JPH01108867A - Masking processing circuit - Google Patents

Abstract

PURPOSE:To reduce the scale of circuits by storing plural ink quantity data relating to a specific color corresponding to color density obtained by converting light intensity represented respectively by plural color signals on a conversion table. CONSTITUTION:When plural color signals representing respectively the intensity of the light of plural wavelengths are supplied to conversion tables 30-32 in a masking processing circuit 29, since the ink quantity data corresponding respectively to the intensity of a series of light is stored in the conversion tables 30-32, the conversion tables 30-32 output plural ink quantity data representing respectively the ink quantity data corresponding to the intensity of the specific light represented by plural color signals to be supplied. The plural ink quantity data signals represent the ink quantity data corresponding to the color density subjected to color density conversion from the light intensity represented by each color signal, it is not required to apply color density conversion in advance by a logarithmic conversion circuit as a conventional circuit and the color signal is supplied directly to the conversion tables 30-32. Thus, the circuit scale is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a masking processing circuit, and more specifically, in a digital color copying machine or the like, color signals representing the intensities of red light, green light, and blue light, respectively, are processed into cyan and magenta. , and relates to a masking processing circuit that converts into signals representing ink amounts of each color of yellow.

[Prior Art] As a conventional color image reading device equipped with this type of masking processing circuit, for example, the one shown in FIG. 2 is known. In FIG. 2, 1 is a document on which a color image is drawn, and this document 1 is irradiated with white light from a light source 4 that receives driving force from a motor 2 and moves in the direction of arrow 3, and the reflected light is An image sensor 5 composed of a plurality of CCD elements arranged approximately at right angles to three directions converts the intensity of each red, green, and blue color of the reflected light into color signals R, G, and B that represent the respective voltage values. converted. These color signals R, G, and B are converted from the reflection intensity of each color to a density value of each color in a logarithmic conversion circuit 6 and output as a color density signal (reflectance value is Rf, color density signal value is D
Then, the logarithmic conversion circuit calculates D=-1ogRf).

These color density signals are converted to an analog signal of 1 m by the A/D converter 7.
The shading circuit 8 detects uneven light emission from the light source 4 and the image sensor 5. After correcting errors caused by variations in characteristics of the constituent CCD elements, the corrected digital color density signals DR", DG", and DB" are supplied to the masking processing circuit 9.

The masking processing circuit 9 outputs a digital color density signal DR.
, DG", DB", output signals C, M, Y representing the ink amount of each color of cyan, maze, tan, and yellow.
and calculate these output signals C, M.

Y is supplied to a printing device (not shown) via a halftone processing circuit 10 that performs dither processing and the like. 11 is each of the above circuits 7-
10 and a motor 2.

As a specific example of the masking processing circuit 9, for example, as disclosed in Japanese Patent Laid-Open No. 60-216670, coefficients representing characteristics of printing ink and digital color density signals DR", DG", DB" are used. It is composed of a plurality of read-only memories that fixedly store the multiplication results for each color, and an adder circuit that adds the outputs of these read-only memories.

[Problems to be Solved by the Invention] However, since the conventional masking processing circuit 9 described above forms an output signal representing the ink amount from the digital color density signals DR", DG", and DB", the image sensor 5 It is necessary to supply the color signals R2G and B obtained from the logarithmic conversion circuit 6 in advance to form the color density signals DR', DG', and DB', and the circuit of the color image reading device including the logarithmic conversion circuit 6 There was a problem with the scale.

Therefore, an object of the present invention is to provide a masking processing circuit that can reduce the circuit scale of a color image reading device or the like.

[Means for Solving the Problems] The present invention can perform logarithmic transformation by storing the result of multiplying the value obtained by logarithmically transforming the value of the intensity of reflected light represented by the color signal by a coefficient in the masking processing circuit. It was developed with a focus on the ability to omit circuits, and its gist is that it is based on multiple color signals that represent the intensities of light at multiple different wavelengths, and the intensity of the light that is represented by each of the multiple color signals is determined by the concentration. A conversion table that outputs a plurality of ink amount data signals for a specific color corresponding to the converted color density, and a plurality of ink amount data signals output from the conversion table are added to calculate the ink amount of the specific color. This is because it is equipped with an adder.

