JPS63299575A - Picture input device - Google Patents

Abstract

PURPOSE:To realize the input of a halftone picture like a photo, etc., into a computer as the picture data without deteriorating the image resolution and the gradation, by converting the analog voltage signal corresponding to the variable density of an original undergone the correction of distortions into the digital picture data. CONSTITUTION:A means 20 is provided to read the variable density information on an original and produces the analog picture signals together with a distortion correcting means 60 which corrects both shading and high frequency distortions, and a digitizing circuit 62 which produces the halftone picture data from the corrected analog picture signals by a dither or CAPIX method. Thus it is possible to read the picture information of halftone on pictures, photos, etc., without deteriorating the image resolution and also to obtain the halftone picture data of a large number of gradations.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image input device capable of reading halftone image information such as photographs and paintings.

[Prior art]

In recent years, systems using computers have been developed in the printing field. That is, there are devices that edit a print image based on document data input from a keyboard or image data input from a scanner, and perform plate making based on these data.

In such a system, data is treated as binary data, so only line drawings can be processed as image data, and it is impossible to read and input halftone images such as photographs. Or even if it were possible, the resolution would be lowered or the number of gradations would be reduced, making it impossible to use it as a printed image.

[Problem that the invention seeks to solve]

This invention was made to deal with the above-mentioned circumstances,
It is an object of the present invention to provide an image input device capable of reading a halftone image having a large number of gradations without reducing the number of gradations or resolution.

[Means for solving problems]

The corrected analog image signal is dithered or CA
A halftone processor is provided for converting into halftone image data using the P I :; method.

[Effect]

According to the image input device according to the present invention, halftone image data with a rich number of gradations can be obtained without reducing resolution.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an image input device according to the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of one embodiment. This embodiment has a so-called disk top type shape. The main body 10 has a document table I2 on the top on which a document is placed with its reading surface facing downward.
and an operation panel 14 consisting of various operation switches. A document cover 16 is attached above the document table 12. The document table 12 is made of a transparent glass plate or the like, and the document is read and scanned by a CCD line sensor provided inside the main body IO.

This embodiment is broadly divided into a scanning system, a driving system, a control system, and a power supply system. The scanning system includes a CCD line sensor that reads image information, a lamp that illuminates the document, and a CCD that captures the optical image of the document.
It consists of an optical system that causes the light to enter the line sensor and capture an image. The drive system includes a pulse motor and a mechanical system that two-dimensionally scans the document by moving the optical system in the sub-scanning direction.

The control system consists of a CPU, an image processing processor, and an I/F.

In this example, the read density is "normal", "dark", "
It can be specified in 3 levels: ``thin''. The reading density means the density level state of the input image, and when "dark" is specified, the density of the input image becomes darker than the actual density.

Furthermore, the reading gradation can be selected from binary gradation or 16 intermediate gradations. Halftones are expressed using dither method or C
AP IX method (Corrclative-Dcnsi
ty-Assignn+ent ofadjacent
Pixels). This reading gradation can be changed by specifying the gradation mode. There are four gradation modes: "text mode", "photo mode 1", "photo mode 2", and "photo mode 3". "Character mode" is a binary gradation. "Photo mode 1" and "Photo mode 2" each use a different CAPIX method (here,
This is a pseudo halftone of 16 gradations based on CAPIXI and CAPIX2. "Photo mode 3" is a pseudo halftone of 16 gradations using the dither method. "Text mode" is used to read characters and figures, "Photo mode 1" is used to read ordinary photos, "Photo mode 2" is used to read printed photos, and "Photo mode 3" is used to read printed photos. Shading in the photo is used for processing. For this reason, the operation panel 14 is provided with a power switch, a concentration switch, and a mode switch.

FIG. 2 is a block diagram showing the circuit configuration.

The CCD line sensor 20 is an image processor (DIP).
P) connected to 22. The CCD line sensor 20 has 4096 pixels arranged in the main scanning direction, and has a resolution of 16
Dots/mm, B4 size (main scanning direction is 2)
It is possible to read originals up to 58 mm.

The reading speed is about 2.5 m5s in the main scanning direction and about 155 in the sub-scanning direction (the resolution in the sub-scanning direction is also 16 dots/in). The CCD line sensor 20 and lens are fixed, and the reading optical system is moved in the sub-scanning direction.

