JP2013131837A - Image forming device, image forming method, and image forming program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form an image in accordance with illumination light under which an image-formed sheet or the like is observed.SOLUTION: In an image forming device 1, a color material amount determination unit 3 determines usage of color materials provided in an image recording unit 4 on the basis of image data, the image recording unit 4 forms an image on a recording medium corresponding to the image data using the color materials with the determined usage, a peak wavelength information input unit 5 acquires optical feature information of illumination light in a place where the image on the recording medium with the image formed thereon using the color materials is observed, and a color material amount control unit 6 adjusts the usage of the color materials determined by the color material amount determination unit 3 on the basis of the optical feature information.

Description

  The present invention relates to an image forming apparatus, an image forming method, and an image forming program. More specifically, the present invention relates to an image forming apparatus and an image forming method for forming an image with a color material amount corresponding to illumination light for observing an image-formed sheet or the like. And an image forming program.

  Image forming devices such as printers, copiers, facsimile machines, and composite devices form images using color materials on recording media such as paper and film in various image forming methods such as electrophotography and ink ejection. To do.

  It is known that the color formed when observing an image formed on a recording medium is strongly influenced by illumination light that illuminates the image.

  For example, under the D50 light source that is standardly used in DTP (desktop publishing), gray formed with a single color of black (K) ink having the same color condition, cyan (C), magenta (M) and Gray imaged with yellow (Y) ink is perceived as a different color under a general fluorescent lamp. Conditional color (metamerism) means that different colors appear to be the same color under certain specific conditions.

  In general, a character image is formed using black (K) monochromatic ink with emphasis on resolution, and a natural image is emphasized with respect to gradation, and cyan (C), magenta (M) and yellow ( In many cases, an image is formed using the ink of Y), but these are often mixed to form an image.

  Therefore, conventionally, image formation of image colors is performed according to the type of illumination light source (hereinafter also simply referred to as illumination light) when an image formed is observed so that the image is not perceived as a different color. There is a technique for determining an amount of a color material suitable for the color.

  And such a conventional technique, for example, if the types of commercially available light sources are the same, such as fluorescent lamps that are widely used as illumination light sources, the dispersion of spectral characteristics in individual light sources is small, Take advantage of the fact that images are less likely to be perceived as different colors when viewed. For example, the fluorescent lamp is a phosphor used, such as a high color rendering type, a three-wavelength type, a normal type, and a color temperature, for example, 3000K (bulb color), 5000K (daylight white), 6500K (daylight color), etc. If the light source classification type is the same, the illumination light is, for example, 5000K (day white) on the premise that the influence of variations in spectral characteristics of each light source is small. ), It is a technique that can be perceived as the same color regardless of the individual light sources.

  However, in recent years, white LEDs (Light Emitting Diodes) excellent in energy saving performance have been attracting attention and are widely used as illumination light sources. However, white LED light sources have a large variation in spectral characteristics. As a result, white LED light sources, like fluorescent lamps, are categorized and manufactured and distributed according to the LED, phosphor, and color temperature used. Depending on the white LED light source of each product, the difference in light color is so large that it can be perceived by the eyes.

  Therefore, when LEDs are used as illumination light when observing a formed image, variations in individual LEDs affect color perception, and in particular, variations in the emission peak wavelength of LEDs, which is one of the causes of variations, It greatly affects the perceived color. As a result, merely specifying the type of the white LED light source is insufficient to determine a color material suitable for image formation of the image color, and there is a problem that it is perceived as a different color.

  That is, for example, the emission intensity distribution of a white LED light source composed of a blue LED and a yellow phosphor is, for example, as shown in FIG. It is an intensity | strength and the peak of 600 nm vicinity is the emitted light intensity by light emission of yellow fluorescent substance. The blue LED has a sharp peak in emission intensity distribution, and the yellow phosphor has a gentle peak in emission intensity. The feature of the emission intensity distribution shape is due to the characteristics of the LED and the phosphor, and the same tendency is shown for other colors. In addition, the magnitude | size of the emitted light intensity shown in FIG. 10 is normalized by the peak of blue LED.

  As can be seen from FIG. 10, the emission intensity distribution of the manufactured white LED light source varies, and in particular, the dispersion of the peak wavelength of the blue LED and the emission intensity ratio of the blue LED and the yellow phosphor (blue LED). Since the peak is normalized, there is a large variation in the peak size of the yellow phosphor.

  When the variation in the emission intensity distribution shown in FIG. 10 is represented by a CIE-xy chromaticity diagram, it can be shown as in FIG. 11, and the chromaticity of the white LED light source obtained by manufacturing the eight chromaticities in the center of FIG. Distributed within the grid. Note that the variation in the lower right-upper left direction H1 and the variation in the upper right-lower left direction H2 in FIG. 11 are closely related to the variation in the peak of the blue LED and the variation in the emission intensity ratio between the blue LED and the yellow phosphor. ing.

