KR100472444B1 - Method and apparatus for managing shading data for scanning - Google Patents

Abstract

A shading data management method and apparatus for scanning is disclosed. The method includes a close-type image sensing unit having a plurality of sensors for reading an original, comprising: obtaining an average value of pixel values sensed by each sensor and storing average values of the sensors as black shading data; The image of the original is corrected using the black shading data. Therefore, minimizing the shading data and storing it in the ROM reduces the capacity of the ROM, reducing the production cost of the scanner, reducing the size of the scanner, and eliminating the cumbersome problem of obtaining shading data each time a document is scanned. That is, it has an effect that contributes to the simplicity of shading processing and the simplicity of memory operation.

Description

Method and apparatus for managing shading data for scanning

TECHNICAL FIELD The present invention relates to scanning and, more particularly, to a shading data management method and apparatus for managing shading data for scanning.

The conventional shading data management method reads the characteristic of the light quantity variation of each sensor inside the contact image sensor (CIS) at the time of initialization of the product, stores it in the memory, and stores the image by a given algorithm. Use to correct. Here, conventional shading data management methods for correcting deviations according to inherent light quantity characteristics of each sensor in the CIS to realize optimal image quality generally include a white shading method and a black shading method. ) Method.

The white shading method corrects light characteristics of the CIS, and reads a white document and stores all pixel values in a memory such as RAM. In addition, the black shading method corrects the dark characteristics of the CIS, and it is ideal to read the black original, but in reality, it is difficult to obtain the black original. Store in the same memory. At this time, the total pixel values obtained and stored by the white and black shading methods are used to correct the actual data.

For example, when the resolution of an analog / digital converter (not shown) for converting the output of the CIS into a digital form is 1 to ¹² , the correction value of the N-th pixel is converted and corrected as shown in Equation 1 below.

At this time, if the CIS has 600 dpi (dot per inch) color resolution and the analog / digital converter has 12 bits of resolution, the minimum amount of shading data stored in the memory is 2 ¹² = 4096 for white shading and 12 for 1 pixel. A bit is needed. Therefore, if 600 dpi has about 5120 pixels, 5120 * 12 bytes are required. In addition, it requires about 24K bytes (= 5120 * 12 * 3) because three light sources are needed: R: Red, G: Green, and B: Blue. On the other hand, black shading requires about 8K bytes (= 5120 * 12) since the light emitting diode is off.

As a result, the above-described conventional shading data management method requires shading data to be stored in a memory such as a ROM that does not require back-up, but increases the size of the memory. The black shading data obtained by performing the first shading and storing the black shading data obtained by performing the black shading before scanning the original each time is stored in the memory such as RAM. Here, even if the black shading method is performed before the white shading method, such an uncomfortable problem still exists. In addition, since the shading method is performed before scanning the document each time, there is a problem that the processing time of the shading data is delayed.

An object of the present invention is to provide a shading data management method for scanning that can minimize and store shading data for correcting the amount of light of a close-type image sensing unit in scanning.

Another object of the present invention is to provide a shading data management apparatus for scanning for performing the shading data management method.

In order to achieve the above object, the shading data management method for scanning according to the present invention includes a close-type image sensing unit having a plurality of sensors for reading the document, the method comprising: obtaining an average value of the pixel values sensed by each of the sensors and And storing the average values for the sensors as black shading data, and correcting the image of the original using the black shading data.

In order to achieve the above object, the shading data management apparatus for scanning according to the present invention comprising a close-type image sensing unit having a plurality of sensors for reading the original, and calculates the average value of the pixel values sensed by each of the sensors And a non-volatile memory for storing the average value as black shading data, and an average value calculator for outputting the calculated average value, wherein the black shading data read from the non-volatile memory is used to correct an image of the original. It is preferable.

First, a general black and white shading operation is performed as follows. That is, in a black shading operation for correcting a dark characteristic of a close-type image sensing unit (not shown), it is ideal to read a black document, but it is difficult to obtain a black document, so that a light emitting diode (LED) is used. In the off state, all pixel values are read and stored. At this time, in the white shading operation for correcting the light characteristics of the close-type image sensing unit, the white original is read and stored in the entire pixel values. As such, the total pixel values obtained in the white and black shading operations are used to correct the output level of the close-type image sensing unit.

Hereinafter, a configuration and operation of a shading data management method for scanning according to the present invention and a shading data management apparatus for scanning according to the present invention for performing the method will be described with reference to the accompanying drawings.

FIG. 1 is a flowchart illustrating a method of managing shading data for scanning according to the present invention, and includes obtaining and storing average values of pixel values of each sensor (10th and 12th steps).

FIG. 2 is a block diagram of a preferred embodiment of an apparatus for managing shading data according to the present invention, which performs the method for managing shading data shown in FIG. 1, and includes an average value calculator 20 and a nonvolatile memory 22. As shown in FIG.

FIG. 3 is a block diagram of a sensing array included in the CIS of the scanner, and includes first, second, third, ..., and N-th sensors 40, 42. , 44, ... and 46). Here, each of the sensors 40, 42, 44, ... or 46 may be implemented as a chip.

The shading data management method according to the present invention is performed in a scanner (not shown), and the shading data management apparatus shown in FIG. 2 may be included in the scanner. Here, the scanner includes a close-type image sensing unit having a plurality of sensors 40, 42, 44, ..., and 46 shown in FIG.

