JPH08139954A - Image reader - Google Patents

Abstract

PURPOSE: To reduce transfer time by reducing transfer data quantity. CONSTITUTION: An RGB signal by one line received by a color line CCD 1 is given via a masking processing section 2 and a multiplexer 3 to an A/D converter 4, in which the signal is converted into digital data and written in a register 5. The RGB data from the register 5 are given to a luminance/color difference conversion section 6, in which the data are converted into a luminance signal Y and color difference signals (r-Y),(b-Y). Then a gamma processing section 7 applies gamma correction to the luminance signal Y and color difference signals (r-Y),(b-Y) to obtain output data. The quantity of the output data is reduced to 2/3 or below than the RGB data, then the transfer time is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image reading apparatus for reading a document or film on which characters and pictures are drawn line by line.

[0002]

2. Description of the Related Art Recently, it has been proposed to print an image by reading a document or film on which characters and pictures are drawn with an image reading device (scanner) and sending the read data to a printer. An example of this is shown in FIG.
In this example, the original data read by the scanner is sent to a printer connected via a cable and printed. As shown in the figure, the scanner main body 40 and the color printer main body 60 are connected via a cable 50, the scanner main body 40 is positioned on the original, and the push button switch 56 is operated to operate the original from the window 58. Scanner body 4 while observing
By manually moving 0, the image on the document is read line by line along with the character information. The read data is sent to the color printer main body 60 via the cable 50 as the R, G, and B primary color signals, and the image and character information is printed on the paper based on the signal sent by the printer main body 60. It

A memory switch 63 provided in the color printer body 60 is a switch for storing one frame of image data from a video input terminal in a frame memory, and a print switch 64 starts printing. It is a switch that is sometimes operated. Also, 62
Is an openable / closable tray for receiving printed print paper, 65 is an operation panel, 66 is a paper tray for storing print paper, 67 is an input terminal section, and 67C is a scanner input terminal.

As described above, the scanner is a color handy scanner, and the internal structure seen from the upper surface is shown in FIG. 6 (a).
FIG. 6B shows the internal structure viewed from the side. In FIGS. 6A and 6B, the light emitted from the fluorescent lamp 46 irradiates the portion of the document located at the reading position, the reflected light from the document is reflected by the mirror 43, and converged by the lens 44. An image is formed on the color CCD 45. Therefore, by scanning the color CCD 45, R, G, B data for one line can be obtained. The scanner body 40 includes rollers 41A and 4A.
It is configured to be movable on the platen by 1B,
When the scanner body 40 moves, the gear 47 fixed to the shaft of the roller 41B rotates together with the roller 41B, so that the encoder 48 connected to the gear 47 also rotates. The rotation of the encoder 48 is detected by the photo interrupter 42, and a pulse signal corresponding to the rotation of the encoder 48 is output.

Since the roller 41B is adapted to rotate according to the moving distance of the scanner body 40, the number of pulses output from the photo interrupter 42 depends on the moving distance. That is, by moving the scanner body 40 and outputting the data from the color CCD 45 in synchronization with the timing signal generated from this pulse signal, RGB data obtained by scanning the original line by line can be obtained. If the original is translucent (film)
In place of the fluorescent lamp 46, a light source is provided on the back surface of the document table.

Next, FIG. 7 is a circuit block diagram of a scanner for processing an image signal output from the color CCD 45, in which 51 is a scanner controller (CPU), 52 is a masking processing circuit, and 53 is a parallel RGB signal serial. A multiplexer for RGB signals, 54 a gamma correction circuit, and 55 an analog / digital (A / D) converter. Here, when the push button 56 is operated, the entire circuit is activated, and a signal for one line of the object imaged on the color CCD 45 is input to the masking circuit 52.
The masking circuit 52 uses each RG as shown in the following formula 1.
It is composed of a sum-of-products circuit that performs a matrix operation of predetermined coefficients (M00 to M22) on the B signal, and improves color reproducibility.

[Equation 1]

The masking-corrected parallel color signals Rout, Gout, and Bout are analog multiplexer 53.
Are switched to obtain serial RGB signals, and then the gamma correction circuit 54 performs gradation correction. In this gamma correction, the gamma correction of the video signal to the 0.45th power is performed, so that the other signals input to the color printer, that is, the signals captured by the scanner in this case are also 0.
By performing 45th power gamma correction, the signal processing circuit of the printer is made common.

Output level of multiplexer 53 and A /
The conversion clock of the D converter 55 is the scanner controller 5
The digital data of R, G, and B, which are formed by 1, are also output in synchronization with the write reset signal and the write clock signal output from the scanner controller 51. Note that the gamma correction may be performed after conversion into a digital signal. In this case, 10 bits of A /
If D conversion is performed, gamma correction is performed, and then 8-bit data is output, a good result with a small calculation error can be obtained.