  As described above, since the white LED light source has a large variation in emission intensity distribution (chromaticity), when it is sold as an illumination light source, it is broadly classified into a daytime white color as illustrated in FIG. Sold. That is, the fine classification (for example, 8 squares) shown in FIG. 12 is not adopted in order to meet the needs of consumers even in a large classification from the record of fluorescent lamps, etc., and to suppress variations. If it is limited to fine classification (mass), the number of defective products increases, the yield deteriorates, and the cost increases. Therefore, since white LED light sources are sold in a large classification, even if the types (lunch white, light bulb color, etc.) are the same, the difference in light color is large enough to be perceived by the eyes.

  As described above, since the white LED light source has a large variation in peak wavelength, for example, as shown in FIG. 13, when two objects M1 and M2 are observed under the white LED light source, they are given a perceived color. The impact may vary. That is, FIG. 13 shows how the intensity of the reflected light in the blue region (near 400 to 500 nm) of the two types of objects M1 and M2 varies depending on the variations in the peak wavelengths of the illumination lights L1, L2, and L3. Is shown.

  The object M1 has a substantially constant spectral reflectance in the blue region (around 400 to 500 nm), and even if the peak wavelengths of the illumination lights L1, L2, and L3, which are white LED light sources, vary, the following expression (1) Thus, the integrated value of the reflected light amount, that is, the intensity of the reflected light is substantially the same.

ところが、物体Ｍ２は、白色ＬＥＤ光源である照明光Ｌ１、Ｌ２、Ｌ３のピーク波長がばらついている領域において、長波長側に変化するにつれて分光反射率が増加し、照明光Ｌ１、Ｌ２、Ｌ３のピーク波長が長波長に変化するのに伴って、次式（２）で示すように、積和値、すなわち、反射光の強さが増大する。

However, in the region where the peak wavelengths of the illumination lights L1, L2, and L3, which are white LED light sources, vary, the object M2 has a spectral reflectance that increases as it changes to the longer wavelength side, and the illumination light L1, L2, and L3 As the peak wavelength changes to a long wavelength, as shown by the following equation (2), the product sum value, that is, the intensity of reflected light increases.

このように、物体Ｍ１、Ｍ２の分光反射率より、照明光Ｌ１、Ｌ２、Ｌ３のピーク波長の変化の影響は異なる。従って、図１３に示すように、例えば、照明光Ｌ２のピーク波長付近で、物体Ｍ１と物体Ｍ２の平均反射率がほぼ同じである場合、照明光Ｌ２の下では、次式（３）に示すように、積分値、すなわち、反射光の強さもほぼ同じになるが、

Thus, the influence of the change in the peak wavelengths of the illumination lights L1, L2, and L3 differs from the spectral reflectances of the objects M1 and M2. Therefore, as shown in FIG. 13, for example, when the average reflectances of the object M1 and the object M2 are substantially the same in the vicinity of the peak wavelength of the illumination light L2, the following expression (3) is given under the illumination light L2. As shown, the integrated value, that is, the intensity of reflected light is almost the same

照明光Ｌ１や照明光Ｌ３の下では、物体Ｍ１と物体Ｍ２の積分値、すなわち、反射光の強さが異なる結果となる。

Under the illumination light L1 and the illumination light L3, the integrated values of the object M1 and the object M2, that is, the intensity of the reflected light are different.

  Although the intensity of reflected light in the blue region (around 400 to 500 nm) has been described with reference to FIG. 13, the colors perceived by humans are roughly blue (400 to 500 nm), green (500 to 600 nm), and red (600 to The same result is obtained because the intensity of light in the three regions (700 nm) is affected.

  Accordingly, when there is a variation in the peak wavelength of the illumination light, for example, the reflectance of the object M2 is increased under the illumination light L1 in FIG. 13, and the reflectance of the object M2 is decreased under the illumination light L3. The intensity of the reflected light of the object M1 can be made uniform. That is, when the reflectance of the object M2 is controlled by the amount of the color material or the like, the intensity of the reflected light can be made uniform by adjusting the amount of the color material.

  In addition, the influence on the perception due to the variation in the peak wavelength of the illumination light is particularly remarkable when it has a steep peak like the emission of a blue LED, and when it has a gentle peak like a yellow phosphor, small.

  When recording a color image with an image forming apparatus, it is common to use four color materials (ink, toner, etc.) of cyan (C), magenta (M), yellow (Y), and black (K). However, when the above-described objects M1 and M2 are shown with respect to these color materials, the spectral reflectance in the blue region (around 400 to 500 nm), particularly in the range where the peak wavelength of the blue LED varies, The change is large in the case of cyan (C) ink and yellow (Y) ink while it is almost constant in black (K) ink. Therefore, the color for forming an image mainly using cyan (C) ink or yellow (Y) ink is easily affected by variations in the peak wavelength of illumination light.

