JPH0411446A - Picture reader - Google Patents

Abstract

PURPOSE:To attain masking processing with high accuracy by means of a simple circuit by applying masking with linear calculation of an analog signal. CONSTITUTION:An R-Y color difference signal (r-y1) from a buffer amplifier 31 is fed to an adder 35 and added with a Y signal y2 of a buffer amplifier 28 to obtain an analog signal r' subject to masking processing. An inverted R-Y color difference signal y1-r from an inverter amplifier 32 is given to an adder 36, in which the signal is added to a B-Y color difference signal (y1-b) and the result is fed to an adder 37, the result is added to a signal -y2 to obtain an analog G signal g' subject to masking processing. The B-Y color difference signal (b-y1) from a buffer amplifier 33 is fed to an adder 39, in which the signal is added to a Y signal y2 to obtain an analog signal b' subject to masking processing. Masking calculation with high accuracy is attained by applying analog linear calculation to the input analog signal.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an image reading device that outputs image data read by an image reading device as a video signal for display on a CRT (cathode ray tube) display device or the like. ! Regarding.

[Summary of the invention]

The present invention stores image data from an image reading means for reading an image original in an image memory, and sequentially reads the image data from the image memory at timings according to a predetermined television format, thereby generating a television video signal in the predetermined format. This is an image reading device that outputs images, and converts digital image data from the image memory into analog signals and performs masking processing using analog linear calculations, making it possible to perform highly accurate masking with a simple circuit configuration. There is.

[Conventional technology]

As conventional image reading devices, there are known scanner devices that output digital image data obtained by reading an image document using an image sensor such as a CCD through a digital interface such as 5C3I or R3232C1GPIB. In order to output this read image in the form of visual expression, especially to display it on a monitor, it is necessary to use a computer device, etc., which results in a large-scale system and requires time for signal processing. Therefore, responsiveness is relatively poor. For this reason, conventional image reading devices such as scanner devices are unsuitable for use in presentations at exhibitions, lectures, etc., for example.

Therefore, the present applicant reads an image original, stores it in an image memory, and repeats it from the image memory in synchronization with a horizontal scanning signal and a vertical scanning signal of a television signal of a predetermined format, for example, a so-called NTSC television signal. An image reading device that outputs a video signal for displaying a still image by reading the image is disclosed in, for example, the specifications of Japanese Patent Application No. 1-83330, Japanese Patent Application No. 1-83696, and Japanese Patent Application No. 1-83697. This is proposed in drawings, etc. According to such an image reading device, an original image can be visualized and displayed with good responsiveness in a short time.

[Problem to be solved by the invention]

By the way, when a color document is read by the image reading device and displayed in color on a monitor device, etc.,
In order to improve the accuracy of color reproducibility in the television video signal that is finally output, color correction (color correction) processing, so-called masking processing, is performed. This refers to the three primary colors read out from the image memory, such as R (red), G (green),
For each image data r, g, b of B (blue), as each data r', g', b' after masking processing, r'=
αrr+β1g γrb g""α, r+βq g 1T 9 bb'=α, r+βbg+rbb This is determined by performing the calculation as shown in (1). α1 in this equation (1). β
r, rr+α9. ... are coefficients for masking calculation.

Performing such calculations for each pixel requires a high degree of computing power (especially high speed) from the CPU, so R, G, B
A ROM table or the like is usually used that inputs each data r, g, b and outputs calculated data r, g', b'' of the above equation (1).

However, if the R, G, and B data r, g, and b are each 8 bits, and the output data r'' and gb'' are each 8 bits, then for example, each of the 8 bits of data r, g, and b is input. RO for outputting bit data r°
The capacity of M table is 8x2"x2@x2" [focus] = 16M hide, and R of the same capacity is required for data g and b".
Since OM is required, the memory capacity becomes too large and costs increase. Here, for example, in order to output the above-mentioned data r', two of the three manual data, for example, data r and g, are used to form 8-bit/byte intermediate data dr9, and the remaining input data b and Final output data r' is obtained using this intermediate data drg.