Three mirrors are used.

The DIPP 22 is a circuit that performs various corrections on the analog image signal indicating the density of the original from the CCD line sensor 20, digitizes it, and outputs it as 16-gradation data of 4 bits per pixel. DIPF'22 is connected to CPU2B via data bus 24. Also, the lamp alarm signal is sent directly to the CPU from the DIPP22.
2B.

An example of DIPP22 is HD630 manufactured by Hitachi.
There are 84.

CPU26 is PIC, PIT, PIO, PROM (8K
), RAM (32K), and S10.

An example of CP tJ 26 is Motorola's M5.
There is 0747. An operation panel 28 is also connected to the data bus 24. The operation panel 28 includes various switches and LEDs for display.

A pulse motor driver 30, a home position sensor 32, and a lamp 34 are connected to the CPU 2B. A motor end signal is supplied from the home position sensor 32 to the CPU 2B. A rotation direction signal, a step angle signal, an on/off signal, and a drive pulse are supplied from the CPU 2B to the pulse motor driver 30.

An on/off signal is supplied to the lamp 34 from the CPU 2B. A pulse motor driver 30 controls a pulse motor 3B that moves the reading optical system. Pulse motor 36
moves the reading optics through the wire. lamp 34
is for illuminating the manuscript.

This entire embodiment is assumed to be controlled by a host system such as a personal computer, and the CPU'S is connected to the receiver 3.
8. Connected to a personal computer (not shown) via a driver 40. This connection complies with R3-422A. A start signal is sent from the personal computer, and 5LDRK and 5L control the amount of light emitted from the lamp.
The LGT signal is supplied to the CPU 2B via the receiver 38. A READY signal and an alarm signal for starting the operation are supplied from the CPU 2B to the personal computer via the driver 40.

An image bus 42 is connected to the DIPP 22, and the image bus 4
2 is connected to an all-pixel correction RAM 44. The all-pixel correction RAM 44 is for correcting high frequency distortion of read image information. A halftone processor 48 is also connected to the image bus 42 via a grayscale ROM 4B. The reading density of the density ROM4B is "normal", "dark", and "light".
The threshold values for switching to the three stages are memorized. The halftone processor 48 is a circuit that converts the read image information into a desired binary gradation or halftone signal. An example of the halftone processor 48 is MN8357 manufactured by Matsushita Electronics Industries, Ltd.

In this way, the image information read by the CCD line sensor 20 is subjected to various image processing by the DIPP 22 and the halftone processor 48, and then supplied to the personal computer via the driver 40 as image data RDDAT. Note that a synchronization signal and a clock pulse are also supplied from the halftone processor 48 to the personal computer via the driver 40.

The power supply unit 50 is a commercial power source AClooV to DC2.
It generates a power supply of 4V, DC15V, DC12VSDC5V (7). Here, 24V DC is connected to the pulse motor 3G and lamp 34, and 12V DC is connected to the cooling fan (
A) D, DC15VSDC5VJ (not shown) (applied to IC).

FIG. 3 is a block diagram of the DIPP 22. The distortion correction circuit 60 corrects distortions in the optical system of the CCD line sensor 20 and distortions due to variations in sensor characteristics. As shown in FIG. 4, one line of white data has two types of distortion: shading distortion and high frequency distortion.

In the former case, due to the unevenness of the light source and the characteristics of the lens, the amount of light decreases as it approaches both edges of the document, resulting in a white image.

This is a phenomenon in which the signal level gradually approaches the black level.

The latter is a phenomenon caused by variations in the characteristics of each pixel of the sensor and the influence of foreign matter (dust).

Shading distortion is corrected as follows.

Before reading a document, one line of white data is read from a white reflector inside the main body, and the shading waveform of this white data is detected and reproduced. A slice level for digitizing input image data is generated based on the reproduced shading waveform.

On the other hand, high frequency distortion is corrected as follows. This is done for all pixels. The process is the same as above until the shading waveform is played back before reading the original. Next, the difference between the input white data waveform and the shading waveform for one line is detected for each pixel, encoded, and stored in the all-pixel correction RAM 44. This difference is high frequency distortion.

The encoded data stored in the RAM 44 is called all-pixel correction data. All-pixel correction data is added to input image data to reproduce a waveform containing both shading distortion and high-frequency distortion. Using this waveform as a reference for the slice level,
Correct high frequency distortion.

