JPH10200740A - Image processing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the time required for processing to set a threshold level to a proper value in the case that the threshold level to binarize multi-value image data is set freely and to reduce considerably a capacity of a memory required for the processing. SOLUTION: Image data read with low resolution by an image input device 21 are stored in a 1st area in a temporary storage means 23 and binarized by an image binarizing means 24 based on a threshold level set by an instruction input means 27. When a worker sees binary data displayed on a display means 25 and enters an instruction 'OK', the image input device 21 reads the data with high resolution.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a binary image processing system provided with an image input device and a computer for performing image processing, and more particularly to easily and quickly specify a threshold value for converting an image into a monochrome binary image. The present invention relates to an image processing device that can be used.

[0002]

2. Description of the Related Art Conventionally, the following method has been generally used as a method for taking an image from an image input device into a computer as a binary image.

(1) After taking in a multi-valued image from an image input device, binarization is performed with an arbitrary threshold value.

(2) If the image input device has a binarization function, a threshold value for binarization is given to the image input device in advance, and the binarized image is taken in.

(3) Binarization is performed while taking in a multi-valued image from an image input device.

[0006]

In the method (1), since multi-value data is taken into the computer, the capacity of a storage medium is increased. Further, high-resolution multi-value data is repeated, and the threshold value is changed to perform binarization, which takes a long processing time.

In the methods (2) and (3), if the captured image is not the expected image, the image must be read again from the image input device, which takes time.

The present invention reduces these wasted time,
An object of the present invention is to provide a method for accurately capturing a binary image from an image input device with a small storage capacity.

[0009]

In order to solve the above-mentioned problems, the present invention provides a low-resolution multi-value image input means, a high-resolution binary image input means, a threshold value specifying means for binarization, It has a means for displaying a binary image, a means for binarizing a multi-valued image by a threshold value, and a means for storing an image. By displaying the converted image, it is possible to determine the threshold value at the time of inputting the actually required high-resolution image by looking at the displayed image. In addition, since a low-resolution multi-value image and a high-resolution binary image are handled, the storage capacity can be reduced.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below.

FIG. 1 is a block diagram of an image processing apparatus according to a first embodiment of the present invention, wherein 1 is a CPU for controlling the apparatus and performing various data processing, and 2 is fixed information such as a program. Is a ROM that stores
Is the RA in the program in the ROM 2 or the external storage device.
Processing is performed according to the program copied to M3. Reference numeral 3 denotes a RAM for storing various data, an image data area 4 for storing image data read from the image scanner 7 as multi-value data or binary data, and a CR.
It has a display data area 5 for storing bitmap data to be displayed at T9, and a program area 11 for storing program data. Reference numeral 6 denotes an input device such as a keyboard or a mouse, 8 denotes an external storage device such as a hard disk or a magneto-optical disk, and 10 denotes a printer.

FIG. 2 is a functional block diagram of the image processing apparatus shown in FIG. In the figure, reference numeral 21 denotes an image input device which optically reads a document, converts it into a digital signal, and outputs it as image data, and is realized by the image scanner 7 (a digital camera or the like is also possible). Reference numeral 22 denotes an image control unit that performs image processing such as setting resolution and the like for the image input device 21 and binarizing multi-valued image data output from the image input device 21. ROM 2 or program area 1
1 is executed by executing the program. 2
Reference numeral 3 denotes a temporary storage unit for storing the image data processed by the image control unit 22, and corresponds to the image data area 4 in the RAM 3. 24 is a temporary storage means 23
2 for binarizing multi-valued image data stored in
A value conversion means, which is the same as the image control means 22;
Is executed by executing a program in the ROM 2 or the program area 11. 25 is a display unit realized by the control of the CPU 1, the display data area 5 in the RAM 3, and the CRT 9 (a display device such as a liquid crystal display is also possible).
26 is a storage unit realized by the control of the CPU 1 and the external storage device 8, and 27 is an instruction input unit realized by the control and the input device 6 of the CPU 1.

The image input device 21 converts the original image into RG
The signal is decomposed into signals of three primary colors B and output as multivalued image data digitized into data of 8 bits per pixel or 12 bits per pixel for each color component. The image control means 2 determines whether to use 8-bit data or 12-bit data.
The number is set by 2. In the case of 8 bits, the multi-valued image data has 256 tones, and in the case of 12 bits, it has 4096 tones. Further, the image input device 21 is 150 dp in the main scanning direction.
i, 300 dpi, 600 dpi, and three sub-scanning directions, 150 dpi, 300 dpi, 60 dpi
It corresponds to five resolutions of 0 dpi, 1200 dpi, and 2400 dpi. The resolution to be read in the main scanning direction and the sub-scanning direction is determined by the image control unit 22.
Is set by

The image control means 22 has a function of making various settings for the image input device 21 and a function of synthesizing multi-valued image data of three primary colors of RGB output from the image input device 21 to obtain one image.
It has a function of generating multi-valued image data representing one gray value and a function of binarizing the generated multi-valued image data representing one gray value.

