JPH04170849A - Picture input device - Google Patents

Abstract

PURPOSE:To faithfully read in even the color of a region having been considered impossible to read in by a traditional device by constituting a color separation filter means of one or more sets of color correction filters in addition to the filters of each color of red (R), green (G), and blue (B). CONSTITUTION:Reflected light or transmitted light from the surface of an original 2 is color-separated by passing through the color separation filter 5 of different transmission factors, and becomes incident on an optical line sensor 6. Then, original pictures of every color component are imaged on this optical line sensor 6, and these original pictures are read in successively by a controller 7 through the optical line sensor 6. The color separation filter 5 is formed into, for instance, the form of a disk, and is constituted of four kinds of the filters including the filter R' to correct the characteristic of the negative region of F(lambda) among the isochromatic coefficients of an rgb-color system in addition to the filters divided into the transmitting regions of each color of R, G, B. Thus, even the color of the region having been considered impossible to represent by the traditional device can be faithfully represented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an image-powered device capable of reading, for example, color originals.

[Prior art]

In this type of image input device, light from the document surface is filtered by color separation filter means with different spectral transmittances (red (R) for boat fishing, red (R) for boat fishing,
The original image is color-separated by passing through three-color filters (green (G) and blue (B)) and incident on an optical line sensor (for example, a CCD), and an image of each color component is formed on the optical line sensor. is configured to read sequentially.

As such an image input device, one disclosed in, for example, Japanese Unexamined Patent Publication No. 2-89463 is known.

In the apparatus disclosed in the above-mentioned publication, color separation is performed by rotating a color disk (filter) divided into transparent areas of the three primary colors R, G, and B and sequentially switching between the two transparent areas.

In this case, the spectral sensitivity characteristic SL (λ) of the color separation signal R11 output from the optical line sensor (however.

4=r1g,b) is given by the following equation.

RA=Jp, (λ)ρ(λ)S, (λ)dλ...
(1) S, (λ)=L(λ)Fl (λ)se(λ)...(
2) However.

λ : Wavelength of light to be spectrally analyzed Pw (λ) : Spectral distribution of light source ρ (λ) : Spectral reflectance or spectral transmittance L (λ
) : Spectral transmittance of the imaging lens Fi (λ) Spectral transmittance of each area of the two-color filter se (λ) : Spectral sensitivity characteristics of the optical line sensor In such an image input device, the colors of the original are reproduced as faithfully as possible. To read, 1 spectral sensitivity characteristic S, (λ) is the color matching function 7 (λ), i (
It is necessary to have a value proportional to λ) and ■(Me) (see Figure 4).

The color of a color original is determined by the tristimulus value (R) shown below.

G, B).

...(3) Therefore, with Mr, Mg2Mb as constants.

F(λ)=MrXSr(λ) 1(λ)−MgXSg(λ)...(4)
If there is a relationship of (λ)=MbXSb(λ), substitute equation (4) into equation (3).

Using formula (1), R=MrXRr G-MgXRg (5)
B-MbxRb, and the tristimulus values of the original can be obtained from the one-color separation output.

Therefore, in the conventional device, care is taken to ensure that equation (4) approximately holds true, mainly by appropriately selecting the spectral transmittance F, (λ) of the filter.

[Problem to be solved by the invention]

However, as is clear from Figure 4, even though there is a part with values in the negative region, the 1st color function has a spectral sensitivity characteristic that only takes positive values, so it cannot be approximated. I have my own limits.

Therefore, a discrepancy occurs between the colors represented by the color separation output data in the image input device and the visual colors of the actual document.

Therefore, the purpose of the present invention is to correct the color deviation caused by the difference between the two-color function and the actual spectral sensitivity characteristic, and also to correct the color deviation in the region that was impossible to read faithfully with conventional devices. An object of the present invention is to provide an image input device having a function that allows faithful reading.

[Means to solve the problem]

In order to achieve the above object, the main means adopted by the present invention is that light from an original is color-separated by passing through color separation filter means with different spectral transmittances and then incident on an optical line sensor. In the image input device that sequentially reads document images formed on the optical line sensor for each color component, the color separation filter means:
Red (R).

In addition to green (G) and blue (B) color filters.

An image input device comprising one or more sets of color correction filters.