The synchronization information (encoder signal) from the encoder 42 of the scanner is input to the scanner controller 51, and digital data is output line by line in synchronization with this, but if the scanner main body 40 moves. When the pulse interval of the encoder is too short, the LED 57 is turned on from the scanner controller 51 to warn the user.

[0010]

However, in the above-described color handy scanner, the data of the three primary colors R, G, B are output from the scanner for each pixel, and therefore the number of data is necessary for printing. There is a problem that the number of data is larger than that of the data and it takes a long time to transfer to the color video printer. In addition, if the color handy scanner is used as an input device to a color video printer for processing luminance / color difference data, the printer side will be RG
There is a problem that a circuit for converting B data into luminance / color difference data is required. Furthermore, when the data of the three primary colors of R, G, and B are output for each pixel, the number of data increases when the resolution is improved, and more data than the number of valid printable data is transferred to the printer side. However, redundant processing time is required, which hinders the improvement of system efficiency.

Therefore, it is an object of the present invention to provide an image reading apparatus capable of shortening the data transfer time to a color printer and transferring only valid printable data to the color printer.

[0012]

In order to achieve the above object, an image reading apparatus of the present invention reads an original document line by line and outputs R, G, B three primary color signals corresponding to the read original document. The color line CCD and the R, G, B three primary color signals output from the color line CCD are input, and the R, G, B three primary color signals are converted into a luminance signal and a color difference signal and output as output data. An output luminance / color difference conversion means is provided.

In the image reading device, the R, G, B three primary color signals output from the color line CCD are output for each pixel of R, G, B, and the luminance / color difference conversion means is By calculating the R, G, B signals for each pixel for each color, the color data of r, g, b is obtained, and the luminance signal is created using the obtained color data of r, g, b. Further, the arithmetic processing for each color of R, G, B is made different according to the normal mode or the expansion mode.

[0014]

According to the present invention, when used as an input device to a color printer for luminance / color difference data processing, the amount of data to be transferred when transferring luminance / color difference data is smaller than that when transferring RGB data to the printer. Since it can be reduced, the transfer time can be shortened. Further, the printer side does not need a circuit for converting RGB data into luminance / color difference data. Furthermore, when transferring luminance / color difference data, the number of transfer data does not change according to the resolution, and only valid printable data can be transferred, so that the redundancy of transfer time can be improved.

[0015]

1 is a block diagram of a color handy scanner to which an image reading apparatus of the present invention is applied. In this figure, reference numeral 1 denotes a color line CCD that reads an image of a document for one line and outputs an RGB analog signal for each pixel by forming an image of the document on the CCD for one line.
Is a masking processing unit for performing an analog operation for improving the color reproducibility of an RGB analog signal, 3 is a multiplexer for rearranging parallel RGB analog signals in time series into a serial RGB analog signal, and 4 is an RGB digital signal for RGB analog signal An analog / digital (A / D) converter for converting into a signal, 5 is a register for temporarily storing an RGB digital signal for each of R, G, B data, and 6 is for each of R, G, B stored in the register 5. The digital signal is processed to obtain luminance data (Y) and color difference data (r-
Y), (b-Y), a luminance / color difference conversion unit, and 7 is a gamma processing unit that performs 0.45 power gamma correction, for example.

Further, 8 generates a timing signal from the received encoder signal, and the multiplexer 3
A scanner controller that controls the A / D converter 4 and the register 5, a photo interrupter 9 that detects the rotation of the encoder 10 and outputs an encoder signal, 10 is an encoder that rotates as the scanner moves, and 11 is operated. A switch button 12 starts the operation of the scanner by the operation, and 12 is an LED for displaying a warning that the moving speed of the scanner is too fast.

The main structure of the color handy scanner thus constructed is as shown in FIG. Therefore, the operation of the color handy scanner according to the present invention will be described with reference to FIGS. When the switch button 11 is operated, the entire color handy scanner is activated, and the light emitted from the fluorescent lamp 46 illuminates the portion of the document located at the reading position. Then, the reflected light from the original document is reflected by the mirror 43 and converged by the lens 44 so that the color C
An image is formed on the CD 45. The color CCD 45 is shown as the color line CCD 1 in FIG.
By scanning the color line CCD 1, RGB analog signals for one line can be obtained.

The scanner body 40 includes rollers 41A,
41B is configured to be movable in the direction perpendicular to the reading line on the platen, and when the scanner body 40 moves, the gear 47 fixed to the shaft of the roller 41B rotates together with the roller 41B. The encoder 48 connected to 47 comes to rotate. The rotation (deviation) of the disk-shaped encoder 48 is detected by the photo interrupter 42 and a pulse signal is generated.
This pulse signal is sent to the scanner controller 8 as an encoder signal, and a timing signal is generated based on the encoder signal.