In this case, the capacity of each ROM table for obtaining intermediate data d rg and final output data r is 8X2"X2" (focus) = 64, so the total capacity is 128. Memory capacity is sufficient.

However, the memory capacity is still large and the data
Since memory of the same capacity is required for ' and b'', it not only increases cost, but also has the disadvantage of poor accuracy because it is a simple method.

Furthermore, since the masking processing by these methods is performed digitally, there is also the drawback that quantization errors become large at the stage of rounding the output to 8 bits, making it difficult to maintain hardness.

The present invention has been made in view of these points, and it is an object of the present invention to provide an image reading device that can perform masking processing with high accuracy using a simple and inexpensive circuit.

[Means to solve the problem]

An image reading device according to the present invention includes a color image reading means for reading a color image original, a means for converting an output signal from the color image reading means into digital image data, and an image memory for storing the digital image data. means for sequentially reading the digital image data stored in the image memory at timings according to a predetermined television video signal format; means for converting the digital image data read from the image memory into an analog signal; The above-mentioned problem is solved by comprising a masking processing circuit that performs masking processing by linear calculation of signals, and an output section that outputs the masked signal as a television video signal in the above-described predetermined format. .

[Operation] Since masking is performed by linear calculation of analog signals, masking processing can be performed accurately with a simple circuit configuration.

(Embodiment) First, FIG. 1 is a block circuit diagram showing the basic configuration of essential parts of an embodiment of an image reading apparatus according to the present invention.

In the main part configuration of the image reading device shown in FIG. 1, the image memory 100 stores R(
Digital image data for each color (red), G (green), and B (blue) is stored.

The digital image data of each color of R, G, and B stored in this image memory is read out by the memory read control circuit B110 in a predetermined television video signal format (for example, NTSC).
The signals are read out in parallel at timings according to the horizontal (H) synchronization signal and vertical (V) synchronization signal specified in the standard format.

The digital image data of each color of R, G, and B read out from this image memory 100 is sent to a D/A converter 101.10.
2.103, each is converted into an analog signal. These analog R, G, and B signals are represented by r, g, and b, respectively. An analog masking processing circuit is provided to perform masking processing by linear calculation of these analog signals r, g, and b. That is, the analog R signal r is sent to a unit gain buffer amplifier 104 and an inverter amplifier 105, the analog G signal g is sent to a unit gain buffer amplifier 106 and an inverter amplifier 107, and the analog B signal is sent to a unit gain buffer amplifier 106 and an inverter amplifier 107. 10
8 and an inverter amplifier 109, and these are added and mixed at a predetermined ratio by resistors 121 to 129, thereby producing r', g', b as masked R, G, and B signals. ' is now available.

In the specific circuit of FIG. 1, the resistors 121.122
．． The signal addition ratio based on each resistance value of 123 is α1.
, rr, rr, and the signal addition ratios based on the resistance values of the resistors 124, 125, and 126 are α9, β4, γ, respectively.
When the signal addition ratios based on the resistance values of resistors 127 and J28.129 are α5, β5, and γ, respectively, r'=(r, r-βrg 'rtb g'=-α, r+β*g' rob b'=-crbr-βbg+rbb,-(2).Here, if α1, β9, and γ are all 1, then r'=r-(βrg+γ,b) g'=g- (α, r+γwb) b'-b-(α, r+βbg) ...(3) It can be simplified as (3).The coefficient β1.γ1...β in this formula (3)
, are values of about 0.1 to 0.2 or less. The R, G, , B signals r', g", b calculated by analog linear calculation of resistance addition to satisfy such a formula are respectively connected to the amplifier 131.1.
32.133, output terminal 141.142.14
It is designed to be taken out from 3.

According to an image reading device having such a configuration,
Since masking processing for color correction or color correction is performed by analog linear calculation using resistance addition of analog signals, masking calculation with higher accuracy than digital calculation can be realized with a relatively simple circuit configuration. In other words, close-up 1) R during digital masking processing
No OM square is required, calculation errors due to quantization errors when rounding the output to predetermined bits (for example, 8 bits) are eliminated, calculation accuracy can be increased, and signal processing resolution (quantization level) can be easily expanded.