  In recent years, in order to widen the color reproduction range, an increasing number of image forming apparatuses use intermediate color materials such as red (R), green (G), and blue (B). ), The change in spectral reflectance in the range where the peak wavelength of the blue LED varies is larger than that of cyan (C) ink and yellow (Y) ink. More easy to receive. Therefore, an image formed using a color material having an intermediate hue such as red (R), green (G), and blue (B) has a more serious problem that the perceived color is different.

  Conventionally, a color processing method for estimating a light source using a light source estimation check pattern including a reference pattern and a sample patch corresponding to each of a plurality of light sources, and perceiving a color close to the reference pattern based on a user instruction A color processing method has been proposed in which the type of the sample patch is identified and color processing is performed in accordance with the estimated light source (see Patent Document 1). That is, in this prior art, the user selects the type of light source and performs color processing according to the selected type of light source.

  However, in the prior art described in the above publication, since color processing is performed according to the type of light source selected by the user, color processing according to the type of light source can be performed. As described above, the problem of being perceived as a different color due to variations in peak wavelengths of individual light sources within the type of light source cannot be solved, and improvement is required.

  Therefore, an object of the present invention is to perform image formation in which color processing is performed in consideration of variations in individual illumination light when an image is observed.

  In order to achieve the above object, the image forming apparatus according to claim 1 includes a predetermined number of color materials, and forms an image on a recording medium using the color materials according to image data. The color material amount determining means for determining the amount of the color material used by the image forming means based on the image data, and the recording medium on which the image is formed using the color material. A light information acquisition unit that acquires light feature information of illumination light of a place to be illuminated; a color material use amount adjustment unit that adjusts a use amount of the color material determined by the color material amount determination unit based on the light feature information; It is characterized by having.

  According to the present invention, it is possible to perform image formation in which color processing is performed in consideration of variations in individual illumination light when an image is observed.

1 is a block diagram of a main part of an image forming apparatus to which an embodiment of the present invention is applied. The block block diagram which shows an example of a peak wavelength information input part. The block block diagram which shows the other example of a peak wavelength information input part. The block block diagram which shows the further another example of a peak wavelength information input part. The figure which shows an example of an evaluation chart. The figure which shows the relationship between the reference patch of an evaluation chart, an evaluation patch, and the peak wavelength of blue LED. The block block diagram of a color material amount control part. The other block block diagram of a color material amount control part. 5 is a flowchart showing image forming processing. The figure which shows an example of the light emission intensity distribution of a white LED light source. The CIE-xy chromaticity diagram of a white LED light source. The figure which shows an example of the LED classification currently sold. The figure which shows the relationship between the reflectance of an object, and the dispersion | variation in illumination light.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, since the Example described below is a suitable Example of this invention, various technically preferable restrictions are attached | subjected, However, The range of this invention is unduly limited by the following description. However, not all the configurations described in the present embodiment are essential constituent elements of the present invention.

  1 to 9 are diagrams showing an embodiment of an image forming apparatus, an image forming method, and an image forming program according to the present invention. FIG. 1 shows an image forming apparatus, an image forming method, and an image forming program according to the present invention. 1 is a block diagram of a main part of an image forming apparatus 1 to which an embodiment is applied.

  In FIG. 1, an image forming apparatus 1 is a printer apparatus, a copying apparatus, a facsimile apparatus, a composite apparatus, or the like, and includes an image input unit 2, a color material amount determination unit 3, an image recording unit 4, a peak wavelength information input unit 5, and a color. A material amount control unit 6 and the like are provided.

  The image input unit 2 captures image data into the image forming apparatus 1 and outputs the captured image data to the color material amount determination unit 3. The image input unit 2 forms an image of image data sent from a host device such as a scanner or a personal computer connected via a network or the like, for example, by scanning an image of an original and scanning the image data into the image forming apparatus 1. A network interface to be taken into the apparatus 1, a USB (Universal Serial Bus) interface to take in image data of an image taken with a digital still camera or the like into the image forming apparatus 1, and a document to be installed in a host device such as a personal computer Image data of a document created by application software such as creation software or spreadsheet software is sent to the image input unit 2.

  Based on the image data input from the image input unit 2, the color material amount determination unit (color material amount determination unit) 3 calculates the color material amount included in the image recording unit 4, that is, an image of the color represented by the image data. The color material amount suitable for image formation in the image recording unit 4 is determined.

  The image recording unit (image forming means) 4 includes color materials such as C (cyan), M (magenta), Y (yellow), and K (black), and a predetermined image forming method, for example, an electrophotographic method. Based on the amount of the color material determined by the color material amount determination unit 3 by an ink ejection method or the like, an image is formed on the recording medium such as paper or film using the color material.

