JPH0470165A - Picture reader - Google Patents

Abstract

PURPOSE:To improve efficiency for compressing a picture data at an external device by outputting a multi-level picture data after converting it. CONSTITUTION:A photoelectric conversion circuit A and an A/D conversion circuit B irradiate an original by a light source, output original picture information as data signals at multi-value levels by photoelectric conversion and A/D conversion, and rearrange the outputted data signals according to a prescribed table for conversion. In this case, preferably, a data table for conversion input circuit D is provided to input the data table for conversion as the base of executing conversion from the external device or the like, and a data table for conversion output circuit E is provided to output the data table for conversion to the outside. Then, the data table for conversion is inputted from the external device, and the multi-level picture data are converted and outputted. On the other hand, at the external picture processor, a prescribed picture processing is executed by using the data table for conversion outputted from this device. Thus, conversion to the picture data suitable for compression is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device that illuminates a document with a light source and outputs document image information as a multivalued data signal through photoelectric conversion.

[Prior Art] Conventionally, in this type of image reading device, the amount of data becomes large when outputting multilevel data, and the data is compressed by an external device that receives the image data and then undergoes predetermined processing. Was.

[Problems to be Solved by the Invention] However, it cannot be said that multilevel image data output from an image reading device is necessarily efficiently reduced by compression, and some images have the disadvantage that processing and storage are difficult. It was seen.

SUMMARY OF THE INVENTION In view of the above points, an object of the present invention is to provide an image reading device that is suitable for compression and is capable of outputting image data.

[Means for Solving the Problems] An image reading device according to the present invention includes a photoelectric conversion means that illuminates a document with a light source and outputs document image information as a multilevel data signal through photoelectric conversion and A/D conversion. , conversion means for rearranging the data signals output from the photoelectric conversion means based on a predetermined conversion table.

[Function] According to the present invention, a conversion means is provided inside the image reading device,
This makes it possible to convert the image data into image data suitable for compression.

〔Example〕

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the overall configuration of one embodiment of the present invention. In the figure, A is a photoelectric conversion circuit including a CCD;
B is an A/D conversion circuit, and C converts the sending image data (
D is a circuit for inputting a conversion data table, which is the basis for performing the above conversion, from an external device, etc., and E is a circuit for outputting the conversion data table to the outside. In this embodiment, a conversion data table is input from an external device to convert and output multivalued image data (a specific example of conversion will be described in detail later with reference to FIG. 6). On the other hand, an external image processing device (
(not shown) performs predetermined image processing using the conversion data table output from the image reading device.

FIG. 2 is an external perspective view of an embodiment of an image reading device to which the present invention is applied, and FIG. 3 is a diagram showing its internal configuration.

In FIG. 3, 1 is a document image reading device (hereinafter referred to as a reader). This reader is a so-called “sheet” (
In other words, 1 g of a book manuscript (not necessarily a bound book, but may be in the form of a sheet) is placed on the platen glass 17 on the document surface. is placed facing downward and illuminated by the fluorescent lamp 15a of the original illumination unit 15 of the optical scanning system. The CGD 12 is configured to form a document image on a coupling device (coupling device) 12. This CGD 12 is driven by a CCD driver 13. Reference numeral 11 denotes a control unit to be described later;
9 is a platen cover for bringing the original 18 into close contact with the platen glass 17, and 31 is a white reference plate for shading correction.

Next, FIG. 4 shows a block diagram of the main circuit configuration of the device of this embodiment. This figure shows the main circuit parts of the CCD driver 13 and control unit 11 in FIG.
A CD drive circuit, 21 is an amplifier, and 22 is an A/D converter. On the other hand, the control unit 11 includes a background density detection circuit 2.
4. Binarization circuit 25. Selector 261 Data conversion circuit 32 unique to this embodiment. Interface circuit 27 for outputting to an external device. C including ROM28A and RAM28B
P02g, a timing signal generation circuit 29, and its oscillator 30.

Next, the operation of the reader 1 according to this embodiment will be explained with reference to FIGS. 3, 4, and 5. FIG. 5 is a sequence flowchart of the reading operation. Book manuscript 1
8 is constructed so that when the platen cover 19 is opened, the original is placed on the platen glass 17 in FIG. ing.

The original illumination unit 15 of the optical system is configured such that the right end in FIG. 3 is the initial position (reference position), and the position is confirmed by an optical position sensor (not shown).

The rider 1 of this embodiment always uses an external device (not shown) (for example, a digital printer, a personal computer, etc.)
The communication of control signals with these external devices and the output of image signals from the reader 1 to the external devices are performed by the interface circuit 27 (see Fig. 4).
It is done through.

Prior to the operation of the reader 1, commands for various modes are input from an external device.
00.200, and which position on the document the image reading tilt should be made. Furthermore, a conversion data table is also input.

The CP [J2g that receives these commands is configured in advance by the timing signal generation circuit 29, selector 26, or data conversion circuit 3.
A control signal is output to 2 to set the pixel density and reading area position/size.