Next, the overall schematic configuration of an image signal reading device according to another embodiment of the present invention will be described with reference to FIG.

In FIG. 2, an image reading gutter 2 for reading an image original GD placed on an original placing table l includes a light source 3.
, a multi-lens array 4 and a CCD line sensor LS are provided so that the light source 3 illuminates the image original GD and the reflected light from the image original GD is received by the line sensor LS via the multi-lens array 4. It has become.

This line sensor LS has, for example, 1'728 CCs.
D light-receiving cells are arranged in a straight line along the main scanning direction, and for example, when reading one line in the main scanning direction (vertical direction on the display screen) from an image original CD, the light source 2 By sequentially emitting light corresponding to the three primary colors RlG and B, image signals of the three primary colors can be obtained line sequentially (in this case, the lines are in the vertical direction of the screen). . Image reading head 2
The output from the line sensor LS is amplified by the amplifier 5,
The signals are sent to the A/D converter 6 and converted into digital image data of, for example, 8 bits per pixel, one line at a time, in the order of R, G, and B signals.

This digital image data is processed by the shading correction circuit 7.
The non-uniformities in the gradation expression characteristics due to causes such as non-uniformity in the amount of light #3 and non-uniformity in the sensitivity of the line sensor LS are corrected. The output from the shading correction circuit 7 is M
The signal is sent to the TF correction circuit 8 and subjected to MTF correction, that is, contour enhancement correction. The output from the MTF correction circuit 8 is output after timing adjustment is performed by a data buffer 9 such as a so-called FIFO, and is stored in an image memory 10. Here, digital image data obtained from the line sensor LS via the amplifier 5 and A/D converter 6 is sent to the light amount detection circuit 11, so that
The amount of light from the light source 3 is detected and supplied to the system control circuit 12, and the system control circuit 12
Based on this light detection signal, the light source drive circuit 13 is controlled so that the light source 3 has an appropriate amount of light. The system control circuit 12 also controls a line sensor drive circuit 14, a motor drive circuit 15, etc., and the line sensor drive circuit 14 reads and drives the line sensor LS in the gutter 2 to read the image, and controls the motor drive circuit. Reference numeral 15 rotates a motor 6 that moves the gutter 2 in the sub-scanning direction for image reading.

Next, digital image data r for each color of R, G, and B
. That is, at the time of writing, since the light-receiving cell arrangement direction (main scanning direction) of the line sensor LS is the vertical direction of the screen, the line sensor LS is moved in the horizontal direction (sub-scanning direction) for each vertical line. (
Each line of R, G, and B is sequentially written in accordance with the scan). When reading from the image memory frame, the memory control circuit 18 performs horizontal direction control at a timing corresponding to a horizontal (H) synchronization signal and a vertical (V) synchronization signal of a predetermined television signal format (for example, NTSC format). By performing address access that moves in the vertical direction while repeating line scanning of
, B's digital image data r, g, b are read out in parallel and output.

The R, G, and B digital image data r, g, and b read out from the image memory 10 are converted into analog signals (also shown as r, g, and b) by the D and /A converters 19, respectively. , two types of luminance (Y) signals y via the buffer 20
They are sent to resistance matrix circuits 21 and 22 for forming I and y2, respectively. The luminance signal y1 from the resistance matrix circuit 21 has its polarity inverted by the inverter amplifier 23 to become -yI, and is sent to the adders 24 and 25.

The adder 24 is supplied with the analog R image signal r from the buffer 20 via a unit gain buffer amplifier 26, and from this adder 24 is supplied an R-Y color difference signal (ry).
+) is obtained. This RY color difference signal (ry+) is passed through a low pass filter (LPF) 41 to a color adjustment circuit 3.
0. Further, the analog B image signal from the buffer 20 is supplied to the adder 25 via a unit gain buffer amplifier 27;
A BY color difference signal (bye) is obtained. This B-
The Y color difference signal (bye) is supplied to the color adjustment circuit 30 via the LPF 42. In addition, the luminance signal y2 from the resistance matrix circuit 22 is transmitted through the buffer amplifier 28 of unity gain and through the delay circuit 43 such as a delay line having a delay time equal to the signal delay time in each of the LPFs 41 and 42. The signal is sent to the color adjustment circuit 30. This color adjustment circuit 30 receives these color difference signals (ry
+), (b-yl) and the luminance signal y2, r r+yz 31 g'=211(r+b+yz) b'=b+y2-yl 0. - Masking processing is performed by forming R, G, and B signals r", g", and bo as shown in (4).