When synthesizing data of the RGB primary colors, R
Convert the data of GB into data of L * a * b * coordinate system,
The L component data is output as multi-valued gray value image data. Binarization of multi-valued image data is
Based on the threshold value set by the instruction input means 27,
This is performed according to the flowchart of FIG. Here, first, a value set from the instruction input means 27 is set as a threshold value (step 31), and one pixel is read from multi-valued image data to be binarized (step 32). The pixel value is compared with the threshold value (step 33). If the pixel value is larger, the pixel value is output as a pixel of value "1" (step 34). If the pixel value is smaller, the pixel value is output as a pixel of value "0" (step 34). Step 35). The above processing is performed on all pixels of the multi-valued image data. This threshold value is limited to a value from “1” to “255” for 8-bit data, and to a value from “1” to “4095” for 12-bit data.

The image binarizing means 24 includes a temporary storage means 23
After reading multi-value image data from and binarizing it,
Write to the temporary storage means 23. The binarization method is the same as that of the image control unit 22. The display means 25 reads out the binary image data stored in the temporary storage means 23, converts the data into display data, and performs display. The storage means 26 stores the binary image data stored in the temporary storage means 23,
This is stored together with the file name as an image file. The instruction input unit 27 inputs an instruction from an operator to the image control unit 22, the image binarization unit 24, and the storage unit 26.

The operation of the image processing apparatus according to the first embodiment configured as described above will be described below with reference to the flowchart of FIG.

Here, from the instruction input means 27 to the image control means 22, the resolution is 600 dpi and the number of gradations is two.
It is assumed that the setting is made so as to have 56 gradations (8 bits).

First, when an image input instruction is input from the instruction input means 27, the image control means 22
1 is requested to read the document image at the lowest resolution 150 dpi and 256 gradations that the image input device 21 can support (step 1). The image input device 21 that has received the reading request has a resolution of 150d
The image data is read at a high speed at pi, and each of the RGB primary colors is converted into 8-bit digital data and output to the image control unit 22 (step 2). The image control means 22 combines the data of the three primary colors RGB to generate multi-value image data having one gray value, and temporarily stores the multi-valued image data.
(Step 3).

Here, the image binarizing means 24 waits for setting of the threshold value from the instruction input means 27 (step 4), and reads out multi-valued image data from the first area in the temporary storage device 23. The binarization process is performed based on the set threshold value, and the obtained binary image data is written to the second area in the temporary storage means 23 (step 5). When the binarization is completed, the display unit 25 reads out the binary image data from the second area in the temporary storage unit 23, converts the binary image data into display data corresponding to the display resolution, and displays the data (step 6). .

Here, the operator is caused to confirm whether or not the data displayed on the display means 25 is an expected image by the instruction input means 27 (step 7), and an input indicating that the data is as expected is obtained. If it is, the process proceeds to step 8. If there is an input indicating that the result is not as expected, the process returns to step 4. When the process returns to step 4, the subsequent processing is performed after waiting for the setting of the threshold value from the instruction input means 27 again.

In step 8, the image binarizing means 24 sets the last set threshold value to the image control means 22. Next, the image control unit 22 requests the image input device 21 to read the original image at a preset resolution of 600 dpi and 256 gradation levels, and receives the read request. The device 21 reads at a resolution of 600 dpi, converts each of the RGB primary colors into 8-bit digital data, and outputs the digital data to the image control unit 22. In the image control means 22, RG
The multi-valued image data having one gray value is generated by synthesizing the data of the three primary colors B, and the multi-valued image data is binarized based on the threshold set in step 8 to temporarily Writing to the third area in the storage means 23 (step 9). Further, the display means 25 reads the binary image data from the third area in the temporary storage means 23, converts the binary image data into display data according to the display resolution, and displays the data (step 10). After the display is made,
Waiting for a file saving instruction from the instruction input means 27, the storage means 26 stores the second area from the third area in the temporary storage
The image data of the value is read and stored as an image file together with the file name input from the instruction input means 27.

As described above, in the image processing apparatus according to the first embodiment, the multivalued image data read once at a low resolution is binarized while changing the threshold value until desired binary data is obtained. Is repeated to determine an appropriate threshold value, and in order to perform reading at a desired high resolution, the time required for adjusting the threshold value of binarization can be greatly reduced.