Since the roller 41B rotates in accordance with the moving distance of the scanner body 40, the photo interrupter 4
The number of pulses output from 2 depends on the moving distance. That is, by moving the scanner body 40 and generating image data converted into luminance / color difference data in synchronization with a timing signal generated by the scanner controller 8 with the timing of the pulse signal as a reference, the document is read. Output data composed of luminance data and color difference data scanned line by line can be output from the color handy scanner.

By the way, the RGB analog signal for each pixel output from the color line CCD 1 is subjected to matrix calculation of a predetermined coefficient (M00 to M22) with respect to each RGB analog signal in the masking processing section 2, and the above-mentioned equation 1 is used. Analog calculation is performed to improve color reproducibility. further,
The RGB analog signals from the masking processing unit 2 are paralleled by the multiplexer 3 to R, G, B.
The analog signals are sequentially switched by the timing signal from the scanner controller 8 to become serial RGB analog signals.

The serial RGB signal is
The A / D converter 4 converts the RGB digital data into digital RGB signals at the timing supplied from the scanner controller 8, and the converted RGB digital data has a register 5-1 for storing R data and a register 5-2 for storing G data. , B data are stored in the register 5-3 for storing the B data, respectively, by the timing signal from the scanner controller 8.

The RGB digital data stored in these registers 5-1 to 5-3 is input to the luminance / color difference conversion unit 6, and the luminance data Y and the color difference data (r-Y), (b
-Y). The converted luminance data Y and color difference data (r−Y) and (b−Y) are subjected to gradation correction by the gamma processing unit 7. In this gamma correction, a gamma correction of 0.45 to the video signal input to the color printer is performed, so that the other signal input to the color printer, that is, the signal captured by the color handy scanner in this case is 0. The signal processing circuit of the printer can be standardized by performing the gamma correction of 0.45 power. The gamma correction performed by the gamma processing unit 7 may be performed before conversion into a digital signal.

As described above, the pulse signal (encoder signal) from the photo interrupter 9 is input to the scanner controller 8 and in synchronization with this, digital luminance / color difference data is output line by line. If the main body of the color handy scanner moves too fast and normal data cannot be obtained by scanning the original line by line from the color handy scanner, it means that the pulse interval from the photo interrupter 9 is too short. LED is detected by the scanner controller 8
A warning is given to the user by turning on.

When the original is translucent (film)
In place of the fluorescent lamp 46, a light source is provided on the back surface of the document table. In this embodiment, the system in which the scanner itself is moved with respect to the original paper is shown, but the scanner may be driven by a motor. Further, in the image capturing scanner for a computer, the shape of the pixel is a square. However, by changing the composition ratio of the coupling gear of the roller and the encoder, it is possible to obtain data such that the pixel becomes a vertically long pixel. (When a video signal is sampled at 4f _SC , it becomes a vertically long pixel, so the data from the scanner is also adjusted to that).

Next, an example of the pixel array of the color line CCD 1 is shown in FIG. 2, where the green pixels are 2048 G ₀ , G ₁ , G ₂ , ... G ₂₀₄₆ , G arranged in a horizontal row.
₂₀₄₇ , red pixels are arranged in horizontal rows one by one, and 1024 pieces of R ₀ , R ₁ , R ₂ , ... R ₁₀₂₃ are arranged, and blue pixels alternate with red pixels in horizontal row. 1024 B ₀ , B ₁ , B ₂ , ... B arranged in
_{It consists of 1023} .

By the way, FIG. 3 shows a data conversion formula for generating the luminance data Y and the color difference data (r-Y), (b-Y) from the RGB signal from the color line CCD 1 thus constructed. In the figure, in the normal mode, the data of red r _n is obtained by performing the operation of (R _2n + 2R _{(2n + 1)} + R _{(2n + 2)} ) / 4.
_4n + G _{(4 n + 1)} + G _{(4n + 2)} + G _{(4n + 3)} ) / 4 is calculated to obtain the data of green g _n (B
_2n + B _{(2n + 1)} ) / 2 is calculated to obtain blue b _n
To get the data of. However, n is an integer of 0-511. Then, 0.3r _n + 0.59g _n +0.
So as to obtain a luminance signal Y _n by performing the calculation of 11b _n, and calculates the color difference signal _{(r n -Y n), (} b n -Y n).

In the double magnification mode, (R _n + R
_{(n + 1)} ) / 2 is calculated to obtain data of red r _n , and (G _2n + G _{(2n + 1)} ) / 2 is calculated to obtain data of green g _n. And then B
_{Let n be} the data of blue b _n as it is. And 0.
3r _n + 0.59g _n + 0.11b _n is calculated to obtain the luminance signal Y _n , and (r _n −Y
_n), are computed color difference signal (b _n -Y _n).

