JPS60196069A - Area discriminating method - Google Patents

Abstract

PURPOSE:To reduce the capacity of a desired memory and also to attain a high- speed discriminating action by binary coding the read data on a prescribed original area with two threshold values different from each other and giving a logic operation to the obtained binary coding data to discriminate whether the original area is equal to a binary area or a half-tone area. CONSTITUTION:An original 3 put on the contact glass 3 is exposed by a light source 1, and the reflected light of the original 3 is led to a CCD line sensor 6. Then the output of the sensor 6 is applied to an area discriminating part 7. The part 7 converts the output signal of the sensor 6 into the digital data by an A/D converter 8. This digital data is supplied to comparators 9 and 10, and the binary coding signals of both comparators are applied to an exclusive OR gate 11 to obtain an exclusive OR between both binary coded signals. The ''1'' level signals obtained during said processing are counted by a counter 12, and the count value of the counter 12 is applied to a comparator 13 to be compared with the reference value. Then a binary area or a half-tone area is decided according to the 0 or 1 level of the output signal of the comparator 13.

Description

[Detailed Description of the Invention] Technical Field> The present invention relates to an area discrimination method, and more specifically, the present invention relates to an area discrimination method, and more specifically, whether each part of a document is a halftone area such as a photograph, or a binary area such as a typed character. The present invention relates to an area discrimination method for determining whether

<Prior art> In image processing devices such as digital copying machines and facsimile machines that read a document and process the read data to obtain a copy image, transmission signal, etc., it is necessary to obtain a copy image, transmission signal, etc. that is as faithful to the original as possible. In order to achieve this purpose, it is necessary to determine whether the whole or part of the document is a halftone area like a photograph or a binary area like typeface, and It is known that it is necessary to process read data based on the determination result.

Based on the above empirical rules, area discrimination methods have been provided, one of which is @proverb *Sf
i*1. There is a method of forming a histogram and determining the type of area based on the histogram pattern, but this method not only requires a large amount of memory but also takes a long time to perform the determination process. I needed it.

In addition, Haku's method involves differentiating the original reading signal, and then
There is a method of determining the type of region by converting the differential curve into binary pulses using a predetermined threshold value and comparing the number of pulses with a preset reference value, but it is difficult to set the reference value.

Still another method is to binarize the original reading signal using a dither method, obtain the run length in this binarized image, and determine the type of area based on the frequency of black and white inversion, but the dither pattern Since the binarization is performed using , there is a problem that the minimum size of the discrimination area is restricted by the size of the dither pattern.

<Purpose> This invention has been made in view of the above problems, and aims to make it possible to easily and quickly determine the type of an area of any size using a small amount of memory. .

<Structure> In order to achieve the above object, the area discrimination method of the present invention binarizes read data in a predetermined area of a document using two different threshold values, and performs a logical operation on the obtained binarized data. By doing so, processing data is obtained in which the mutually different level portions of both binarized data are made to be at a different level from the remaining portion,
The number of "0" level or "1" level in this processed data is counted, and depending on the number of counts, it is determined whether the data is in a halftone area or a binary area.

<Example> Embodiments will be described in detail below with reference to the accompanying drawings showing embodiments.

Figure 1 shows the area of MXN for area discrimination, Figure 2 shows the read data corresponding to the area in Figure 1, and Figure 3 shows the read data in Figure 2 binarized using different thresholds. FIG. 4 is processed data obtained by performing a logical operation on the binary data shown in FIG. 3.

To explain in more detail, FIG. 2A is read data corresponding to a binary area consisting of line drawings such as type characters, and the density level changes from a dark part to a light density part, or vice versa. is changing rapidly. On the other hand, FIG. 2B shows read data corresponding to a halftone area consisting of a gradation image such as a photograph, and the density level changes relatively gently.

FIG. 3 C9D shows the read data of FIG. 2 A at different threshold values T1. It is binarized data that was binarized with King 2,
Even if the threshold values are significantly different, there is almost no change in the binarized data. On the other hand, FIG. 3 C9D is binarized data obtained by binarizing the read data of FIG. 2B using the thresholds T1 and T2, respectively, and the binarized data changes greatly due to the change in the thresholds.

Therefore, by performing a logical operation on two types of binary data obtained by changing the threshold value and obtaining the processed data after the operation, it is possible to determine whether the above-mentioned reading area is a binary area or a halftone area. I can do something.

In other words, if a logical operation is performed on the two types of binarized data obtained by binarizing with the above thresholds T and T2 and an exclusive OR is obtained, only the portions where the levels of the two binarized data differ are 1" level, so all you need to do is count the number of 11111 levels and compare the count value with a preset reference value. If it is less than the reference value, it is determined that it is in the binary area, and if If so, it can be determined that the area is in a halftone area.

FIG. 5 is a block diagram showing an image processing apparatus implementing the present invention.
2) Expose the original (3) above, guide the reflected light from the original (3) to the CCD line sensor (6) through the mirror (4) and lens (5), and convert the output signal of the CCD line sensor (6) into Area discrimination unit (applies force. Area discrimination unit (force applies) converts the output signal of CCD line sensor (6) into digital data by A/D converter (8) and applies different reference levels. By applying the binary signal from the comparator (9)00) to the exclusive OR gate (11), both
Obtain the exclusive OR of the digitized signals, count by the "1" level signal device (12) in this processed data, and apply the count value of the counter (12) to the comparator (13). Compare with the reference value applied in advance to the comparator (13),
Depending on whether the output signal of the comparator (13) is at the "'O" level or the "1" level, it can be determined whether the output signal is in the binary region or the halftone region.

Note that the present invention is not limited to the above embodiments, and for example, as shown in FIG.
By inverting the digitized data and obtaining a logical sum with the other binary data, and counting the II OI+ level signal in this processed data, area discrimination can be performed. As shown in (14), the discrimination result obtained by performing the above discrimination process only on one line of read data within the discrimination area of MXN can be used as the discrimination result of the entire discrimination area of MXN, and other Various design changes can be made without changing the gist of the invention.

<Effects> As described above, the present invention binarizes read data in a predetermined document area using two different threshold values, and
By performing logical operations on the digitized data, we obtain processed data in which the mutually different parts of both binarized data are at different levels from the remaining parts. The number is counted, and it is possible to determine whether the document area is a binary area or a halftone area depending on the number of counts. In comparison, the required memory can be reduced, and the determination operation can be performed quickly.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the area to be discriminated, Figure 2 is a diagram showing the read data corresponding to the area in Figure 1, and Figure 3 is a diagram showing the read data in Figure 2 that has been binarized using different thresholds. Figure 4 is a diagram showing digitized data, Figure 4 is a diagram showing processed data subjected to logical operations, Figure 5 is
The figure is a block diagram of an image processing device. (6)...CCD line sensor, (9) (10)
(13)...Comparator, (12)...Counter, Patent applicant: Sanda Kogyo Co., Ltd.

Claims (1)

[Claims] 1. By binarizing the read data in a predetermined area of the document using two mutually different threshold values and performing a logical operation on the obtained binarized data, the two binarized data are mutually divided. Processed data is obtained in which a different level part is set to a different level from the remaining part, and the "0" level or ゛'1 in this processed data is
``An area discrimination method that counts the number of levels and determines whether it is a halftone area or a binary area based on the number of counts. 2. A logical operation inverts one binary data and inverts the other two. 3. The area determination method according to claim 1, wherein the logical operation is an exclusive range of both binary data.