JPH02141878A - Image reader - Google Patents

Abstract

PURPOSE:To obtain a monochrome output being approximate to a lightness component at a high speed by converting three primary color outputs from a color line sensor to digital data, executing division and addition so as to become a ratio in which a converter, and three primary color digital data from this A/D converter can be approximated to the lightness component, and sending out a monochromatic output. CONSTITUTION:Three primary color outputs from a color line sensor 1 are converted to digital data, respectively by a A/D converter 4, and supplied to the corresponding primary color use shift registers 5-7, respectively. Subsequently, in each shift register thereof 5-7, division by a bit shift is executed so as to become a ratio in which the digital data of three primary colors can be approximated to a lightness component, its result is supplied to an adder 8 and added, and from the adder 8, a monochrome output being approximate to the lightness component is sent out. In such a way, the monochrome output being approximate to the lightness component can be surely obtained at a high speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image reading device using a color line sensor.

[Prior Art] For example, there are cases where it is desired to obtain monochrome binary output or gradation output using an image reading device using a color line sensor. In such a case, for example, the three primary colors R (
When using a color line sensor equipped with transmission filters for red), G (green), and B (blue), one of the R, G, and B sensor outputs is taken out as a monochrome output. .

In addition, calculations are performed on software and output as a monochrome output.

[Problems to be Solved by the Invention] However, in the case where the sensor output of any one of the R, G, and B transmission filters is output as a monochrome output, it is difficult to obtain images from white and black originals. Although monochrome output can be obtained without any problems, there is a problem in the case of monochrome originals that monochrome output cannot be obtained depending on the color.

Furthermore, in the case where a monochrome output is obtained by performing arithmetic processing on software, for example, when attempting to obtain a monochrome output that approximates the brightness component, complicated arithmetic processing is required and the processing takes time.

SUMMARY OF THE INVENTION An object of the present invention is to provide an image reading device that uses a color line sensor and can reliably obtain a monochrome output that approximates the brightness component at high speed.

[Means for Solving the Problem] The invention described in claim (1) provides an image reading device that reads an image by receiving reflected light from a document using a color line sensor in which a photosensitive portion is provided with transmission filters of three primary colors. , an A/D converter converts each of the three primary color outputs from the color line sensor into digital data, and a bit shift is performed so that the three primary color digital data from this A/D converter have a ratio that can approximate the brightness component. This system is provided with a shift register for each primary color that divides by , and an adder that adds digital data from each shift register and sends out a monochrome output.

Further, the invention described in claim (2) provides a
A register for each primary color that stores digital data for each primary color and an adder that adds the digital data from each register and sends out a monochrome output are provided, and the output data bus from each register is connected to the input data bus of the adder. By shifting the bits and connecting them, the three primary color digital data can be divided by the ratio that can approximate the brightness component by shifting the bits.

[Operation] In the invention described in claim (1), the three primary color outputs from the color line sensor are each converted into digital data by the A/D converter, and each is supplied to the corresponding primary color shift register. In each shift register, division by bit shifting is performed so that the digital data of the three primary colors has a ratio that can be approximated to the brightness component, and the results are supplied to an adder and added. As a result, the adder sends out a monochrome output that approximates the light and skin components.

Further, in the invention described in claim (2), the three primary color digital data from the A/D converter are stored in the respective corresponding primary color registers. By supplying the digital data of each primary color from each primary color register to the adder, the digital data of each primary color is converted into data that approximates the lightness component. Then, the adder performs addition of the digital data, and the adder outputs a monochrome output that approximates the brightness component.

[Example] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

In Fig. 1, 1 is a color CCD line sensor, and this sensor 1 has a large number of CCDs arranged in a row, and transmission filters for the three primary colors of R (red), G (green), and B (blue) are attached to the photosensitive area of each CCD. It is printed and placed. The CCD line sensor 1 is driven by a CCD drive circuit 2 to read an image from a document.

The three primary colors from the CCD line sensor 1, namely R,
The G and B image reading signals are supplied to the correction amplifier 3 and R
, G, and B outputs are corrected so that the integral values are the same. That is, R used in the CCD line sensor 1
, G, and H are as shown in FIG. 2, so by correcting them with the correction amplifier 3, the characteristics G and B are changed as shown in FIG. 3.
', B'.

Then, R and G output from the correction amplifier 3.

The B output is supplied to the A/D converter 4 and converted into 8-bit digital data, and the R digital data is sent to the R primary color shift register 5, the G digital data to the G primary color shift register 6, and the B digital data. The data is supplied to the B primary color shift register 7, respectively.

Shift clocks R, G, and B are input to each of the shift registers 5, 6.7, respectively, and the stored digital data is bit-shifted using the shift clocks to perform division processing. This division is done so that the digital data of the three primary colors has a ratio that approximates the brightness component.
That is, it is performed so that the ratio approximates the relative luminous efficiency of a person.