The average value calculator 20 shown in FIG. 2 is input through the input terminal IN1 and the first, second, third, ... and N-th sensors 40, 42, 44, ..., and 46 The average value of the sensed pixel values is calculated in each case, and the calculated average value is output to the nonvolatile memory 22 (step 10). For example, when the number of pixels existing in the entire document is 5120, the first sensor 40 shown in FIG. 3 senses 1 to 256 pixels, and the second sensor 42 is 257 to 512. The pixels are sensed, the third sensor 44 senses 512 to 767 pixels, and the N-th sensor 46 senses 4865 to 5120 pixels. As such, each sensor 40, 42, 44,..., Or 46 serves to sense 256 pixels. In this case, the average value calculator 20 obtains an average value of 256 pixel values in each of the sensors 40, 42, 44,..., And 46.

After the tenth step, the nonvolatile memory 22 stores the average values input from the average value calculator 20 as black shading data and outputs the stored results through the output terminal OUT (step 12). Here, the nonvolatile memory 22 refers to a memory which does not erase its stored data even when the power supply to the scanner including the apparatus shown in FIG. 2 is cut off. Under the foregoing assumption, the nonvolatile memory 22 stores N average values as black shading data. For example, if one average value can be represented by 12 bits, black shading data of 12N bits may be stored in a nonvolatile memory 22 such as a ROM. Therefore, when N = 20 and depending on the conventional shading data management method, the capacity of the black shading data, which is 5120 * 12 bits, may be reduced to 240 bits.

On the other hand, the black shading data output through the output terminal OUT is used to correct the image of the original along with the white shading data. In other words, the scanner corresponds to black shading data output through the output terminal OUT, that is, pixels corresponding to the sensors 40, 42, 44, ... or 46 corresponding to the average values, respectively (256 pixels under the above-described assumption). The image of the original is corrected.

As a result, the black shading data obtained by the shading data storage method according to the present invention described above is used to correct the dark characteristic deviation between the sensors 40, 42, 44, ..., and 46 shown in FIG. Lose.

FIG. 4 is a general diagram of a scanner corresponding to another exemplary embodiment of the shading data management device shown in FIG. 2, which includes a central processing unit 60, a read only memory (ROM) 62, and a read access memory (RAM). Memory (64), Image Processing Unit (66), Contact Image Sensor (CIS) (68), Analog to Digital Converter (ADC: 70) and Bus 72 It is composed.

CIS 68 shown in FIG. 4 includes first, second, third, ..., and Nth sensors 40, 42, 44, ..., and 46 shown in FIG. It reads the original through the terminal IN2 and outputs the read result. The ADC 70 converts the read result of the analog form input from the CIS 68, that is, all the pixel values into the digital form, and outputs the converted read result of the digital form to the image processor 66. At this time, the image processing unit 66 processes the read result of the digital form, that is, the image image data, and outputs the processed result to the central processing unit 60 via the bus 72.

The central processing unit 60 shown in FIG. 4 performs the tenth step shown in FIG. 1, controls the overall operation of the scanner, and controls the shading data input from the ROM 62 through the RAM 64. It also serves to correct the image of the original. That is, the central processing unit 60 illustrated in FIG. 4 serves as the average value calculator 20 illustrated in FIG. 2.

In this case, the ROM 62 performs a twelfth step and stores a system program. That is, the ROM 62 corresponds to the nonvolatile memory 22 shown in FIG. The RAM 64 also serves to buffer various data. For example, the RAM 64 provides shading data input from the ROM 62 via the bus 72 to the central processing unit 60 via the bus 60. Here, the data stored in the ROM 62 continues to be stored even if the power supply to the scanner shown in FIG. 4 is cut off, while the data stored in the RAM 64 is erased when the power supply is cut off.

As described above, the shading data management method and apparatus for scanning according to the present invention minimizes the black shading data for correcting the amount of light of the close-type image sensing unit and stores the ROM in the ROM, thereby reducing the capacity of the ROM, thereby making a scanner. It can reduce costs, reduce the size of the scanner, and eliminate the hassle of having to obtain shading data every time a document is scanned, that is, contribute to simplifying shading processing and simplifying memory operation.

1 is a flowchart illustrating a shading data management method for scanning according to the present invention.

2 is a block diagram of a preferred embodiment of an apparatus for managing shading data according to the present invention for performing the method of managing shading data shown in FIG.

3 is a block diagram of a sensing array included in a close-type image sensing unit of a scanner.

4 is a general diagram of a scanner corresponding to another preferred embodiment of the shading data storage device shown in FIG. 2.

Claims (2)

In the shading data management method for scanning comprising a close-type image sensing unit having a plurality of sensors for reading the document, Obtaining an average value of pixel values sensed by each of the sensors; And Storing the average values for the sensors as black shading data, Shading data management method for scanning, characterized in that for correcting the image of the document using the black shading data. In the shading data management apparatus for scanning comprising a close-type image sensing unit having a plurality of sensors for reading the document, An average value calculator for calculating an average value of pixel values sensed by each of the sensors and outputting the calculated average value; And A non-volatile memory for storing the average values as black shading data, And the black shading data read out from the non-volatile memory is used to correct an image of the original.