[Effect]

According to the image input device according to the present invention, the image data of the document is calculated from the color separation signals obtained corresponding to, for example, four types of filters, and the difference between the two color matching functions and the actual spectral sensitivity characteristics is calculated. The resulting color shift is corrected.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS Three embodiments embodying the present invention will be described below with reference to the accompanying drawings to provide an understanding of the present invention. still.

The following examples are examples embodying the present invention and are not intended to limit the technical scope of the present invention.

Here, FIG. 1 is a block diagram showing a schematic configuration of an image input device according to an embodiment of the present invention, FIG. 2 is a front view of a color separation filter constituting the image input device, and FIG. A graph showing the spectral transmittance in each region of the separation filter, and FIG. 4 is a graph showing color matching functions of RGB coloration threads.

In the image input device 1 according to this embodiment, as shown in FIG.
The light reflected or transmitted from the surface of the document 2 is color-separated by passing through a color separation filter 5 having different spectral transmittances, and is incident on an optical line sensor 6 .

A document image is formed on the optical line sensor 6 for each color component, and the document image is sequentially read by the control device 7 through the optical line sensor 6.

The color separation filter 5 is formed into a disk shape, for example, as shown in FIG. (see figure), it is composed of four types of filters including a filter R' that corrects the negative Njs characteristic of F(λ).

The filter R' may be formed by stacking a plurality of filters together with other filters R2G, B, etc.

The spectral transmittance in each transmission region of the filters R, R', G, and B is as shown in FIG. 3, for example.
The spectral sensitivity characteristic SL (λ) is 〒+(λ) TomiMrXSr (
λ) 〒-(λ)=-Mr'XSr' (λ) ・・・(
6) The relationship is as follows: i(λ)−MrXSr(λ) b(λ)=MbXSb(λ). however,? Ya (λ), 7
-(λ) represent the positive and negative parts of 7(λ), respectively. The relationship between the tristimulus values of the original and the color separation output at this time is shown for R (G.

Since B is the same as the above-mentioned formula (5), it is omitted here).

7 (λ) = r, (S) + r - (λ) = MrXSr (λ) - Mr' XS r' (λ) and the formula (
From 2) and (3).

R=MrRr-Mr'Rr'-(7)
becomes.

Therefore, if the calculation of Equation 9 (7) is performed by digital calculation after the color separation signal is A/D converted by the calculation unit 8 in the control device 7, the actual value will be lower than that in the case of the conventional device. can be visually closer to the color of the original.

In the device of this embodiment, the calculation results of the 8-color correction are stored in the memory along with the color conversion results other than those of the present invention as a look-up table, and the 1-color correction is performed by referring to the look-up table. There is.

Since the image input device l according to this embodiment is configured as described above, four types of filters R1R', G, B
By calculating the image data of the original from the color separation signals obtained correspondingly, the color shift caused by the difference between the five color isometric functions and the actual spectral sensitivity characteristics is corrected, which is considered impossible to express with conventional equipment. It is also possible to faithfully represent the colors of areas that have been previously used.

〔Effect of the invention〕

As described above, in the present invention, light from a document is color-separated by passing through color separation filter means having different spectral transmittances, and the light is caused to enter an optical line sensor.

In an image input device that sequentially reads document images formed on the optical line sensor for each color component.

The color separation filter means is red (R) and green (G).

This image input device is characterized by being configured with one or more sets of color correction filters in addition to filters for each color of blue (B), so it is possible to capture areas that were considered impossible to express with conventional devices. Colors can also be expressed faithfully.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an image input device according to an embodiment of the present invention, FIG. 2 is a front view of a color separation filter constituting the image input device, and FIG. 3 is a front view of a color separation filter constituting the image input device. A graph showing the spectral transmittance in each region, and FIG. 4 is a graph showing color matching functions of the RGB color system. [Explanation of symbols] 1... Image input device 2... Original 3.4...
Light source 5... Color separation filter 6... Optical line sensor 7... Control device 8... Arithmetic unit R, R', G, B... Filter

Claims (1)

[Claims] 1. The light from the document is color-separated by passing through color separation filter means having different spectral transmittances and incident on the optical line sensor, and an image is formed for each color component on the optical line sensor. In an image input device that sequentially reads original images, the color separation filter means includes red (R), green (G), and blue (
An image input device comprising, in addition to the filters for each color in B), one or more sets of color correction filters.