Here, only the portion related to this masking process is extracted and shown in FIG.

In FIG. 3, the resistance matrix circuit 21 divides the input R, G, and B color signals r, g, and b into a predetermined ratio α.
By adding the resistances at the ratio of 1, β1, and T1, the above Y
The resistance matrix circuit 22 generates the Y (luminance) signal y2 by adding the resistances of each color signal r, g, b at a predetermined ratio α2, β2, T2.
is formed. That is, y, = αlr + β + g + r Ibyt - α2r + βzg + rzb (5). Here, the normal luminance signal y in the NTSC system
is approximately y = 0.3 Or + 0.59 g + 0.11 b
--- (6) However, each of the above resistance matrix circuits 2
1.22, for example, α,=0.1. β,=0.9. γl−0α2=
0.1+ βz=0.8+ rz=0.8−・−(7
) is selected.

Each of the circuits 23 to 28 in FIG. 3 corresponds to each part with the same reference numeral in FIG. 1, and a description thereof will be omitted.

The R-Y color difference signal (rV+) from the adder 24 is sent to the unit gain buffer amplifier 31 and inverter amplifier 32 of the color adjustment circuit 30, and the B-
The Y color difference signal (b yl) is sent to the unit gain buffer amplifier 33 and inverter amplifier 34 of the color adjustment circuit 30.
is being sent to. The R-Y color difference signal (r yl) from the buffer amplifier 31 is sent to the adder 35, and is added to the Y (luminance) signal y2 from the buffer amplifier 28, resulting in the signal as shown in equation (4) above. The masked analog R signal r' (=r+Yz Y1') is obtained.

Next, the polarity of R- from the inverter amplifier 32 is inverted.
The adder 36 converts the Y color difference signal (yl r) into a B-Y color difference signal (y
l b) is added to (2y+ r b)
The output from the adder 36 is sent to the adder 37 and added to the signal -y2 obtained by inverting the polarity of the output from the buffer amplifier 28 with the inverter amplifier 38, thereby achieving the above (4). As shown in Figure 2, the masked analog G signal g゛, that is, 2 yl-(
r+b+yz) is obtained. Furthermore, the B-Y color difference signal (byl) from the 1 nopha amplifier 33 is sent to the adder 3
9 and buffer amplifier 2o X et al. Y (luminance)
By being added to the signal y2, the masked analog B signal b'' (=b+
yz y+).

This allows masking processing (color correction, color correction processing)
can be performed by analog linear calculation using resistance addition of input analog signals at a predetermined ratio, and with a relatively simple circuit configuration, masking calculation with higher precision than digital calculation can be realized.

By the way, in the specific embodiment shown in FIG. 2, the configuration for masking processing as shown in FIG.
LPF41 for removing so-called false color phenomenon.
42 is combined with the band limit configuration. In other words, L is used only for the color difference signals from each adder 24.25.
Bandwidth limiting processing using PF41.42 is performed to lower the resolution, and the luminance signal is simply delayed and sent (without passing through the LPF), so even if the color resolution is lowered, it is not possible to suppress resolution degradation of the luminance component. can. This is because the R, G, and B light sources are turned on sequentially without moving the line sensor to read a color image in line order.
When each reading position of B is shifted, so-called false color occurs when reading a fine striped pattern in a color original, by using the configuration of the embodiment of the present invention, deterioration of resolution can be suppressed. However, it is possible to remove false colors.

