JP2003338920A - Image pickup apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically segment a manuscript region even in the case of a white manuscript such as a business card. <P>SOLUTION: The operating method of the image pickup apparatus comprises a process for obtaining entire surface image data for picking up the entire pickup range on the platen, a process for detecting a black sheet for covering the entire pickup range on the platen, an identification process for identifying a rectangular manuscript region from the entire image data, and a process for obtaining image data at a manuscript region by segmenting the image of the rectangular manuscript region being identified by the identification process from the entire image data. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading device.

[0002]

2. Description of the Related Art In an image reading apparatus, when a user sets a plurality of originals on a platen, the positions and sizes of the plurality of originals placed on the platen are automatically detected and the originals are cut out. There is a technology to perform (Japanese Patent Application No. 2001-2
35055).

FIG. 6 is a flowchart for explaining the operation of the TWAIN driver in the multi-scan mode according to the conventional technique. In step S601, the entire surface of the platen is read in color, and an 8-bit color image of each RGB color is acquired on the entire surface of the platen. In step S602, a monochrome binary image is created from the 24-bit color image of the entire surface of the document table acquired in step S601. The monochrome binary image has 0 when each pixel value is white and 1 when each pixel value is black. Here, in the conversion to a monochrome binary image, first, an 8-bit gray image is created by using the value of the G component for the RGB information of each pixel value of the 24-bit color image. Next, the value of the G component is compared with a certain threshold value, and if it is more than the threshold value, each pixel value is converted into white, and if it is less than the threshold value, each pixel value is converted into a black and white binary image. When an image is read without placing the original on the platen, the white part on the back of the platen is read, and the G value of this part is 8 bits and is 255 (0xF
F). G component of normal photo manuscript is 0-22
It is distributed between 0. Therefore, if the threshold value is set to 240 and binarized, a portion of the photographic document becomes black. FIG. 7A is a gray image before binarization. (B) is a black and white image after binarization with the threshold value 240. In step S603, the number and position of photographs are detected from the monochrome image created in step S602. The black area is determined as the original area. Figure 7
In the case of (b), since two originals are placed, the position (coordinates at the upper left of the photograph) and size (width and height of the photograph) of each original are calculated. In step S604, the number of originals and the position values obtained in step S603 are used to cut out the originals from the color image scanned in step S601. In S605, S
The inclination of each original cut out at 604 is corrected. S606
Then, the image is passed to the application compatible with TWAIN.

In this way, the TWAIN driver can automatically detect the positions and sizes of a plurality of photo originals placed on the original table, cut out the respective originals, and pass them to the application.

[0005]

However, in this method, since the original area is automatically cut out by utilizing the density difference between the original table cover (white) and the original area, a white original such as a business card or a receipt is extracted. There was a drawback that the automatic cutout of might not work.

[0006]

In an image reading method for reading an image of a document placed in a rectangular reading range between a platen cover and a transparent platen, an entire surface of the reading range on the platen is read. A step of obtaining image data, a step of detecting a black sheet covering the entire reading range on the original table, an identification step of identifying a rectangular original area from the entire surface image data, and a binary image by inverting the entire area image data Process of
There is a step of cutting out the image of the rectangular original area identified in the identifying step from the whole surface image data to obtain image data of the original area.

[Embodiment 1] FIG. 1 is a block diagram showing a configuration of a document reading unit of an image reading apparatus and a host computer. In FIG. 1, reference numeral 200 is a document reading unit, 100 is a host computer for controlling the image reading device 200 and displaying and storing an image from the document reading unit 200.

The document reading unit 200 uses a contact image sensor (hereinafter referred to as CIS) as an image sensor for scanning a document. In this type, R, G, which are color components for irradiating the document surface with light,
Since the B LEDs are sequentially switched and used, the image data is read in order of each color component for each line.

In the document reading unit 200, 2
Reference numeral 01 is a CIS (contact image sensor), and an LED 202 which is a light source is also integrated. CI
While S201 is being conveyed in the scan direction along the original glass, the LED control circuit 203 causes RGB to be set for each line.
By switching the LEDs 202 of the respective colors to be turned on, it is possible to read the original placed on the original glass as a color image of RGB line sequential.

The AMP 204 is an amplifier that amplifies the signal output from the CIS 201. Reference numeral 205 denotes an A / D converter that performs A / D conversion of the amplified output to obtain an 8-bit digital output, for example. Shading RAM
Data 206 for shading correction used in the calibration process is stored. The calibration is a process of generating black shading data and white shading data that serve as a reference of tint in order to perform accurate color reading. The shading data is generated by reading the black and white marks on the back of the platen glass and performing arithmetic processing on those data by the host computer 100. Host computer 10
0 indicates data for shading correction on hard disk 1
Save in 03. When the host computer 100 initializes the document reading unit 200, the shading correction data is transmitted to the shading RAM 206. The shading correction circuit 207 performs shading correction of the read image signal based on the data of the shading RAM 206. Peak detection circuit 2
Reference numeral 08 is a circuit for detecting the peak value in the read image data for each line. When reading images, CIS
It is used for calibration processing and the like for adjusting and determining the lighting section of each LED color.