During the adjustment of the threshold value, the low-resolution multi-valued data and its binarized data are processed. During the processing of the high-resolution data, the high-resolution binary data is temporarily stored. Since it is not necessary to temporarily store the multivalued data, the memory capacity for temporarily storing the image data can be greatly reduced.

The designated resolution is N, the low resolution for reading the threshold value adjustment is n, the data amount per pixel of multi-valued image data is m bits, and the binary image data is 1 bit.
The data amount per pixel is 1, the image size is w inches wide,
Assuming that the height is h inches, the data amount of the multi-valued image data when reading at low resolution is (n × m × w × n × h ÷ 8) bytes, and the data amount when binarizing the data is (n × w × n
× h ÷ 8) It is obtained in bytes. Further, the data amount of the multi-valued image data when read at a high resolution is (N × m × w
(× N × h ÷ 8) bytes, and the data amount when the binarization is obtained is (N × w × N × h ÷ 8) bytes. Therefore, in the case of the first embodiment, assuming that the document is 1 inch square, the memory capacity required during the threshold value adjustment is the same as that of the multi-valued image data read at 150 dpi (low resolution). 22,500 bytes of data and 2
Total 2 of the data amount of the valued data 2,813 bytes
This is 5,313 bytes. Also, specified resolution (high resolution)
The capacity of the memory required for reading data is 45,000 bytes of image data after binarization. Therefore, the memory capacity required for adjusting the threshold value using the high-resolution multi-value data is 360,000 bytes (the amount of high-resolution multi-value image data) +45,
000 bytes = 405 compared to 405,000 bytes
000 bytes− (22,500 bytes + 2,813 bytes + 45,000 bytes) = 334,6878 bytes of memory can be reduced.

When this is represented by a general formula, the formula shown in (Equation 1) is obtained.

[0027]

(Equation 1)

That is, the data amount m per pixel is large (the number of gradations is large) and the designated resolution N (in the case of high resolution)
And the lower resolution n (resolution at the time of adjusting the threshold value), the more the memory capacity can be reduced.

FIG. 5 is a functional block diagram of a second embodiment according to the present invention. Reference numeral 41 denotes an image input device which optically reads an original, converts the original into a digital signal, and outputs it as image data. This is an image control unit that sets the resolution and the binarization threshold value for the input device 41. In the second embodiment, the image control means 42 does not have a function of binarizing multi-valued image data or a function of converting RGB data to gray data, and
The processing is done on the side. Therefore, the image control unit 42 sets the resolution and the number of gradations for the image input device 41, and also sets whether to output the read data as multi-valued data or to convert the read data into binary data. In addition, portions other than the image input device 41 and the image control means 42 are the same as those in the first embodiment in both configuration and processing, and thus description thereof is omitted here.

Although the first and second embodiments are directed to color image data, it is apparent that the same effect can be obtained by using an image input device for monochrome image data. is there.

[0031]

As described above, according to the present invention, at the time of low-resolution input, a read multi-valued image is binarized by a specified threshold value to display a binarized image. Of the threshold value at the time of inputting the high-resolution image necessary for the image processing can be determined. In addition, since a low-resolution multi-value image and a high-resolution binary image are handled, the effect of requiring a small storage capacity is achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an image processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a functional block diagram of the image processing apparatus.

FIG. 3 is a flowchart of a binarization process in the image processing apparatus.

FIG. 4 is a flowchart showing the operation of the image processing apparatus.

FIG. 5 is a functional block diagram of an image processing apparatus according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 Image input device 22 Image control means 23 Temporary storage means 24 Image binarization means 25 Display means 26 Storage means 27 Instruction input means

Claims (1)

[Claims] A first reading unit that reads an image of a document at a first resolution and outputs the image as multi-valued image data; and reads the image of the document at a second resolution lower than the first resolution. Second reading means for outputting as resolution multi-value image data, storage means for storing the low-resolution multi-value image data, and binarization of the low-resolution multi-value image data stored in the storage means Threshold value setting means for setting a threshold value for performing the threshold value setting, and a first threshold value binarizing the low-resolution multi-value image data stored in the storage means according to the threshold value set by the threshold value setting means. Value conversion means, display means for displaying the image data binarized by the first binarization means, and input means for inputting whether or not the binary image data displayed on the display means is appropriate When the binary image data is properly input by the input unit, the image of the original is read by the first reading unit, and the obtained multi-value image data is set by the threshold value setting unit. An image processing device comprising: a processing unit that binarizes the image based on a threshold value.