  A peak wavelength information input unit (optical information acquisition unit) 5 acquires peak wavelength information (light feature information) of illumination light when observing an image formed on the recording member by the image recording unit 4, and a color material Output to the quantity control unit 6. The peak wavelength information input unit 5 acquires the peak wavelength information of the illumination light at the most important place where the image formed on the recording member by the image recording unit 4 is observed, and the peak wavelength information like the spectral intensity distribution of the illumination light is obtained. It is not limited to acquiring information directly indicating the wavelength, and as described later, it is possible to estimate the peak wavelength such as the measurement result of the chromaticity of the illumination light and the patch observation result for determining the peak wavelength. Information that can be obtained may be acquired.

  The color material amount control unit (color material usage amount adjusting unit) 6 controls the color material amount determined by the color material amount determination unit 3 based on the peak wavelength information input from the peak wavelength information input unit 5. The color material amount control unit 6 takes into account, for example, the type of illumination light source, and the color determined by the color material amount determination unit 3 according to the detected or estimated peak wavelength of illumination light based on the peak wavelength information. Control the amount of material.

  And the said peak wavelength information input part 5 is provided with the spectral intensity distribution measurement part 11 and the illumination light analysis part 12, for example as shown in FIG. 2, and the illumination light analysis part 11 is a standard spectral intensity distribution memory | storage part. 13, illumination light type determination unit 14, variation determination unit 15 and the like.

  The spectral intensity distribution measuring unit (spectral intensity distribution measuring unit) 11 measures the spectral intensity distribution of ambient light, and uses the measured spectral intensity distribution as an illumination light type determination unit 14 and a variation determination unit 15 of the illumination light analysis unit 12. The image recording unit 4 is installed at a place where the recording medium on which the image is formed is observed. That is, the spectral intensity distribution measuring unit 11 measures the spectral intensity distribution of the surrounding illumination light when the image recording unit 4 observes the image formed on the recording medium.

  The illumination light analysis unit 12 determines the peak wavelength of the illumination light based on the spectral intensity distribution of the illumination light input from the spectral intensity distribution measurement unit 11.

  That is, the spectral intensity distribution storage unit 13 includes various illumination lights, for example, spectral intensity distributions such as a standard illuminant D65 light source, an A light source, and an auxiliary standard illuminant D50 light source, a high color rendering such as a light bulb color, a neutral white color, and a daylight color, and three wavelengths. The spectral intensity distribution (standard spectral intensity distribution) of the standard light source in the spectral intensity distribution of the shape, the ordinary fluorescent lamp light source, and the spectral intensity distribution of the white LED light source such as the bulb color and daylight white is stored.

  The illumination light type determination unit 14 compares the various spectral intensity distributions stored in the spectral intensity distribution storage unit 13 with the spectral intensity distribution of the illumination light input from the spectral intensity distribution measurement unit 11, and the spectral intensity distribution is the highest. The type of similar illumination light is determined, and the illumination light type that is the determination result is output to the color material amount control unit 6 and the variation determination unit 15. The spectral intensity distribution storage unit 13 and the illumination light type determination unit 14 function as illumination light type determination means as a whole.

  The variation determination unit (peak wavelength detection means) 15 determines the variation in the spectral intensity distribution within the type of illumination light determined by the illumination light type determination unit 14. For example, when the illumination light type determination unit 14 determines that the type of illumination light is a light bulb color or daylight white LED light source, the variation determination unit 15 determines the spectral intensity of the illumination light input from the spectral intensity distribution measurement unit 11. Based on the distribution, the peak wavelength of the blue LED mounted on the white LED light source of light bulb color or daylight white is detected, and the peak wavelength is output to the color material amount control unit 6.

  The spectral intensity distribution measurement unit 11 and the illumination light analysis unit 12 described above are connected by, for example, short-range wireless communication such as Bluetooth (registered trademark) or a network such as the Internet, and the spectral intensity distribution measurement unit 11 is portable. It has become. Therefore, the illumination light measurement when observing the image formed on the recording member by the image recording unit 4 can be easily performed at a position away from the illumination light analyzing unit 12, that is, the image forming apparatus 1.

  The peak wavelength information input unit 5 includes, for example, a tristimulus value measurement unit 21 and an illumination light analysis unit 22 as illustrated in FIG. 3, and the illumination light analysis unit 22 includes an illumination light type setting unit 23, A chromaticity conversion unit 24 and a variation determination unit 25 may be provided.

  The peak wavelength information input unit 5 includes a tristimulus value measurement unit 21 and an illumination light analysis unit 22 connected via, for example, a short-range wireless communication such as Bluetooth or a network such as the Internet. It is portable. Therefore, tristimulus measurement when observing an image formed on the recording member by the image recording unit 4 can be easily performed at a position away from the illumination light analyzing unit 22, that is, the image forming apparatus 1.