The gamma conversion circuit 209 performs gamma conversion on the image data read according to the gamma curve sent from the host computer 100.

The buffer RAM 210 is a RAM for temporarily storing image data in order to match the timing in image communication with the host computer. The packing / buffer RAM control circuit 211 has an image output mode preset by the host computer 100 (binary, 8-bit multi-value, 24-bit multi-value, etc.).
After performing the packing process according to the above, a process of writing the data in the buffer RAM 210 and a process of reading the image data from the buffer RAM 210 to the interface circuit 212 and outputting the image data to the host computer 100 are performed.

The interface circuit 212 exchanges control signals and control data with the personal computer 100.
Communicate image data. Interface circuit 21
2 includes types such as a parallel interface, a SCSI interface, a USB interface, and an IEEE 1394 interface. A motor drive circuit 213 is a circuit that drives the motor 214 at a speed instructed by the host computer. Motor 2
By driving 14 times, the CIS 201 is transported and the scan processing is executed. The motor drive speed is proportional to the image data output speed. Set the motor speed at the start of reading and do not change it during reading.

In the host computer 100, 10
Reference numeral 1 is a CPU for performing various calculations. 102 is a RAM used as a work area by the operating system or program. A hard disk 102 stores an operating system and programs. Reference numeral 104 is a monitor, and 105 is an input device such as a mouse and a keyboard. An interface unit 106 connects an external device such as a document reading unit to the host computer 100, and includes a parallel interface, a SCSI interface, a USB interface,
There are types such as IEEE 1394 interface. The appearance of the image reading device is shown in FIG. 251 in FIG.
A set 251 is a document table cover for pressing the set document and has a white color. Reference numeral 252 represents a document table on which a document is placed, 253 is a document reading unit for reading the set document, and 254 is a document alignment mark to be aligned when the document is set. Platen 25
A document is placed on the document 2 and the document is read by the document reading unit 200.

FIG. 3 is a diagram showing the structure of a program for controlling the image reading apparatus. 301 is TWAIN
An application conforming to the standard reads an image from the document reading unit 200 via the TWAIN driver 302 and displays it on the monitor 104. It has a function of processing and saving an image according to a user's instruction. TWAI
N driver 302 conforms to the TWAIN standard
The image from the image reading device 200 is passed to the corresponding application, and a unique GUI (graphic user interface) is displayed. The GUI is for previewing, specifying the crop area for the preview image, setting the resolution, and reading mode (binary, 8-bit multi-valued, 2
It has a function of setting (4 bit multi-value, etc.) and setting of color adjustment such as gamma correction.

The device driver 303 accesses the control register of each module of the document reading unit 200, controls shading, sets the motor speed according to the resolution and crop range, and reads the gamma correction data from the TWAIN driver. Two
The transmission process to 00 and the flow control for image reading are performed. The port driver 304 includes a parallel interface, a SCSI interface, a USB interface,
Communication control with the document reading unit 200 is performed according to an interface such as an IEEE 1394 interface. 305 is an operating system (OS) of the host computer 100, such as Windows (registered trademark)
Is.

FIG. 4 shows a black sheet used when scanning a white document such as a business card. One side is a business card folder and one side is a paper folder. FIG. 4A is a diagram of the business card folder side. In the figure, reference numeral 401 is a black background, and its size is substantially equal to the maximum reading area of the image reading apparatus. Reference numeral 402 denotes a business card folder, which is a transparent member and is fixed to the base 401 at the upper and lower ends and the left end. In the business card folder 402, the base 401 is attached at five places in one row and in two rows. Business cards 403 and 404 are inserted in the business card folder. Insert the business card into the business card folder from the right edge of the business card folder. A mark 405 indicates a position on the document table 252 to be set when a black sheet is used. The black sheet is set on the document table 252 so as to match the document position alignment mark 254. 406 is T
The WAIN driver 302 is an area for determining whether a black sheet is set on the document table. TWA
The IN driver scans the entire surface of the platen, and if this area is black, it is determined that a black sheet is set.

FIG. 4B is a view of the black sheet on the side of the paper folder. In the figure, 411 is a black background, and its size is almost equal to the maximum reading area of the image reading apparatus. 412 is a paper folder, which is a transparent member,
The upper and lower ends and the left end are fixed to the base 411. Insert the paper from the right edge of the paper folder. Reference numeral 413 is a mark indicating which position on the document table 252 is set when a black sheet is used. The black sheet is set on the document table 252 so as to match the document position alignment mark 254. Reference numeral 414 is an area for the TWAIN driver 302 to determine whether a black sheet is set on the platen. The TWAIN driver scans the entire surface of the platen, and if this area is black, it is determined that a black sheet is set.