[Operation of the Invention] In the masking processing circuit according to the above configuration, when a plurality of color signals representing the intensities of light of a plurality of wavelengths are supplied to the conversion table, the conversion table stores inks corresponding to the intensities of a series of lights. Since the amount data is held, the conversion table outputs a plurality of ink amount data signals each representing ink amount data corresponding to a particular light intensity represented by each of the plurality of supplied color signals. These multiple ink amount data signals represent ink amount data corresponding to the color density obtained by color density conversion of the light intensity indicated by each color signal. There is no need to perform density conversion, and the color signal can be directly supplied to the conversion table.

The plurality of ink amount data signals outputted from the conversion table in this manner are supplied to an adder, and the adder adds up the plurality of supplied ink amount data to calculate the ink amount of a specific color.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the circuit configuration of one embodiment of the present invention, and one embodiment is an example in which the present invention is applied to a color image reading device.

In FIG. 1, reference numeral 21 denotes a document on which a color image is drawn, and this document 21 is irradiated with white light from a light source 24 that receives driving force from a motor 22 and repeatedly moves three times in the direction of an arrow 23. The reflected light is detected by an image sensor 25 composed of a plurality of CCD elements arranged approximately perpendicular to the arrow 23, and the intensity of the reflected light for each color of red, green, and blue is expressed as a voltage value. It is converted into signals R, G, and B.

In this way, one document is irradiated with white light three times. The first scan is used to print with cyan ink, the second scan is used to print with magenta ink, and the third scan is performed to print with cyan ink. This is to perform printing using yellow ink based on scanning.

Color signal R9G output from the image sensor 25,
B is converted from an analog value to a digital value by the A/D converter 27 every three scans, and is converted into a digital color signal DR,
The signals are sent to the shading circuit 28 as DG and DB. The shading circuit 28 corrects errors caused by uneven light emission of the light source 24 and variations in characteristics of the CCD elements constituting the image sensor 25, and then supplies the corrected digital color signals DR, DG, and DB to the masking processing circuit 29. . The output of the masking processing circuit 29 is supplied to a printing device (not shown) via an intermediate processing circuit 29' that performs dither processing and the like.

In this embodiment, as shown in FIG.
．． 31, 32, the digital color signals DR, DG, DB supplied from the shading circuit 28, and the address signal AD supplied from the supermultiplex processing unit (MPU) 33, respectively, as the supermultiplex signal represented by the bus control signal BC. Shape calculation device 3
Selectors 34, 35, 36 selectively supply the RAM 30, 31132 based on instructions from 3, and bus control signal B.
Based on the instructions from the super heavy arithmetic unit 33 shown in C,
Output signals 0UTI, 0UT2, 0UT3 representing data related to the amount of ink read out from 0.3L32 and described later
and selectors 38, 39, 40 for sending data relating to the ink quantity to the adder 37, or supplying data relating to the ink quantity different from the data relating to the above-mentioned ink quantity from the super heavy arithmetic unit 33 to the rams 30, 31, 32. Ram 30.31
．． 32 constitutes the conversion table of the present invention as a whole.

The data related to the ink amount is the logarithm value of the calculation result on the right side when the digital color signals DR, DG, and DB are changed using the determinant shown below. Note that aee-as2 is a constant coefficient that is predetermined based on the spectral reflection characteristics, printing characteristics, etc. of cyan ink used in a printing device (not shown),
Similarly, a19 to a+2 are constant coefficients determined by the spectral reflection characteristics, printing characteristics, etc. of the magenta ink, and a2iI-A22 are constant coefficients determined by the spectral reflection characteristics, printing characteristics, etc. of the yellow ink.

Furthermore, C, M, and Y indicate the amounts of cyan ink, magenta ink, and yellow ink, respectively.

