JPH0326067A - Color picture reader - Google Patents

Abstract

PURPOSE:To simplify the constitution of a picture processing means processing such as linear interpolation, line density conversion or contour emphasis by providing a signal arrangement conversion means converting a point sequential signal into a line sequential signal. CONSTITUTION:A signal arrangement conversion means 15 converting R, G, B point sequential signals into R, G, B line sequential signals is provided to a pre-stage of a picture processing means (such as a linear interpolation circuit 12, a line density conversion circuit 13 and a contour emphasis circuit 14 or the like) whose picture processing is easier for the input of the picture information of R, G, B line sequential signals. Since three circuits have been required for a conventional reader to process three R, G, B colors simultaneously for the R, G, B point sequential signals, this system is enough to employ only one circuit. Thus, the constitution of the picture processing means such as linear interpolation, line density conversion or contour emphasis is simplified and the cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a color image reading device such as a color scanner that reads a color image using a so-called dot-sequential color image sensor.

(Prior Art) Conventionally, a contact-type CCD type color image sensor is commonly used as a so-called dot-sequential type color image sensor. The surface of this color image sensor has R(
A color separation filter of red), G (green), and B (blue) is formed, and this color filter is separated from the array of R, G, and B color filters corresponding to each sensor as shown in Figure 6. It has been purchased.

FIG. 7 shows the configuration of a color image reading device using such a color image sensor. That is, the original 2 is irradiated with light from the light source 1, and the reflected light is imaged on the color image sensor 4 configured as described above via the optical system 3. Image information is separated into three colors of R, G, and B by the R, G, and B color filters of the color image sensor 4, and is input to the color image sensor 4, where it is converted into an analog color signal. The analog color signals are sequentially output from the color image sensor 4 in time series in the order in which the R, G, and B color filters of the color image sensor 4 are lined up, as shown in FIG.

Usually, a method in which signals are sent in time series in a fixed order such as R, G, B, R, G, . . . is called a so-called point sequential method. Moreover, as shown in FIG. 9, R sequence, G sequence, B sequence, R sequence, G sequence,...
A method in which signals are sent chronologically in a fixed order is called a line sequential method.

Now, R, G, output from the color image sensor 4,
The B dot sequential analog color signal is converted to R.B by the A/D converter 5. The signals are sequentially converted into digital signals of G and B, and passed through a screening circuit 5 and a matching circuit 6, thereby correcting unevenness in the amount of light from the light source 1. After that, the image processing section (image processing means)
7 eliminates image processing such as color correction, linear interpolation, line density conversion, and edge enhancement. As shown in FIG. 10, the image processing section 7 includes a color correction circuit (color correction means) 11, a linear interpolation circuit 2, a linear density conversion circuit 13, and an edge enhancement/blurring image processing circuit 14. There is.

The color correction circuit 11 is a type of image processing for faithfully reproducing the read image information in the colors of the original. Spectral characteristics ελ of light sources, color filters, color image sensors, etc.
Due to the difference in visual characteristics between images, when comparing the color of a document and its read image information with the color displayed on a display or the like, there will be a difference in color. Therefore, in order to improve color reproducibility, the read R. , G, and B signals are corrected to R', G', and B' signals using a matrix circuit.

That is, can do.

Color replacement processing is performed from the R, G, and B signals of the same pixel using the following equation.

The linear interpolation circuit 12 performs point-sequential sensor placement correction. That is, the color image sensor 4 has R, G, and B sensors arranged adjacent to each other in the reading direction, as shown in FIG. Therefore, when reading a place on a document where the density changes rapidly, each pixel's R, G, B sensor will read the original R, G, B sensor at that point in order to read a different density point on the document. Information that differs from the ratio is read.

Therefore, by performing a linear interpolation calculation as follows, using the location of the sensor corresponding to the G color filter as a reference,
Data R and B are corrected to the data obtained from the sensor location corresponding to the 6 color filters.For example, the first
Consider the case of reading a density-changing portion a of a black-and-white document shown in FIG. 1(a). The color information of the first pixel is the data R shown in FIG. 11(b) due to the difference in the reading position of each color filter.
i, Gf, B1ε. This causes color bleeding to occur in the output image because the ratio of image information of the three colors is different even though an achromatic original is read. In the case of FIG. 11(b), since R is small and B is large, the color at this point is bluish.

Therefore, by correcting using the above formula, the data Rl, Bl
is converted to RIBl' as shown in FIG. 11(c), and color blur can be eliminated.

The linear density conversion circuit 13 has a reading density of 18 lines/Il, for example.
In order to convert the R, G, and B color signals read with a reading density of 8 lines/am, the following correction is performed.

In the contour enhancement/blurring image processing circuit 14, a conversion formula is determined based on the same color signals of pixels in the vicinity of a certain pixel to be converted.

As described above, the color correction circuit 11 performs the R. It can be seen that processing is performed using the G and B signals, and processing is performed using adjacent same color signals in the linear complementary circuit 12, the linear density conversion circuit 13, and the edge enhancement/blurring image processing circuit 14.