  The tristimulus value measurement unit (coloring measurement means) 21 measures the tristimulus values XYZ of ambient light, outputs the measured tristimulus values to the chromaticity conversion unit 24 of the illumination light analysis unit 22, and records the image. The unit 4 is installed at a place where an image formed on the recording member is observed.

  The illumination light analyzer 22 determines the peak wavelength of the illumination light based on the xy chromaticity indicated by the tristimulus values XYZ of the illumination light input from the tristimulus value measurement unit 21.

  That is, the illumination light type setting unit (illumination light type acquisition unit) 23 sets the type of illumination light where the image recording unit 4 observes the image formed on the recording member and is set by the user. The seed is output to the color material amount control unit 6 and the variation determination unit 25. Illumination light type settings include, for example, D65 light source, A light source, D50 light source, high color rendering type such as light bulb color, day white color, daylight color, three wavelength type, ordinary fluorescent light source, light bulb color, day white color, etc. A method is used in which a user selects a closest light source from among standard light source types such as a white LED light source with a switch or the like.

  The chromaticity conversion unit 24 calculates the xy chromaticity from the tristimulus values XYZ of the illumination light input from the tristimulus value measurement unit 21 and outputs the xy chromaticity to the variation determination unit 25.

  The variation determination unit (peak wavelength detection means) 25 determines the variation in xy chromaticity within the type of illumination light set by the illumination light type setting unit 23 and predicts the peak wavelength. For example, when the illumination light type setting unit 23 sets the type of illumination light to be a light bulb color or a white LED light source of day white, the peak of the blue LED is based on the xy chromaticity calculated by the chromaticity conversion unit 24. The wavelength is predicted, and the predicted peak wavelength is output to the color material amount control unit 6. For example, the variation determination unit 25 predicts the peak wavelength of the blue LED based on the xy chromaticity from the position in the lower right-upper left direction H1 in FIG.

  Further, as shown in FIG. 4, for example, the peak wavelength information input unit 5 includes an evaluation chart 31 and an illumination light analysis unit 32. The illumination light analysis unit 32 includes an illumination light type setting unit 33 and an observation result setting. The peak wavelength information input unit 5 may include a peak wavelength based on a patch observation result at a place where an image formed on the recording member is observed by the image recording unit 4. Get information. The illumination light analysis unit 32 determines the peak wavelength of the illumination light based on the observation result of the evaluation chart 31 by the user.

  The evaluation chart 31 is an evaluation chart adjusted for a white LED light source as shown in FIG. 5, for example. An evaluation chart 31 shown in FIG. 5 is a chart on which the reference patch Pk and the evaluation patches Ph1 to Ph3 are printed, and the reference patch Pk and the evaluation patches Ph1 to Ph3 are printed side by side in an arrangement state that can be easily compared. .

  In FIG. 5, the reference patch Pk is printed with a color material having a substantially uniform reflectance in a wavelength region where the peak wavelengths of the illumination lights L1 to L3 of the blue LED vary as shown in FIG. Ph1 to Ph3 are printed with color materials having a spectral reflectance equivalent to that of the reference patch Pk in the wavelength ranges corresponding to the spectral intensity distributions of the illumination lights L1 to L3, respectively. Therefore, under the illumination lights L1 to L3, the reference patch Pk and the evaluation patches Ph1 to Ph3 are perceived as the same color, respectively. For example, under the illumination light L2, the evaluation patch Ph1 has a blue component. Since the reflection is weak, it is yellow, and the evaluation patch Ph3 is perceived blue because the reflection of the blue component is strong.

  The illumination light type setting unit (illumination light type setting means) 33 is the same as the illumination light type setting unit 23 in FIG. 3, and the illumination light type setting part 23 observes the image formed on the recording member by the image recording unit 4. The type is set by the user, and the set illumination light type is output to the color material amount control unit 6 and the variation determination unit 35.

  The observation result setting unit (observation result setting means) 34 is in a place where the image formed on the recording member is observed by the image recording unit 4, and the observation result obtained by the user observing the evaluation chart 31 is set and input. The observed result is output to the variation determination unit 35. The observation result setting unit 34 is, for example, which of the evaluation patches Ph1 to Ph3 is perceived to be close to the reference patch Pk, and which is the closest evaluation patch Ph1 to Ph3 including the intermediate level. These are switches for the user to select and input.

  The variation determining unit (peak wavelength predicting unit) 35 determines the observation result variation within the type of illumination light set by the illumination light type setting unit 33 and predicts the peak wavelength. For example, when the illumination light type setting unit 23 sets the type of illumination light to a light bulb color or a white LED light source of daylight white, the peak wavelength of the blue LED is set based on the observation result set by the observation result setting unit 34. Predicting and outputting the predicted peak wavelength to the color material amount control unit 6. Specifically, the variation determination unit 35 predicts the peak wavelength of the blue LED from the relationship shown in FIG.