To explain in more detail, regarding the cyan ink, the ram 30 has an ass signal when the value of the digital color signal DR is changed.
The logarithm value of the XDR calculation result is stored, and the RAM 31
is a@ when changing the value of digital color signal DC.
The logarithm value of the calculation result of tXDG is memorized, and RAM 3
2 shows a when the value of the digital color signal DB is changed.
Logarithmic values of i12XDB calculation results are stored.

On the other hand, for magenta ink, the digital color signal D
a+1 when changing the values of R, DG, and DB respectively
The logarithmic values of the respective calculation results of lXDR, a++XDG, and a+2XDB are stored as immediate value data in a read-only memory (not shown) that stores program instructions for the super heavy-duty calculation unit 33. Logarithmic values of the calculation results are written to RAMs 30, 31, and 32, respectively. Similarly, for yellow ink, the logarithm values of the calculation results of A211XDR, a2+XDG, and A22XDB when the values of the digital color signals DR, DG, and DB are changed respectively are stored in the program instructions of the super heavy-duty calculation unit 33. The logarithmic values of these calculation results are read out by the superheavy calculation unit 33 and sent to the RAMs 30, 3.
1 and 32, respectively. Note that the data related to the cyan ink is also held as immediate data in a read-only memory (not shown), and when rewriting data related to the yellow ink to data related to the cyan ink, data is stored from the read-only memory to the rams 30, 31.
, 32.

Next, the rams 30, 31, 32 will be explained in detail with reference to FIG. Each RAM 30, 31, and 32 has an 8-bit address input terminal, an 8-bit data input/output terminal, a chip selection terminal C8, and a write/read control terminal W/R. Selectors 34, 35.
Digital color signals DR, DG, and DB are supplied from 36, or address signals are supplied from super-duplex calculation device 33 based on the selection of super-duplex calculation device 33. When the digital color signals DR, DG, DB are supplied to the address terminals, the RAMs 30, 31, 32 function in the read mode in response to the write/read control signal W/H, and the digital color signals DR, DG, DB are supplied to the address terminals. The data corresponding to the above ink amount stored at the address represented by the value is outputted to the adder 37 from the data input/output terminal. On the other hand, when an address signal is supplied from the super-heavy arithmetic unit 33, the super-heavy arithmetic unit 33 enters the write mode, and the super-heavy arithmetic unit 33 stores data regarding the new ink amount supplied to the data input/output terminal via the data bus DB in a read-only memory. are sequentially written to addresses indicated by address signals supplied via address bus AB. In this way, Ram 30.
An example of data related to the amount of ink held in 3132 is shown in the table below. In the table below, ass: 10110010,
Change the value of the digital color signal from oooooooooo to 1111
It shows data regarding the amount of ink when changed to 1111.

In this way, the data related to the ink amount is the logarithm value of the multiplication result of the constant coefficient and the digital color signals DR, DG, and DB, so it is held in consecutive addresses of RAM 30, 31, and 32, respectively. When the values are expressed in a graph, Ll, L2. It changes like L3.

The data related to the ink amount read out from each of the rams 30, 31, and 32 in this manner is supplied to the adder 37, where they are added together. Therefore, the output signal output from the adder 37 represents the amount of cyan ink, magenta ink, or yellow ink, and
Based on the output signal from 7, a printing device (not shown) draws partial images of cyan, magenta, and yellow, and when these partial images are combined, the image drawn on the original 21 is duplicated. become.

Next, the operation of this embodiment will be sequentially explained with reference to the flowcharts shown in FIGS. 6 to 8.

When the operator desires to make a color copy of the original 21, places the original 21 in a predetermined position, and operates a copy start switch (not shown), the super-duplex arithmetic unit 33 outputs the bus control signal B.
Select C34. 35° 36 and selector 3B, 39
．． address bus AB and RAM 30.40, respectively. 31. Connect with the address terminal of 32,
Furthermore, the data bus DB and the data input/output terminals of the RAMs 30, 31, and 32 are connected. As a result, Ram 30. 31
．． 32 is placed under the control of the superheavy computing device 33, and data related to the amount of ink can be transferred (step Sl).
.