Up until now, all image processing circuit configurations have been handled manually using R, G, and B point sequential signals. For this reason, R, G,
Not only color correction circuits where manual input of B-point sequential signals is desirable, but also
Linear interpolation, which is preferably processed by R, G, B line sequential signals;
The circuits for line density conversion, contour enhancement, etc. are R, G. B
It was processed using point sequential signals.

Therefore, in circuit configurations such as linear interpolation, line density conversion, and edge enhancement, when performing calculations with image information of adjacent same colors, the other two colors are temporarily stored in a buffer, and then
This has the disadvantage that it is necessary to wait for the third data of the same color, which complicates the circuit structure and timing. Also, depending on the circuit, there may be a circuit for R processing, a circuit for G processing,
In some cases, a total of three circuits for B processing were required.

(Problem to be Solved by the Invention) As described above, in image processing means such as linear interpolation, line density conversion, and edge enhancement, R, G. Since the image information of the B-point sequential signal was manually generated, the circuit configuration became extremely complex and large-scale, resulting in high costs.

SUMMARY OF THE INVENTION Therefore, the present invention provides a color image reading device in which the structure of image processing means such as cotton interpolation, linear density conversion, and edge enhancement can be significantly simplified and the cost can be reduced. The purpose is to

[Structure of the Invention] (Means for Solving the Problems) The color image reading device of the present invention includes a dot-sequential color image sensor that receives light from a document, photoelectrically converts it, and outputs a dot-sequential signal. , fj array conversion means for converting a point sequential signal output from the color image sensor into a line sequential signal;
It is characterized by comprising an image processing means ε that performs predetermined image processing using the line sequential signal output from the signal array conversion means.

[Function] For example, image processing means (for example, linear interpolation,
Before each circuit (line density conversion, contour enhancement, etc.),
G. From the B point sequential signal to the R. By providing a signal arrangement conversion means to G and B line sequential signals, for example,
．． Since the three colors of R, G, and H are processed simultaneously for the B-point sequential signal, the three circuits that would have been required can be replaced with one circuit. Therefore, linear interpolation,
The configuration of image processing means for linear density conversion, edge enhancement, etc. can be significantly simplified, and costs can also be reduced.

(Example) Hereinafter, an example of the present invention will be described with reference to the drawings. In the present invention, as shown in FIG. 2, R, G, B
R, G. from point sequential digital signal. A sequential conversion circuit (signal array conversion means) 15 for converting B line sequential digital signals is provided.

The conversion circuit 15 includes, for example, a RAM, as shown in FIG.
(Random access memory) By using a buffer memory 21, line data is converted from point sequential to line sequential.

The signal HSYNC is a clock pulse that is at the "H" level while one line of data is being read from the RAM 21.

Signal WCK is used as a read/write signal for the RAM 21, a clock pulse for the write address counter 22, an input for the phase inversion circuit 25, and a select signal for the address selector 24.

Clock signal WCK2 is a signal with a frequency three times that of signal WCK, and is used as a clock for read address counter 23.

The signal COL is input to the address load signal input terminal of the read address counter 23.

Write address counter 22 generates write address signal WADR based on signal WCK. The write address signal WADR passes through the address selector 24 and is connected to the address pins of the RAM 21 that are currently being written, except for the most significant bit.

Read address counter 23 generates read address signal RADR based on signal WCK. The read address signal RADR passes through the address selector 24 and is connected to the address bins of the RAM 21 that are currently being read except for the most significant bit.

The latch circuit 26 receives R, G, and B point sequential digital signals (
The output of the color correction circuit 11) is input, and the signal WCK is input as a latch signal.

The latch circuit 27 receives the digital signal ε (output of the RAM 21) sequentially for the R, G, and B lines, as well as the latch signal LCH, which is then input as a complete sequential digital signal for the R, G, and B lines. Output.

The phase inversion circuit 25 is constituted by a D-type flip-flop 31 and an exclusive OR circuit 32, receives the signal WCK and the signal HSYNC, and outputs a signal WCKI whose phase is inverted for each line. This signal WCK1 is
It is input as a clock signal to the most significant bit of the address of the RAM 21.

The RAM 21 is a line data buffer that can store two lines of digital signals, and by changing the most significant bit of the address, one line of data area is allocated to each of the two blocks. (For example, if it is a 15-bit address RAM, OH~3f
It is divided into an area of ffH and an area of 4000H to 7fffH, and data for one line is stored in each area. )below,
The data block when the most significant bit of the address is at "L" level is called A block, and the data block when it is at "H0 level" is called B block. Figure 3 shows the timing of writing and reading from RAM21. When reading a line, the RAM 21 performs both writing and reading, but if the signal WCKI and the signal WCK are in the same phase, the signal WCKI becomes 'H-' when reading from the RAM 21.
level, read from B block, and when writing, signal WCKI becomes d L II level, and A
Write to block. Signal WCKI and signal WCK
If they are in opposite phase, the B block becomes the write area and the A block becomes the read area.