For example, to obtain a value that approximates the brightness component, ideally R:
R, G, B in the ratio of G:B-1:4.59:0.06
However, in reality, even if the ratio is not as strict as this, for example, R:G:B- at a ratio of 2:1, the content can be sufficiently approximated to the brightness component. .

Based on this, two shift clocks are supplied to each of the R shift register 5 and the B shift register 7.
A bit shift is performed to perform a division by 1/4, and only one shift clock is supplied to the G shift register 6, and a 1-bit shift is performed to perform a division by 1/2. The characteristics of the digital data output from the R, G, and B shift registers 5, 6.7 are shown in FIG.
′.

The digital data output from each of the shift registers 5, 6.7 is supplied to an adder 8 and added, and the adder 8 sends out a monochrome output having a value approximate to the brightness component shown by characteristic X in FIG. I try to do that.

According to this embodiment having such a configuration, the R, G, and B digital data output from the A/D converter 4 are converted into R, G, and B digital data, respectively.
Since the shift register 5, the G shift register 6, and the B shift register 7 divide the value to a value that approximates the brightness component, the adder 8 adds the monochrome component. The characteristics of the output will certainly be those of values that approximate the brightness component. Therefore, even when a document is read by the color CCD line sensor 1, a good monochrome output can be obtained with a density gradation approximating the brightness level that is actually perceived by a person.

In addition, since all arithmetic processing is performed by hardware, arithmetic processing can be performed quickly and monochrome output can be obtained at high speed.

Furthermore, by changing the number of input shift clocks, the contents of the division can be changed, and the proportions of R, G, and B can be easily changed.

Next, other embodiments of the present invention will be described with reference to the drawings. Note that the same parts as in the above embodiment are given the same reference numerals and detailed explanations will be omitted.

As shown in FIG. 6, these are primary color registers R register 9, G register 10, and B register instead of shift registers.
A register 11 is provided, and an output data bus o of the R register 9 is provided.
OUT of the lower 2 bits of UTo~0UT7,,0U
T1 is shifted and 0UT2 to 0UT7 are connected to input data buses RINo to RIN5 of the adder 12. G again
Shift the lowest 1 bit 0UTo among the output data buses 0UTo to 0UT7 of the register 10, and output OUT, to 0U.
T7 is the input data bus GINo-GIN6 of the adder 12.
is connected to. Further, the lower two bits of the output data buses 0UTo to 0UT7 of the B register 11 are OUT.

0UTl is shifted, and 0UT2 to OUT are connected to the input data bus BINo-BINS of the adder 12.

In this embodiment, R, G from the A/D converter 4,
The 8-bit data of B is R and G, respectively.

In the above embodiment, each shift register 5
, 6.7, the same data is input to the adder 12.

Therefore, in this embodiment as well, the adder 12
A good monochrome output will be sent out.

Moreover, in this embodiment, each of the R, G, and B registers 9.
Since the division process can be substantially performed simply by supplying the data of 10.11 to the adder 12, there is no need to supply the shift clock as in the previous embodiment, and even higher speed processing becomes possible. Therefore, monochrome output can be obtained even faster.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to provide an image reading device that uses a color line sensor and can reliably obtain a monochrome output that approximates the brightness component at high speed.

[Brief explanation of the drawing]

1 to 5 show an embodiment of the present invention. FIG. 1 is a block diagram, FIG. 2 is a spectral characteristic diagram of an R, G, and B transmission filter, and FIG. 3 is a diagram of R, G, and B transmission filters. . Figure 4 is a spectral characteristic diagram obtained by dividing the characteristics of R, G', and B', and Figure 5 is the characteristic of R'', G'', and B'. FIG. 6 is a block diagram showing another embodiment of the present invention. 1...Color CCD line sensor, 4...A/Di
converter, 5.6.7... shift register, 8.12...
- Adder, 9, 10.11... register. Figure 3 Figure 1 Figure 2 Figure 4

Claims (2)

[Claims] (1) In an image reading device that reads an image by receiving reflected light from a document with a color line sensor equipped with a transmission filter for three primary colors in the photosensitive section, the output of the three primary colors from the color line sensor is converted into digital data. An A/D converter for conversion, a shift register for each primary color that divides by bit shift so that the three primary color digital data from this A/D converter has a ratio that can be approximated to the brightness component, and a shift register for each primary color that divides by bit shift, and An image reading device comprising an adder that adds digital data of and sends out a monochrome output. (2) In an image reading device that reads an image by receiving reflected light from a document with a color line sensor equipped with a transmission filter for three primary colors in the photosensitive section, the output of the three primary colors from the color line sensor is converted into digital data. An A/D converter for conversion, a register for each primary color that stores the three primary color digital data from this A/D converter, and an adder that adds the digital data from each register and sends out a monochrome output. and connecting the output data bus from each of the registers to the input data bus of the adder with respective bits shifted, and dividing the three primary color digital data by the ratio that can approximate the brightness component by the bit shift. Characteristic image reading device.