When the RAMs 30, 31, and 32 are placed under the control of the super-heavy-duty arithmetic unit 33, the super-heavy-duty arithmetic unit 33 changes to address address (00
000000) to address number (11111111)
Address signals representing addresses that are sequentially incremented up to
output to the data bus in synchronization with the address signal. As a result, data corresponding to the amount of cyan ink is written to the addresses of the rams 30, 31, and 32 that are successively incremented (step S2).

When all the data related to the amount of cyan ink are written to the RAMs 30, 31, and 32, the superheavy calculation unit 33 again operates the bus control signal BC to select the selector 34.
35. 36. 38. 39 and 40, the shading circuit 28 is connected to the address terminals of the RAMs 30, 31, and 32, and their data input/output terminals are respectively connected to three sets of input terminals of the adder circuit 37. As a result, the read/write memories 30, 31, and 32 are no longer under the control of the superheavy processing unit t33, and the shading circuit 28
Digital color signals DR, DG supplied from

Selector 38.39.4 selects the data regarding the amount of cyan ink held at the address of the value represented in the DB.
0 to the adder 37 (step S3).

Thereafter, the superheavy calculation device 33 determines whether or not there is a first scanning request for the document 21 from a host computer (not shown) (step S4), and while the determination result in step S4 is NO (N), Step S4 is repeated to wait for the first scan request from the host computer.

Eventually, when the first scanning request is made and the judgment result in step S4 becomes yes (Y), the superheavy calculation unit 33
gives a start command to the motor 22, and the motor 22 starts rotating. As a result, the motor 22 moves the illuminated light source 24 along the original 21, and the first scanning of the original 21 is started (step S5). White light irradiated onto the original 21 from the light source 24 is reflected by the original 21, and the intensity of this reflected light reflects the shape and color of the image drawn on the original 21. Therefore, the image sensor 2 receiving the reflected light
5 are voltage color signals R, G corresponding to the respective intensities of the red light component, green light component, and blue light component in the reflected light;
B is continuously formed during the scanning period, and these color signals R, G
, B are sequentially supplied to the A/D converter 27. The A/D converter 27 outputs color signals R, G, and R at a predetermined sampling frequency.
B is sampled to form digital color signals DR, DG, and DB having values corresponding to the sampled voltage values.

The voltage values represented by the color signals R, G, and B change as the document 21 is scanned and change in accordance with the shape and color of the image drawn on the document 21. Therefore, the digital color signal DR
, DG, and DB also change as the original 21 is scanned. Therefore, digital color signals DR, DG, and DB whose values change sequentially as the original 21 is scanned are supplied to each address terminal of the rams 30, 31, and 32. The following description focuses on the digital color signals DR, DG, and DB at a specific time after the start of scanning.

As already explained, in step S3, the selectors 34, 35, 36 select the shading circuit 28 and the ram 30.
, 31, and 32, respectively, so the digital color signals DR, DG, and DB are connected to the RAM 30,
As a result, data regarding the amount of cyan ink at the addresses indicated by the values of these digital color signals DR, DG, and DB are input to the data input terminals of RAMs 30, 31, and 32, respectively. Appears on each output terminal. Selector 38. 39. 40 is the ram 30, 31 . Since the data input/output terminal of 32 and the input terminal of adder 37 are connected,
The data regarding the amount of cyan ink is added by the adder 37, and as a result, an output signal representing the amount of cyan ink expressed as C=aeeXDR+aetXDG+aθ2XDB appears at the output of the adder 37. This output signal representing the amount of cyan ink is supplied to a printing device (not shown), and one coat of cyan ink is applied to the paper at a position corresponding to the position of the original 21 at a predetermined time after the first scanning of the original 21 starts. The image portion of the line is printed.

Digital color signals DR, DG, DB that change as the original 21 is scanned by cyan ink printing as described above.
When performed continuously based on the method, image portions of cyan ink are formed on the paper.