When a command to start reading the original is input from an external device,
First, in step S1, it is confirmed whether the document 18 is in the book position, and the CPO 211 first outputs a lamp control signal to light the lamp 15a of the document illumination unit 15 (step S2). , shading correction, and gamma correction are performed, and scanning is started in the direction of the arrow in FIG.

From the initial position of the original illumination unit 15 to the platen glass 1
There is a distance of about 2 to 3 mm from the leading edge of the original on the document 7, and during this time, the scanning speed of the optical system by a pulse motor (not shown) is controlled to be stable.

When the original illumination unit 15 reaches the leading edge of the original, the CPU 18 outputs a control signal to enable image signal output to the interface circuit 27, and the read images are sequentially displayed at 7.
It is output to an external device (step S3).

The scanning length of the optical system is uniquely determined by the number of pulses that the CPIJ 2g uses to drive a pulse motor (not shown), so the CPU 28 determines that document reading is complete when the required number of pulses is output to the motor. Then, in step S4), the lamp 15a is turned off, image signal output is disabled, and the motor is reversed, and a document reading end signal is output to an external device.

Due to the motor reversal control (step S5) of the CP [128], the original illumination unit 15 moves in the direction of the arrow in FIG. is detected (step S6), the optical system stops (step S7). If the next document reading start command is not received from the external device during the return period of the optical system, the optical system stops at the initial position and resumes operation. It ends.

Next, the operation of this circuit will be explained based on the block diagram shown in FIG. The CCD 12 on the CCD driver 13 in FIG. 3 is driven through the CCD drive circuit 23 by each timing signal generated by the timing signal generation circuit 29 on the control unit 11.

The image analog signal output from C(:I) 12 is amplified by an amplifier 21 and converted into analog/digital (A
/D) is input to the converter 22. In this A/D converter 22, the image signal is converted from an analog signal into an 8-bit digital signal using a timing signal generated by a timing signal generating circuit 29, and is output to the control unit 11.

The control unit 11 detects non-uniformity of the image signal level (referred to as shading) due to non-uniformity of the light amount of the illumination unit 15, non-uniformity of transmission of the lens 14, and non-uniformity of the sensitivity of the CCD 12 with respect to the input digital image signal. ) is electrically removed by the shading correction circuit 20.

This shading-corrected digital image signal is
The data is processed through the selector 26 and the data conversion circuit 32 into an output mode instructed by the external device, and is output to the external device through the interface circuit 27.

The external device that receives the image data compresses the data and records it in a file. Actually, when using the image file for processing, use the above conversion data table,
Convert and process again.

Next, the output of multivalued data in this embodiment will be explained using FIGS. 4 and 6.

The digital image signal output from the selector 26 (see FIG. 4) is input to the data conversion circuit 32, and is converted into a conversion data table previously set by an external device (or a conversion data table uniquely stored inside the device). The data to be sent out is rearranged using the data table (data table) and output to the interface circuit 27.

An example of the conversion (that is, data rearrangement) at this time will be described below. FIG. 6 describes a bit string of 8-bit multivalued data. In this embodiment, as shown in the figure, the number of changing bits when the density level increases by one level is defined, considering a gradual change in density when outputting multilevel data.

That is, in the conventional example, there are many changed bits (Fig. 6 (A
)) In order to deal with the fact that data compression was necessary in processing multivalued data, the compression efficiency was poor.
In this embodiment, as shown in FIG. 6(B), the compression efficiency is increased by converting the change bit to "1" when increasing the density level by one level, thereby improving the processing efficiency. It makes it possible to improve.

In addition to the embodiments described above, it is also possible to use different conversion data tables depending on the original, and furthermore, it is possible not only to improve compression efficiency but also to directly perform image processing.

[Effect of the invention 1] As explained above, according to the present invention, by converting and outputting multilevel image data (specifically, rearranging the transmission order of multilevel data), image data in an external device can be The compression efficiency of the data can be increased, thereby making it possible to improve the overall processing efficiency.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the overall configuration of an embodiment of the present invention, Fig. 2 is an external perspective view of an image reading device embodying the present invention, Fig. 3 is an internal configuration diagram thereof, and Fig. 4 is its main components. FIG. 5 is a flowchart showing the operation of this embodiment, and FIG. 6 is a diagram showing an example of data conversion in this embodiment. DESCRIPTION OF SYMBOLS 1... League (image reading device), 15... Document illumination unit, 11... Control driver, 13... CCD driver, 18... Document, 32... Data conversion circuit. Figure 1 Figure 1 Figure

Claims (1)

[Claims] 1) A document is irradiated with a light source, and photoelectric conversion and A/D conversion are performed.
A photoelectric conversion means for outputting original image information as a multilevel data signal through conversion, and a conversion means for rearranging the data signals output from the photoelectric conversion means based on a predetermined conversion table. Characteristic image reading device. 2) The image reading device according to claim 1, wherein the conversion table is input from an external device. 3) The image reading device according to claim 1, wherein the conversion table is output to an external device for image processing.