Next, the flow of operation will be explained. To simplify the explanation, consider a case where signal WCKI is the same as signal WCK. First, R
The writing to AM21 (when signal WCK is at "L" level) will be explained with reference to FIG. The R, G, and B point sequential digital signals are latched by the latch circuit 26 at the rising timing of the signal WCK.

On the other hand, from the write address counter 221 for writing,
The write address signal WADR counted up from the address "OH" is sent to the RA along with the signal WCK1.
It is input to M21 as an address signal.

Here, since the signal WCKI is at the "L" level, that is, the write area is designated in the data block A, the R, G, B point sequential digital signal latched by the latch circuit 26 is sent to the block A at the address "OH". ”, one line is written in order.

Next, the reading from the RAM 21 (when the signal WCK is at "H' level) will be explained with reference to FIG. 5. The read address signal RADR output from the read address counter 23 for continuous reading is After rising, the signal WCK2, which is three times faster than the signal WCK, is used as a clock signal to count up from the initial address roHJ.

At the timing when the selector signal input to the address selector 24 is at "H" level, the read address signal R
ADR (when outputting an address indicating the location where data R1 and data G are stored) is sequentially input to the addresses of the RAM21.

At this time, the signal WCK is at the "H" level, that is, the readout area is designated as data block B, so the current R
The image information of the previous line written in the B block of AM21 is output as shown in FIG. 5 by the read address signal RADR. This output signal from the RAM 21 is input to the latch circuit 27, and when the latch signal LCH rises, data G is cut and data R is sequentially output.

Next, when the signal COL is at the 'L' level, the initial address is set to "IH" and is counted up from there.
Similarly, data G is sequentially output. Finally, the signal CO
When the L level is "L", the initial address is set to "2H", the count is increased from there, and data B is sequentially output in the same way.

Further, when signal WCKI is in the same phase as signal WCK, block B becomes a write block, block A becomes a read block, and the above-described operations are performed.

With such a conversion circuit 15, it is possible to easily convert an R, G, B point sequential signal into an R, G, B line sequential signal. Therefore, it is easier to process images by inputting image information of R, G, and B line sequential signals (linear interpolation circuit 12
, linear density conversion circuit 13, edge enhancement/blur image processing circuit 14, etc.), it is possible to
Since three colors are processed simultaneously, the previously required three circuits for each color can now be processed with one circuit. This makes it possible to significantly simplify the configuration of the image processing unit 7 for linear interpolation, line density conversion, edge enhancement, etc., and also to reduce costs.

[Effects of the Invention] As detailed above, according to the present invention, it is possible to significantly simplify the configuration of image processing means such as linear interpolation, linear density conversion, and edge enhancement, and it is also possible to reduce costs. A color image reading device can be provided.

[Brief explanation of drawings]

1 to 5 are for explaining one embodiment of the present invention, and FIG. 1 shows a sequential conversion circuit from an R, G, B point sequential digital signal to an R, G, B line sequential digital signal. Figure 2 is a block diagram of the image processing circuit, Figure 3 is a block diagram showing the image processing circuit.
The figure is a timing chart showing timing of writing and reading from RAM, Figure 4 is a timing chart when writing image information to RAM, Figure 5 is a timing chart when image information is continuously output from RAM, and the tJs diagram is A diagram showing an example of arrangement of color filters in a contact color image sensor,
FIG. 7 is a block diagram of a color image reading device, FIG. 8 is a diagram showing the arrangement order of image signals sent in a dot sequential manner,
Fig. 9 is a diagram showing the arrangement order of image signals sent in the line sequential method, Fig. 10 is a block diagram of a conventional image processing circuit, and Fig. 11 shows the effect of linear interpolation using equation (2) above. FIG. 1... Light source, 2... Original, 3... Optical system, 4...
・Color image sensor (color image sensor), 5...
A/D converter, 7... image processing section (image processing means),
11... Color correction circuit (color correction means), 12... Linear interpolation circuit, 13... Line density conversion circuit, 14... Contour enhancement/blur image processing circuit, 15... Conversion circuit.

Claims (3)

[Claims] (1) In a color image reading device that illuminates a color original with light from a light source and reads the light from the original as an image signal, the light from the original is received, photoelectrically converted, and outputted as a dot-sequential signal. A sequential color image sensor, a signal array converting means for converting a point sequential signal outputted from the color image sensor into a line sequential signal, and a predetermined image processing using the line sequential signal outputted from the signal array converting means. 1. A color image reading device comprising: image processing means for performing image processing. (2) The apparatus further comprises a color correction means for performing color correction on the point-sequential signal outputted from the color image sensor, and the signal arrangement conversion means is installed after the color correction means. 1. The color image reading device according to 1. (3) The color image reading device according to claim 1, wherein the image processing means performs image processing such as linear interpolation, line density conversion, and edge enhancement.