Eventually, when the scanning of the original 21 is completed, the super-heavy arithmetic unit 33 gives a reverse rotation command to the motor 22, and as the motor 22 reverses, the light source 24, which has been turned off, starts a return operation (step S6). After the first scanning of the original 21 is completed, the superheavy-type arithmetic unit 33 again sends the bus control signal BC to the selector 34. 35° to 36, 38, 39, and 40 to connect the address bus AB and the address terminals of the RAMs 30, 31, and 32, and connect the data input/output terminals of the RAMs 30, 31, and 32 to the data bus DB. As a result, Ram 30
, 31, and 32 are again placed under the control of the superheavy computing device 33 (step S7).

When the RAMs 30, 31, and 32 are placed under the control of the superheavy arithmetic unit 33 again, the superheavy arithmetic unit 33 changes the address address (
00000000) to address number (1111111
Address signals representing addresses sequentially incremented up to 1) are placed on the address bus AB, and data regarding the amount of magenta ink to be written to these addresses is sent to the data bus DB in synchronization with the address signals while controlling the chip selection signal cs. Output. As a result, Ram 30. 31. 32
The data corresponding to the amount of magenta ink is written to the sequentially increasing addresses (step S8).
).

When all the data related to the ink amount of magenta ink are written to the RAMs 30, 31, and 32, the super heavy-duty arithmetic unit 33 operates the bus control signal BC again to select the selector 34.
．． 35. 36. 38. Switch 39°40,
The shading circuit 28 is connected to the address terminals of RAMs 30, 31, 32, and their data input/output terminals are connected to the adder circuit 37.
03 sets of input terminals. As a result, the RAMs 30, 31, and 32 are no longer under the control of the superheavy processing unit 33, and the magenta ink stored at the address of the value represented by the digital color signals DR, DG, and DB supplied from the shading circuit 28 is removed. The data between the ink amounts are sent to the adder 37 via the selectors 3B and 39.40, respectively.
(Step S9).

After this, the superheavy calculation device 33 determines whether the return operation of the light ff24 that has already started has been completed (step 5IO), and repeats step 510 while the determination result in step S10 is NO (N). Wait until the return operation of the light source 24 is completed.

Eventually, the return operation of light [24 is completed and step 5
When the result of the determination in step 10 is YES (Y), the super-heavy type arithmetic unit 33 gives a start command to the motor 22, and the motor 22 starts normal rotation. As a result, the motor 22 turns the light source 2 on.
4 is again moved along the original 21, and the second scanning of the original 21 is started (step 5ll). The white light irradiated from the light source 24 to the original 21 is reflected by the original 21,
The intensity of this reflected light also reflects the shape and color of the image drawn on the original document 21. Therefore, the image sensor 25 that receives the reflected light sends color signals R, G, and B of voltages corresponding to the respective intensities of the red light component, green light component, and blue light component in the reflected light during the second scanning period. These color signals R, G, and B are sequentially supplied to the A/D converter 27. The A/D converter 27 samples the color signals R, G, and B at a predetermined sampling frequency, and forms digital color signals DR, DG, and DB having values corresponding to the sampled voltage values.

The voltage values represented by the color signals R, G, and B change as the document 21 is scanned and change in accordance with the shape and color of the image drawn on the document 21. Therefore, the digital color signal DR
, DG, and DB also change as the original 21 is scanned. Therefore, digital color signals DR, DG, and DB whose values change sequentially as the document 21 is scanned for the second time are supplied to each address terminal of the rams 30, 31, and 32.

As already explained, in step S9, the selectors 34, 35, 36 select the shading circuit 28 and the ram 30.
, 31 and 32 are connected to the address terminals, respectively, so that the digital color signals DR, DG, whose values change sequentially,
DB is Ram 30. 31. These digital color signals DR, DG are supplied to 32 address terminals, respectively.
, DB appear at the data input/output terminals of the RAMs 30, 31, and 32, respectively. Selector 3B, 3
9°40 is the ram 30.31. in step S9. 3
Since the data input/output terminal of No. 2 and the input terminal of the adder 370 are connected, the data regarding the amount of magenta ink is added by the adder 37, and as a result, the output of the adder 37 is M::a+aXDR+a++XDG. An output signal representing the amount of magenta ink represented by +a12xD B is sequentially output. This output signal representing the amount of magenta ink is sequentially supplied to a printing device (not shown), and an image portion is printed with magenta ink at a position on the paper corresponding to the position of the document 21 being scanned.