  As shown in FIG. 7, the color material amount control unit 6 includes a table storage unit 41, table correction units 42 a and 42 b, a table selection unit 43, and the like, and a peak input from the peak wavelength information input unit 5. Based on the wavelength information, the color material amount determined by the color material amount determination unit 3 is controlled.

  The table storage unit 41 stores a plurality of color material amount determination tables that indicate the correspondence between the amount of color material provided in the image recording unit 4 and the color of the image represented by the image data. The material amount determination table is output to the table correction units 42 a and 42 b or the table selection unit 43.

  The table storage unit 41 is a color material amount determination table for light sources with little variation in peak wavelength, for example, D65 light source, D50 light source, A light source, light bulb color, daylight white, daylight color, etc. For a color material amount determination table corresponding to a light source such as a fluorescent lamp, the stored color material amount determination table is output to the table selection unit 43, and a color material amount determination table for a light source having a large variation in peak wavelength, For example, for the color material amount determination table for a white LED light source such as a light bulb color or daylight white color, the stored color material amount determination table is output to the table correction units 42a and 42b, respectively. The table storage unit 41 stores the color material amount determination table as an LUT (Look Up Table). In the color material amount determination table, the image data is represented by sRGB data, and the sRGB grid The amount of the color material corresponding to the point is stored as a table.

  The table correction units 42 a and 42 b correct the color material amount determination table from the table storage unit 41 based on the peak wavelength information from the peak wavelength information input unit 5, and output it to the table selection unit 43. Specifically, the table correction units 42 a and 42 b store LUT correction data Δ corresponding to the peak wavelength information in advance in a built-in memory, and are based on the peak wavelength information input from the peak wavelength information input unit 5. Then, according to the color material amount determination table input from the table storage unit 41, the color material corresponding to the lattice point of the correction data Δ is corrected by the following equation (4).

Color material amount after correction (grid point coordinates)
= Amount of color material (grid point coordinates) + Δ (peak wavelength information, lattice point coordinates) (4)
The table selection unit 43 receives the color material amount determination table from the table storage unit 41 and the color material amount corrected by the table correction units 42 a and 42 b and the illumination light type from the peak wavelength information input unit 5. Based on the type of illumination light source (illumination light type) determined or set by the peak wavelength information input unit 5, the color material amount determination table input from the table storage unit 41 or the table correction units 42a and 42b is selected. And output to the color material amount determination unit 3. Specifically, the color material amount determination unit 3 converts image data obtained by the LUT into color material amounts, and the table selection unit 43 rewrites the LUT.

  Further, the color material amount control unit 6 is not limited to the above configuration, and may include a table storage unit 51, table correction units 52a and 52b, a table selection unit 53, and the like as shown in FIG. The color material amount determined by the color material amount determination unit 3 is controlled based on the peak wavelength information input from the peak wavelength information input unit 5.

  The table storage unit 51 stores a plurality of color material amount determination tables that indicate the correspondence between the amount of color material provided in the image recording unit 4 and the color of the image represented by the image data. The material amount determination table is output to the table correction units 52a and 52b or the table selection unit 53. The table storage unit 51 is a color material amount determination table for light sources with little variation in peak wavelength, for example, D65 light source, D50 light source, A light source, light bulb color, daylight white, daylight color, etc. For a color material amount determination table corresponding to a light source such as a fluorescent lamp, the stored color material amount determination table is output to the table selection unit 53, and a color material amount determination table for a light source having a large variation in peak wavelength, For example, for the color material amount determination table for the white LED light source such as the light bulb color and the daylight white color shown in FIG. 6, the stored color material amount determination table is output to the table correction units 52a and 52b, respectively. The table storage unit 51 stores the color material amount determination table as an LUT (Look Up Table). In the color material amount determination table, the image data is represented by sRGB data, and the sRGB grid The amount of the color material corresponding to the point is stored as a table.

  The table correction units 52 a and 52 b correct the color material amount determination table from the table storage unit 51 based on the peak wavelength information, and output the corrected color material amount determination table to the table selection unit 53. Specifically, in the case of the illumination light L1 and the illumination light L3 illustrated in FIG. 6, the table correction units 52a and 52b, for example, the peak wavelengths of the illumination light L1 and the illumination light L3, and the peak wavelength information (peak wavelength) of the illumination light. ), The color material amount determination table for the illumination light L1 and the illumination light L3 is interpolated by the following equation (5) to generate a color material amount determination table corresponding to the peak wavelength information, and the table selection unit 53 Output to.

Color material amount after correction (grid point coordinates)
= Coloring material amount for illumination light L1 (lattice coordinate) × ((peak wavelength of illumination light−peak wavelength of illumination light L3) / (peak wavelength of illumination light L1−peak wavelength of illumination light L3))
+ Coloring material amount for illumination light L3 (lattice point coordinates) × ((peak wavelength of illumination light−peak wavelength of illumination light L1) / (peak wavelength of illumination light L3−peak wavelength of illumination light L1)) ( 5)
Then, the table selection unit 53 is a color material input from the table storage unit 51 or the table correction units 52a and 52b based on the type (illumination light type) of the illumination light source determined or set by the peak wavelength information input unit 5. The amount table is selected and output to the color material amount determination unit 3. Specifically, the color material amount determination unit 3 converts the image data obtained by the LUT into the color material amount, and the table selection unit 53 rewrites the LUT.