Further, in the 4 × magnification mode, when n is an even number, the data of R _{n / 2} is red r _n data, and when n is an odd number, the data of R _{(n-1) / 2} is red r n. _n data, G _n as green g _n data as it is, and when n is an even number, B _{n / 2} data as blue b _n data, n
When is odd, the data of B _{(n-1) / 2} is used as the data of blue b _n . And 0.3r _n + 0.59g _n +0.11
so as to obtain a luminance signal Y _n by performing the calculation of b _n, and calculates the color difference signal _{(r n -Y n), (} b n -Y n).

As described above, the conversion formula is made different according to each mode, but the luminance data Y is 1 regardless of the mode.
There are 512 pieces of data from Y _{0 to} Y ₅₁₁ per line,
Since the color difference data (r-Y) and (b-Y) are 256 data items per line, the data amount becomes constant even if the mode is changed and the resolution is changed, and the printer is connected to the color handy scanner. In this case, only the number of printable data is sent to the printer side. That is, the number of transfer data per line becomes 1024,
Compared with 512 × 3 = 1536 pieces of data in the case of RGB data, the number of pieces of data is reduced to ⅔, and the transfer time can be shortened. Further, the number of color difference data may be further reduced depending on the data processing method of the printer.

Then, not only the luminance / color difference data but also the light reset and the data clock are output from the color handy scanner and transferred to the printer.
This light reset is a signal that resets the memory on the printer side to the initial state before transferring the luminance / color difference data, and the data clock is a clock synchronized with the transferred luminance / color difference data. This state is shown in FIG. 4. It is understood that the output data of the luminance / color difference data shown in FIG. 4A is synchronized with the falling edge of the data clock shown in FIG. In the printer, the transferred brightness /
The output data of the color difference data is written in the memory.

In the above description, the case where the color handy scanner manually performs the sub-scanning operation has been described.
When driving the color handy scanner with a motor, etc.,
The roller 41B shown in FIG. 6 may be rotated by a motor. Further, the image reading apparatus of the present invention is not limited to a handy scanner, but may be of a type in which an original is fed by a motor or the like, or the original may be placed on a transparent plate with the transparent plate facing the reading part on the back side of the transparent plate. May move. In addition, as shown in FIG.
The reading position illuminates the reading position from above. However, when reading a transparent original such as a film, the fluorescent lamp 46 is turned off and the transparent original placed on the light box is read. Good.

[0032]

Since the present invention is configured as described above, when it is used as an input device to a color printer for luminance / color difference data processing, the amount of transfer data is larger than that when transferring RGB data to the printer. Can be reduced,
The transfer time can be shortened. Further, the printer side does not need a circuit for converting RGB data into luminance / color difference data. Furthermore, when transferring luminance / color difference data, the number of transfer data does not change according to the resolution, and only valid printable data can be transferred, so that the redundancy of transfer time can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram of a color handy scanner to which an image reading device of the present invention is applied.

FIG. 2 is a diagram showing an example of a color line CCD pixel array.

FIG. 3 is a table showing a luminance / color difference data conversion formula in each mode.

FIG. 4 is a timing chart showing a data output timing chart.

FIG. 5 is a diagram showing a state in which a printer is connected to the handy scanner.

FIG. 6 is a diagram showing a main structure of a handy scanner.

FIG. 7 is a circuit block diagram of a conventional handy scanner.

[Explanation of symbols]

 1 Color line CCD 2 Masking circuit 3 Multiplexer 4 A / D converter 5 Register 6 Luminance / color difference conversion unit 7 Gamma processing unit 8 Scanner controller 9 Photo interrupter 10 Encoder 11 Switch button 12 LED 43 Mirror 46 Fluorescent lamp 41A, 41B Roller

Claims (3)

[Claims] 1. A color line CCD for reading an original document line by line and outputting three primary color signals of R, G, B according to the read original document, and R, G, B output from the color line CCD. An image reading apparatus comprising: a luminance / color difference conversion unit that receives three primary color signals, converts the three primary color signals of R, G, and B into a luminance signal and a color difference signal and outputs as output data. 2. An R output from a color line CCD,
The G, B three primary color signals are output for each pixel of R, G, B, and the luminance / color difference conversion means is for each pixel of R, G, B.
The color signal of r, g, b is calculated by processing the B signal for each color, and a luminance signal is created using the calculated color data of r, g, b. Image reading device. 3. The image reading apparatus according to claim 2, wherein the arithmetic processing for each color of R, G, and B is different depending on the normal mode or the enlargement mode.