As described above, the digital color signals DR and DG change as the second scanning of the original 21 progresses.

The amount of magenta ink is continuously calculated based on the DB, and an image portion of magenta ink is formed on the paper corresponding to the amount of ink.

Eventually, when the second scanning of the original 21 is completed, the super-heavy-type arithmetic unit 33 gives a reverse rotation instruction to the motor 22, and as the motor 22 reverses, the light source 24, which has been turned off, starts its return operation again (step 512). . 2nd part of manuscript 21
After the completion of the second scan, the superheavy-type arithmetic unit 33 again sends the bus control signal BC to the selectors 34, 35, 36, 38, 39, 4.
0 to address bus AB and RAM 30. 31.
32 address terminal, and ram 30, 31゜3.
The data input/output terminal of No. 2 is connected to the data bus DB.

As a result, the rams 30, 31, and 32 are again placed under the control of the superheavy computing device 33 (step 513).

When the RAMs 30, 31, and 32 are placed under the control of the superheavy arithmetic unit 33 again, the superheavy arithmetic unit 33 changes the address address (
00000000) to address number (1111111
Address signals representing addresses sequentially incremented up to 1) are placed on the address bus AB, and data regarding the amount of yellow ink to be written to these addresses is output to the data bus in synchronization with the address signal while controlling the chip selection signal C8. do. As a result, data regarding the amount of yellow ink is written in each of the sequentially advancing addresses of the rams 30, 31, and 32 (step 514).

When all the data regarding the amount of yellow ink is written into the read/write memories 30, 31 and 32, the super heavy arithmetic unit 33 again outputs the bus control signal BC.
Operate selector 34, 35. 36, 38, 39.4
0, and the shading circuit 28 is switched to RAM 30,3.
1.32 address terminals, and their data input/output terminals are connected to the input terminals of the adder circuit 3703, respectively.

As a result, the rams 30, 31, 32 are
The digital color signals DR and DG are supplied from the shading circuit 28 and are not under the control of the shading circuit 28.

Selectors 38, 39.
40 to the adders 37 (step 515).

After this, the superheavy calculation device 33 determines whether the return operation of the light source 24 that has already started has been completed (step 516), and if the determination result in step S16 is NO (
During step N), step 916 is repeated to wait for the return operation of the light source 24 to be completed.

Eventually, the return operation of the light source 24 is completed and step 9
When the result of the determination in step 16 is YES (Y), the super-heavy type arithmetic unit 33 gives a start command to the motor 22, and the motor 22 starts normal rotation. As a result, the motor 22 turns the light source 2 on.
4 is again moved along the original 21, and the third scanning of the original 21 is started (step 517). The white light irradiated onto the original 21 from the light source 24 is reflected by the original 21,
The intensity of this reflected light also reflects the shape and color of the image drawn on the original document 21. Therefore, the image sensor 25 that receives the reflected light continuously sends color signals R, G, and B of voltages corresponding to the respective intensities of the red light component, green light component, and blue light component in the reflected light during the scanning period. and these color signals R,G.

B is sequentially supplied to the A/D converter 27. 'The A/D converter 27 receives color signals R, G,
A digital color signal DR having a value corresponding to the sampled voltage value.

Form DG and DB.

The voltage values represented by the color signals R, G, and B change as the document 21 is scanned and change in accordance with the shape and color of the image drawn on the document 21. Therefore, the digital color signal DR
, DG, and DB also change as the original 21 is scanned. Therefore, digital color signals DR, DG, and DB whose values change sequentially as the document 21 is scanned for the third time are supplied to each address terminal of the rams 30, 31, and 32.