  The image forming apparatus 1 includes a ROM, an EEPROM (Electrically Erasable and Programmable Read Only Memory), an EPROM, a flash memory, a flexible disk, a CD-ROM (Compact Disc Read Only Memory), a CD-RW (Compact Disc Rewritable), and a DVD. A ROM that reads an image forming program for executing the image forming method of the present invention recorded on a computer-readable recording medium such as a (Digital Versatile Disk), an SD (Secure Digital) card, or an MO (Magneto-Optical Disc) ROM And an image forming apparatus that executes an image forming method for forming an image with a color material amount suitable for a wavelength peak of illumination light described later. This image forming program is a computer-executable program written in a legacy programming language such as assembler, C, C ++, C #, Java (registered trademark) or an object-oriented programming language, and is stored in the recording medium. Can be distributed.

  Next, the operation of this embodiment will be described. The image forming apparatus 1 according to the present exemplary embodiment performs image formation in which color processing for determining a color material amount in consideration of variations in individual illumination light is performed.

  That is, when the image forming apparatus 1 forms an image on a recording medium, the image data input from the image input unit 2 is sent to the color material amount determination unit 3, and the color material amount determination unit 3 2 is determined based on the image data input from 2, the amount of the color material included in the image recording unit 4, that is, the color material amount suitable for forming an image of the color represented by the image data in the image recording unit 4. Then, the image recording unit 4 forms an image on the recording medium based on the determined color material amount.

  In the image forming process, the image forming apparatus 1 corrects the color material amount based on the peak wavelength of the illumination light at the place where the image formed on the recording medium is observed, as shown in FIG. Image formation.

  That is, prior to image formation, the image forming apparatus 1 sets the type of illumination light source at a place where an image formed on a recording medium is observed (step S101). The setting of the type of illumination light source (illumination light type) is, for example, the setting of the illumination light type using the peak wavelength information input unit 5 shown in FIGS. 2 to 4, and the spectral intensity distribution measurement unit 11 and the illumination Illumination light type setting using the light analysis unit 12, illumination light type setting using the tristimulus value measurement unit 21 and the illumination light analysis unit 22, or illumination light type setting using the evaluation chart 31 and the illumination light analysis unit 32 The illumination light type is set using any of the above.

  Next, the image forming apparatus 1 determines whether it is necessary to set peak wavelength information (step S102). Whether or not the peak wavelength information needs to be set is determined by the variation determination units 15, 25, and 35 of the illumination light analysis units 12, 22, and 32. As described above, the variation within the type is large. It is determined that it is necessary when the type of illumination light is set. For example, it is determined that peak wavelength information needs to be set when a light bulb color or a white white LED light source is set.

  When the illumination light analysis units 12, 22, and 32 determine that the peak wavelength information needs to be set, the variation determination units 15, 25, and 35 set the peak wavelength information to the color material amount control unit 6. Output (step S103). For example, when the type of illumination light is a white LED light source, the variation determining unit 15 determines and sets peak wavelength information based on the spectral intensity distribution measured by the spectral intensity distribution measuring unit 11 for the peak wavelength of the blue LED. The variation determination unit 25 determines and sets peak wavelength information based on the xy chromaticity obtained by converting the tristimulus value input from the tristimulus value measurement unit 21 by the chromaticity conversion unit 24. The variation determination unit 35 determines and sets peak wavelength information based on the observation result set by the user according to the observation result of the evaluation chart 31 and input from the observation result setting unit 34, and sets the color material amount control unit 6. Output to. In step S <b> 102, when the variation determination units 15, 25, and 35 determine that the peak wavelength information setting is unnecessary, the illumination light type determination unit 14, the illumination light type setting unit 23, and the illumination light type setting unit 33 The peak wavelength information of the illumination light type is output to the color material amount control unit 6.

  Next, the color material amount control unit 6 performs a color material amount control process for controlling the color material amount determined by the color material amount determination unit 3 (step S103). The color material amount control unit 6 controls the color material amount based on the type of illumination light set in the illumination light source type setting process and, if necessary, the peak wavelength information set in the peak wavelength information setting process. Do. The color material amount control unit 6 selects, for example, a color material amount determination table of image data and color material amount stored in advance according to the set type of illumination light, and further includes peak wavelength information. The amount of color material is controlled by correcting the color material amount determination table accordingly.