FIG. 5 is a flow chart for explaining the operation of the TWAIN driver 303 according to the present invention in the multi-scan mode.

In step S501, the entire surface of the platen is read in color, and 8-bit color images of RGB of the entire surface of the platen are acquired.

In step S502, it is determined whether the black sheet is placed on the platen using the color image read in step S501. The determination method determines that a black sheet is placed when the area 406 or the area 414 is entirely black. In the case of 24-bit color, when the level of the G component is 60 or less, it is determined to be black. If the black sheet is placed, go to S504. If not, go to S504.
Proceed to 503.

In step S503, a monochrome binary image is created from the 24-bit color image of the entire surface of the document table acquired in step S501. The monochrome binary image has 0 when each pixel value is white and 1 when each pixel value is black. Here, in the conversion to a monochrome binary image, first, an 8-bit gray image is created by using the value of the G component for the RGB information of each pixel value of the 24-bit color image. Next, the value of the G component is compared with a certain threshold value, and if it is more than the threshold value, each pixel value is converted into white, and if it is less than the threshold value, each pixel value is converted into a black and white binary image. If an image is read without the document placed on the platen, the white part of the platen cover 251 is read, and the G value of this part is 255 at 8 bits.
(0xFF). The G component of a normal photographic document is distributed between 0 and 220. Therefore, if the threshold value is set to 240 and binarized, a portion of the photographic document becomes black. FIG. 7A is a gray image before binarization.
(B) is a black and white image after binarization with the threshold value 240.

In S504, the 24 bi acquired in S501
An 8-bit gray image is created by using the G component value for the RGB information of each pixel value of the t color image. 8 bi
In the case of t gray, 255 (FFh) represents white, 0 represents black, and the values in between represent white density. Then, the 8-bit gray image is inverted in black and white. The value of a specific pixel is A (0
255), the pixel value B after black-and-white inversion is obtained by the following equation.

B = 255-A FIG. 8A shows an image of an image in which three business cards are set in a business card folder before being inverted. FIG. 8B is an image after being inverted.

In step S505, the image that has been black and white inverted in step S504 is binarized with a threshold value 50.

In S506, the number and position of photographs are detected from the black and white image created in S503 or S505. The black area is determined as the original area. In the case of FIG. 7B, 2
Since one original is placed, the position (coordinates of the upper left of the photograph) and size (width and height of the photograph) of each original are calculated.

In step S507, the document number and position values obtained in step S506 are used to cut out the document from the color image scanned in step S501.

In step S508, the inclination of each original cut out in step S507 is corrected.

In step S509, the image is passed to the TWAIN-compliant application 301.

In this way, the TWAIN driver 30
2 automatically detects the positions and sizes of a plurality of photo originals placed on the original table 251, and cuts out each original,
Can be passed to the application.

[0031]

As described above, according to the present invention,
By detecting a black sheet covering the entire reading range on the platen and cutting out the original, it is possible to automatically cut out the original even for a white original such as a business card or a receipt.

[Brief description of drawings]

FIG. 1 is a diagram showing an image reading apparatus according to the present invention.

FIG. 2 is a block diagram showing a circuit configuration of an image reading apparatus according to the present invention.

FIG. 3 is a diagram showing a configuration of control software of the image reading apparatus to which the present invention is applied.

FIG. 4 is a diagram showing configurations of a business card folder and a paper folder of a black sheet according to the present invention.

FIG. 5 is a flowchart for explaining the operation of the control software of the image reading apparatus to which the present invention is applied.

FIG. 6 is a flowchart illustrating a conventional image reading processing operation.

FIG. 7 is a diagram for explaining image binarization processing.

FIG. 8 is a diagram for explaining the black and white reversal processing of an image.

[Explanation of symbols] 101 ... Platen cover 102 ... manuscript table 103 ... Platen reading unit 104: Document alignment mark

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Claims (4)

[Claims] 1. An image reading method for reading an image of a document placed in a rectangular reading range between a platen cover and a transparent platen, wherein full surface image data for reading the entire reading range on the platen is obtained. Steps, a step of detecting a black sheet covering the entire reading range on the platen, an identification step of identifying a rectangular original area from the entire surface image data, and an image of the rectangular original area identified in the identification step. An image reading apparatus comprising a step of cutting out the entire surface image data to obtain image data of a document area. 2. The image reading device, wherein the black sheet has a transparent business card folder. 3. The image reading device, wherein the black sheet has a transparent paper folder. 4. An image reading apparatus which secures a sheet discrimination area on the black sheet.