As already explained, in step S15, the selector 34
゜35.36 is the shading circuit 28 and the ram 30゜3
1.32 address terminals are connected to each other, so the digital color signals DR, DG, DB whose values change sequentially
are supplied to the RAM 30, 31, 32 (7) address terminals, respectively, and these digital color signals DR, DG, D
Data corresponding to the amount of yellow ink at the address indicated by the value B appears at the data input/output terminals of the rams 30, 31, and 32, respectively. Selector 38, 39.40
connects the data input/output terminals of the rams 30, 31, and 32 and the input terminal of the adder 370 in step S15, so the data between the ink amounts of yellow ink is added by the adder 37, and as a result, the addition At the output of the device 37, an output signal representing the amount of yellow ink expressed as Y=a2eXDR+a2+XDG+a22XDB is sequentially generated. This output signal representing the amount of yellow ink is sequentially supplied to a printing device (not shown), and an image portion is printed with yellow ink at a position on the paper corresponding to the position of the document 21 being scanned.

As described above, as the original 21 is scanned for the third time, the digital color signals DR and DG change sequentially.

The amount of yellow ink is continuously calculated based on the DB, and an image portion of the yellow ink is formed on the paper with the amount of ink represented by the calculation result based on the calculation result. When a total of three scans are completed in this way, the image portion drawn with cyan ink, the image portion drawn with magenta ink, and the image portion drawn with yellow ink are superimposed, and the entire document 21 is created. The drawn image is reproduced on the paper.

Eventually, when the scanning of the original 21 is completed, the superheavy type arithmetic unit 33 gives a reverse rotation command to the motor 22, and as the motor 22 reverses, the light source 24, which has been turned off, starts its return operation again (step 518).

After the third scanning of the original 21 is completed, the superheavy-type arithmetic unit 33 again sends the bus control signal BC to the selectors 34, 35,
36, 38, 39.40 to connect the address bus AB and the address terminals of the RAMs 30, 31.32, and connect the data input/output terminals of the RAMs 30, 31, 32 to the data bus D.
Connect to B.

As a result, the rams 30, 31, and 32 are again placed under the control of the superheavy computing device 33 (step 519).
When 31 and 32 are placed under the control of the superheavy arithmetic unit 33 again, the superheavy arithmetic unit 33 changes the address address (00000
Address signals representing addresses that step sequentially from address number (000) to address address (11111111) are placed on address bus AB, and data regarding the amount of cyan ink to be written to these addresses is synchronized with the address signal while controlling chip selection signal C8. and outputs it to the data bus DB. As a result, Ram 30. 31. Data corresponding to the amount of cyan ink is written to 32 sequentially incremented addresses (step 520).

When all the data regarding the amount of cyan ink are written into the read/write memories 30, 31, 32, the superheavy calculation unit 33 again operates the bus control signal BC to select the selectors 34, 35, 36, 38, 39, . 40
switch the shading circuit 28 to the rams 30, 31
, 32, and their data output terminals are connected to the input terminals of the adder circuit 3703, respectively.

As a result, the rams 30, 31, 32 are
The digital color signals DR and DG are supplied from the shading circuit 28 and are not under the control of the shading circuit 28.

Selector 38.39.4 selects the data regarding the amount of cyan ink held at the address of the value represented in the DB.
0 to the adder 37 (step 521).

After this, the superheavy calculation device 33 determines whether the return operation of the light source 24 that has already started has been completed (step 522), and if the determination result in step s22 is NO (
During step S22, the process waits for the return operation of the light source 24 to be completed.

Eventually, the return operation of the light source 24 is completed and step S
If the judgment result in step 22 is yes (Y), step S4
Return to , and prepare for a new document scanning request.

In the above embodiment, the data regarding the ink amount is stored as immediate value data in a read-only memory (not shown), but only the constant coefficient alle-a22 is held as immediate value data, and the data between the ink amount and the ink amount are stored as immediate value data. 0oooooooo~11111 to the above constant coefficient with the shape calculation device
Multiply by 111, find the logarithm of the multiplication result, and get the address ooooo.

You may write sequentially from 00 to 11111111.

