a group of compressed digital signals in one scanning direction is obtained.

This compression process IiI! ．． By repeating the IJJ process for all pixels in the y direction, image data for the image 1-Q1 is created.

The compressed digital signal group obtained in this way is sent to the host 1/computer 6, and is combined with the character data of character 2 sent to the small string/computer 6 through the character data input device 4. The printer 7 prints the reproduced image (!G
It is printed as l1a.

This is a picture of the unprinted residing statue 1a! No. 1, the image quality is almost the same as that of original image 1.

This is a compressed signal created by the signal compressing means 14 based on compression intervals with non-uniform interval lengths determined by the change degree calculating means 12 and the compression interval length determining means 13 of the digital signal group compression device 11. This is because the reproduced compressed digital signal, which is a group of digital signals connected so as to change smoothly in the X direction, changes almost in the same way as the original digital signal group consisting of image data. Also, compared to the original digital signal, the compressed digital signal group is compressed and greatly reduced in its information load, that is, as a data base, so that the boss i/computer 6 and printer 7 have no negative impact. II1t), thereby making it possible to perform high-speed data processing.

Next, each compressed digital signal 5Y J3 and each compressed digital signal obtained by compressing the same n group of original digital signals by the tree embodiment method and the conventional method are smoothed in the X direction. The reproduced compressed digital signal group connected in J; which changes to J; is compared with FIGS. 7 and 8. FIG. 7 shows the results obtained by the method of this example, and
The figure shows the results obtained using the conventional method. The image data to be compressed, shown by the solid line in both figures, consists of 256 pixels (one scale has two cumulative strokes), and represents the density gradation of image 1 as a digital signal value for each pixel in the entire scanning direction range. It is.

In the method of this embodiment, as shown in FIG. 7, the entire scanning range in the b direction is divided into a total of 49 compression sections (section points are indicated by black circles or white circles on the X axis) with different section lengths. The signal is divided uniformly and the compressed sections are used to create a compressed digital signal.

In the method of this embodiment, the entire scanning direction range is divided into compression sections having different section lengths, and the compression sections are used to generate a compressed digital signal. This compression section length needs to be short in the high frequency component region,
If the fluctuation of the gradation value is very large, the interval length may be ``0''. (When the interval length is ``0'', there is 1.) In this example, as shown in FIG. 7, nine interval points overlap (points indicated by white circles). Therefore, it is divided into a total of 49 compression sections. The broken lines in FIG. 7 indicate a group of reproduced compressed digital signals that connect the reproduced n-1 compressed digital signals obtained by reproducing each compressed digital signal. In FIG. 7, when the image data (actual a>) and the reproduced compressed digital signal (broken line) overlap, the image data, which is the original digital signal group, is shown with priority.

Also, J3 and LL in the conventional method are shown in Figure 8? jJ, sea urchin, divide the entire scanning direction range equally into 5I81 compressed sections (section points are indicated by black circles on the X axis) with uniform section distribution,
A compressed digital signal group is created.

The broken line in FIG. 8 connects the reproduced compressed digital signals obtained by reproducing these compressed digital signals (one compressed digital signal group).

Comparing these FIGS. 7 and 8, it is found that according to the method of this embodiment, the number of compression sections of the conventional force method is approximately 1
/2 number of compression intervals Iri. While the digital signal is compressed, the re-I-F compressed digital signal (n) that has been subjected to IRI is as good as the conventional example with a large number of compression sections, and has good responsiveness to changes in the values of the original digital signal group. It will be compatible. Therefore, according to this embodiment, the original digital signal group can be compressed extremely efficiently.

In the embodiment described in J3 and 11ii, the compression target is the original digital signal I! consisting of a clear and light combination of each stroke of the image 1! T
However, any digital signal group whose value changes in one measurement direction can be compressed.

In addition, how to determine the goodness of the measurement direction of the compression section,
Methods other than those in each of the above embodiments may be adopted.

Further, the method and apparatus of the present invention are not limited to the above-mentioned embodiments, but can be modified in various ways as necessary.

〔Effect of the invention〕

In this way, the digital noise group compression method of the present invention and H
Since a position is constituted and acts, a single, 1l1
It is possible to compress a group of original digital signals whose values change in the value direction into a group of compressed digital signals whose values change in response to the changes, and also to improve efficiency with a small number of compression sections. It can be compressed well and the subsequent signal processing can be performed simply and at high speed.

[Brief explanation of drawings]

1 to 7 show an embodiment of the digital signal group compression method and apparatus of the present invention. A diagram showing the case where it is used in a printer that performs processing and image reproduction. Flowcharts 1 and 7 respectively show the state of compression processing according to the method of the present invention. 8 is a diagram similar to FIG. 7 showing a conventional example for comparison with the present invention, and FIGS. 9 and 10 are conventional examples, respectively. FIG. 3 is a diagram similar to FIGS. 11... Digital signal group compression device, 12... Change degree calculating means, 13... Compression section length determining means, 14
... Shintan compression means, 15... cpu. Figure 1

Claims (1)

[Claims] 1) A digital signal group compression method in which an original digital signal group whose value changes with respect to one measurement direction is compressed using compression sections divided into a plurality of compression sections in the measurement direction, A digital signal group compression method characterized in that the lengths of the compression sections in the measurement direction are unequal. 2) change degree calculation means for calculating the change degree of the value in the measurement direction of the original digital signal group whose value changes with respect to one measurement direction; and A digital signal group compression apparatus comprising compression section length determining means for determining the length of the compression section in the measurement direction according to the degree of change.