Next, the R, G, B signals (r'
, g', b') are R, G, B line drivers (
R, G, B signal output terminals 51 .
52 and 53 respectively. Further, the R, G, and B signals from the color adjustment circuit 30 are added and combined at a predetermined ratio by the resistance matrix circuit 60 to become a luminance (Y) signal. This Y signal has its polarity inverted by an inverter amplifier 61 and is sent to adders 62 and 63, respectively.
The adder 62 receives the R signal (r
The Y signal is subtracted from
The Y signal is subtracted from the B-Y color difference signal. The R-Y color difference signal from the adder 62 is sent to the modulator 66, and the BYY color difference signal from the adder 63 is sent to the BYY color difference signal modulator 67, so that the subcarrier of phase 90' from the subcarrier generation circuit 68 becomes R. In the -Y color difference signal, the subcarriers with a phase of 0° are each balanced-modulated with the B-Y color difference signal. By mixing these modulated output signals in an adder 69, a carrier color signal, a so-called chroma (C) signal, whose subcarriers are quadrature-phase modulated (orthogonal double modulation) with each color difference signal is obtained. This C signal is sent to a narrow band BPF (band pass filter) 71 and a wide band BPF 81, respectively.

The BPF71 is a narrow band filter that has a passband of, for example, about 1 MHz and limits the signal component to 0.5 M& or less in order to form a C (chroma) signal component of a composite color video signal. be. That is, the Y (luminance) signal from the resistance matrix circuit 60 is sent to the adder 75 via the delay circuits 73 and 74, and the BPF 7
1 to form a composite color video signal, and this composite color video signal is taken out from an output terminal 77 via a driver amplifier 76. Here, the delay times of the delay circuits 73 and 74 are set according to the group delay amount of the BPF 71. On the other hand, the BPF 81 is provided for outputting the C signal when separating and extracting the Y signal and the C signal, and the pass band is, for example, about 3M)[z or more, and the signal component is at least It is a wideband filter that allows 1.5 MHz to pass through four times. The output from this BPF81 is
It is designed to be taken out from the output terminal 83 via the driver amplifier 82, and the Y signal that forms a pair with this is taken out from the output terminal 85 from the delay circuit 73 via the drive amplifier 84. That is, BPF81
Since the amount of group delay is small, the Y signal is taken out from the delay circuit 73 with a delay time corresponding to this.

In this way, the C signal component of the composite color video signal is band limited by the narrow band BPF 71 and added to the Y signal, but the C signal component in the case of Y/C separated output is added to the Y signal via the wide band BPF 81. Since the Y-signal delay portion (delay circuit 73) is taken out, it is possible to reduce color smudges (color stains) in the monitored image, and to reduce the amount of delay in the BPF 810 group, improving waveform transmission characteristics in the Y signal delay portion (delay circuit 73). , the band and waveform distortion characteristics of the Y signal are improved.

〔Effect of the invention〕

As is clear from the above description, the image reading device according to the present invention converts digital image data read from the image memory into an analog signal, and performs masking processing by linear calculation of the analog signal. Therefore, there is no need for a large-capacity ROM table, etc., and a masking calculation with higher precision than digital calculation can be easily realized with a relatively simple circuit configuration. Specifically, masking eliminates calculation errors during digital calculation processing, increases calculation precision, and improves signal processing resolution (quantization level).
can be easily expanded.

[Brief explanation of the drawing]

Part 1 is a block diagram showing the main parts of one embodiment of the image reading device according to the present invention, FIG. 2 is a block circuit diagram schematically showing another embodiment of the image reading device according to the invention, and Part 3 The figure is a block circuit diagram showing a specific configuration of the main parts of the embodiment. LS...Line sensor CD...Image original 1...Original table 2......To read the image, Drop...
... A/D converter 10 ... Image memory 12 ... System control circuit 18 ...
...Memory control circuit 19...D/A converter 21.22.60...Resistance matrix 23.6
100619. Inverter amplifier 24.25.62.6
3.69.75...5. Adder 30...Color adjustment circuit

Claims (1)

[Scope of Claims] Color image reading means for reading a color image original, means for converting an output signal from the color image reading means into digital image data, an image memory for storing this digital image data, and this image memory. means for sequentially reading digital image data stored in the image memory at timings according to a predetermined television video signal format; means for converting the digital image data read from the image memory into an analog signal; An image reading device comprising: a masking processing circuit that performs masking processing by calculation; and an output section that outputs the masked signal as a television video signal in the predetermined format.