Next, another embodiment of the present invention will be described with reference to FIG. In this other embodiment, the conversion table has three rams 41.
, 42.43, and these rams 41, 4
The output of 2.43 is supplied to an adder 44. These rams41. 42 and 43 hold all data regarding the amounts of cyan ink, magenta ink, and yellow ink. That is, the ram 41 holds data regarding the amounts of cyan ink, magenta ink, and yellow ink for the digital color signal DR, and the ram 42 holds data regarding the amounts of cyan ink, magenta ink, and yellow ink for the digital color signal DG. Data related to the amount of ink is held. Also,
The RAM 43 holds data regarding the amounts of cyan ink, magenta ink, and yellow ink for the digital color signal DB. Since the data regarding the ink amount of each color is in a different address space, the digital color signals DR, DG, and DB undergo address conversion every time the scan is performed. However, unless the constant coefficient of the determinant described above has to be changed due to a change in ink used, there is no need to rewrite the data related to the amount of ink for each scan, reducing the burden on the superheavy calculation unit. can be done.

Note that in the second embodiment, the conversion table is constructed using a RAM, but if the ink used is not to be changed, the conversion table may be constructed using a read-only memory instead of the RAMs 41, 42, and 43. good.

Next, selector 34 of the first embodiment. 35°36.
FIG. 10 shows a partial configuration of a third embodiment in which a 3-state gate is used in place of 3B, 39.40.

When the bus control signal BC is at a high level, the MPU 33 and the RAMs 30, 31, 32 are disconnected and the digital color signal D is output.
Data corresponding to the ink amount stored at the address represented by the values of R, DG, and DB is output from the input/output terminal of the ram to the adder.

When the bus control signal BC is at a low level, RAM 30.31.
32 is placed under the control of MPtJ33, and MPU33 is enabled to write data to RAM 30.31.32. In this case, the contents of the data bus DB will flow to the adder, but no problem will occur if the printing operation is prohibited as appropriate.

In the above embodiment, explanation regarding the positive and negative values of alIs-622 has been omitted, but since some coefficients may be negative, it is preferable to use an adder 37 of a type capable of signed addition. . At this time, as for the coefficient data to be written to the RAM, the most significant bit is the sign bit, and the complement is written in advance, or since it is known in advance which data will be a negative number, the code control circuit is connected to the RAM 30, 31. .32 and adder 37
and for negative coefficients, MPU 33
It is only necessary to control the sign control circuit to calculate a negative number from the above.

[Effects of the Invention] As described above, according to the present invention, a plurality of ink amount data regarding a specific color corresponding to a color density obtained by converting the intensity of light each represented by a plurality of color signals into a conversion table is stored in a conversion table. Since the masking processing circuit according to the present invention is retained, there is no need to perform color conversion in advance on the color signal representing the intensity of light, and a color image reading device or the like employing the masking processing circuit according to the present invention has the effect that the circuit scale can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing the configuration of a color image reading device that employs a masking processing circuit according to an embodiment of the present invention, and FIG. 2 shows the configuration of a color image reading device including a conventional masking processing circuit. 3 is a block circuit diagram showing the detailed configuration of a masking processing circuit according to one embodiment; FIG. 4 is a plan view showing the arrangement of ram bins used in the masking processing circuit according to one embodiment. , FIG. 5 is a graph showing an example of data related to the amount of ink held in the ram shown in FIG. FIG. 9 is a block circuit diagram showing the configuration of another embodiment of the present invention, and FIG. 10 is a block diagram showing the configuration of a third embodiment of the present invention. 21... Original document, 25... Image sensor, 27... A/D converter, 28... Shading circuit, 29... Masking processing circuit, 30- 32...Ram (conversion table), 33...Super heavy-duty processing unit (MPU) 37.44.φ adder, 41-43...Ram (conversion table). Patent applicant Minolta Camera Co., Ltd. Agent
Patent Attorney Kiyoshi Kuwai - (1 other person) Figure 4 Figure 5 Figure 8

Claims (1)

[Scope of Claims] Ink relating to a specific color corresponding to a color density obtained by converting the intensity of light represented by a plurality of color signals based on a plurality of color signals each representing the intensity of light of a plurality of wavelengths different from each other. Masking comprising a conversion table that outputs a plurality of ink amount data signals each representing amount data, and an adder that adds the plurality of ink amount data signals output from the conversion table to calculate the ink amount of a specific color. processing circuit.