The digitizing circuit 62 converts the analog voltage signal from the CCD line sensor 20 corresponding to the density of the document into digital image data of 4 bits per pixel (real halftone data of 16 gradations). Note that the digitizing circuit 62 also performs edge enhancement by equivalently differentiating the image signal. Equivalently means that an integrating circuit is connected between the shading waveform output terminal and the image signal output terminal, and the slice level is determined by the output of the integrating circuit, thereby generating a slice level that follows the input image signal. , the outline of the image signal can be emphasized.

The reduction/enlargement circuit 64 reduces/enlarges digitized data by converting the main scanning line density and sub-scanning line density of the read image. Main scanning line density conversion means reducing/enlarging data for one line. Sub-scanning line density conversion is a logical operation on the data of the line before the previous line, the previous line, and the current line.

FIG. 5 is a block diagram of halftone processor 48. Here, a 4-bit digital signal output from the DIPP 22 is supplied to a ranking calculation block 70 and an addition/redistribution processing block 72 as 8-bit image data ID77-0. The ranking calculation block 70 includes a ranking correction calculation block 74 and a dither matrix block 7.
B is connected. The dither matrix block 76 is used to represent pseudo halftones by dithering, and is connected to an external dither pattern RAM 7g. The output of the addition/redistribution processing block 72 is supplied to a binarization error calculation block 80. Output ODT of binarization error calculation block 80
is outputted to the outside via the driver 40 as image data RDAT. A line memory I/F block 82 is connected to the ranking correction calculation block 74, the ranking calculation block 70, and the addition/redistribution processing block 72. The line memory I/F block 82 has an external line memory 84 (
16 bits/pixel) are connected.

There are three modes in which the halftone processor 48 generates pseudo-halftone signals.
I mode, CAP I X2 mode, and dither mode can be selected. The CAPIX method is a peripheral pixel density accumulation/redistribution method, and its characteristics are that it reflects the binarization error in the next pixel's binarization judgment, and that it faithfully reproduces the local area density in the original image. It is to perform a redistribution operation on the

Therefore, the CAPIX method is superior to the dither method in terms of resolution and gradation. A redistribution operation is an operation in which the total sum of pixel data is set to 255 or 0 within a scanning window of 2 pixels x 2 pixels, and the data is allocated to each pixel.

The CAPIXI mode adds a weak periodic pattern to the additional data and outputs a dot-like output that is easy to see with the human eye, so it is used for inputting text, photographs, and line drawings. This is selected by the above-mentioned "photo mode 1".

The CAP I

The dither mode is selected by the above-mentioned "photo mode 3".

Note that when "character mode" is selected on the operation panel, the 4-bit halftone digital data obtained by the DIPP 22 is converted into 1-bit 2-bit digital data by the halftone processor 48.
It is converted to value data and output.

As explained above, according to this embodiment, halftone images such as photographs can be manually input to a computer as image data without reducing resolution or gradation, and line drawings can be used in a printing system that uses a computer to edit characters and images. Not only that, but also halftone images can be processed, expanding the range of applications.

Note that this invention is not limited to the embodiments described above, and can be modified in various ways.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to provide a human-powered image device that can read halftone images in a wide variety of gradations without reducing resolution.

[Brief explanation of drawings]

FIG. 1 is a perspective view of an embodiment of an image input device according to the present invention, FIG. 2 is a block diagram showing its circuit configuration, FIG. 3 is a block diagram of an image preprocessor in FIG. 2, and FIG. FIG. 5 is a signal waveform diagram showing the distortion included in the signal. FIG. 5 is a block diagram of the /X-Ftone processor in FIG. 2. 20... CCD line sensor, 22... Image preprocessor (DIPP), 24... Data bus, 2B.
...CPU. 34...Lamp, 3G...Pulse motor, 38...
・Receiver, 40...Driver, 42...Image bus, 44...All pixel correction RAM, 46...Nontan RO
M, 4g...halftone processor, 50...
Power supply unit.

Claims (1)

[Claims] means for reading grayscale information of a document and generating an analog image signal; means for correcting shading distortion and high frequency distortion of the analog image signal; and generating halftone image data from the corrected analog image signal by a dither method or a CAPIX method. An image input device comprising means for generating.