  Next, the image forming apparatus 1 performs image input processing by the image input unit 2 (step S105). As described above, the image input unit 2 is, for example, an image acquired by a digital still camera, a scanner, or the like taken from a digital still camera, a scanner, or a personal computer, a document creation software that operates on a personal computer, or a spreadsheet. Image data of a document created by application software such as software is acquired and output to the color material amount determination unit 3.

  Next, in the image forming apparatus 1, the color material amount determination unit 3 determines a color material amount suitable for recording (image formation) the color of the image of the image data input from the image input unit 2. A quantity determination process is performed (step S106). Based on the image data input from the image input unit 2 in the image input process, the color material amount determination unit 3 is an amount suitable for recording the color of the image represented by the image data of the color material included in the image recording unit 4 ( Color material amount) and a color material amount according to the color material amount input from the color material amount control unit 6 are determined.

  When the image forming apparatus 1 determines the color material amount, the image recording unit 4 records an image on a recording medium such as paper or film based on the color material amount determined in the color material amount determination process. (Step S107).

  As described above, the image forming apparatus 1 according to the present exemplary embodiment includes an image recording unit (image forming unit) that includes a predetermined number of color materials and forms an image on a recording medium using the color materials according to image data. ) 4, a color material amount determination part (color material amount determination means) 3 that determines the amount of the color material used by the image recording unit 4 based on the image data, and an image is formed using the color material. The peak wavelength information input unit (optical information acquisition means) 5 for acquiring the optical characteristic information of the illumination light at the place where the recording medium is observed, and the color material amount determination part 3 is determined based on the optical characteristic information A color material amount control unit (color material use amount adjusting means) 6 that adjusts the color material use amount.

  Therefore, it is possible to perform image formation in which color processing is performed in consideration of variations in individual illumination light when observing the formed image, and it is possible to form an image with an intended color appearance.

  The image forming apparatus 1 according to the present exemplary embodiment includes an image forming processing step that includes a predetermined number of color materials and forms an image on a recording medium using the color materials according to the image data. A color material amount determining process step of determining the usage amount of the color material included in the image forming process step and converting the image data into the image data, and forming the image using the color material. In addition, an optical information acquisition processing step of acquiring illumination light feature information of a place where the recording medium is observed, and use of the color material determined in the color material amount determination processing step based on the light feature information An image forming method including a color material usage amount adjustment processing step of adjusting the amount is executed.

  Therefore, it is possible to perform image formation in which color processing is performed in consideration of variations in individual illumination light when observing the formed image, and it is possible to form an image with an intended color appearance. Furthermore, the image forming apparatus 1 according to the present exemplary embodiment includes an image forming process in which a predetermined number of color materials are provided in a computer and an image is formed on a recording medium using the color materials according to image data. A color material amount determining process for determining the amount of the color material used in the image forming process based on the data and converting the image data into the image data; and forming the image using the color material. In addition, an optical information acquisition process for acquiring optical feature information of illumination light at a place where the recording medium is observed, and a usage amount of the color material determined in the color material amount determination process based on the optical feature information. An image forming program for executing a color material usage amount adjustment process to be adjusted is installed.

  Therefore, it is possible to perform image formation in which color processing is performed in consideration of variations in individual illumination light when observing the formed image, and it is possible to form an image with an intended color appearance.

  In the image forming apparatus 1 of the present embodiment, the peak wavelength information input unit 5 serving as the optical information acquisition unit acquires the peak wavelength information of the illumination light as the optical feature information.

  Therefore, it is possible to perform image formation in which color processing is performed in consideration of the peak wavelength of illumination light at the place where the image is observed, and an image with an intended color appearance can be formed.

  Furthermore, in the image forming apparatus 1 of the present embodiment, the peak wavelength information input unit 5 that is the optical information acquisition unit acquires the optical feature information of the illumination light including the LED.

  Therefore, the peak wavelength information can be acquired as the light feature information of the LED with many variations, and the perceived color under the proof light including the LED can be prevented from being different.

  Further, in the image forming apparatus 1 of the present embodiment, the peak wavelength information input unit 5 that is the optical information acquisition unit measures the spectral intensity distribution measurement unit (spectral intensity distribution measurement unit) 11 that measures the spectral intensity distribution of the illumination light. An illumination light type determination unit 14 that is an illumination light type determination unit that determines the type of illumination light based on the spectral intensity distribution measured by the spectral intensity distribution measurement unit 11, and a standard spectral intensity distribution storage unit 13. A variation determining unit (peak wavelength detecting means) 15 for detecting a peak wavelength based on the determined type of illumination light and the spectral intensity distribution measured by the spectral intensity distribution measuring unit 11 is provided.

  Therefore, it is possible to detect the peak wavelength of each illumination light when observing the formed image, and to perform image formation in which color processing is performed in consideration of variations in the illumination light. Can be formed.

  Furthermore, in the image forming apparatus 1 of the present embodiment, the peak wavelength information input unit 5 that is the optical information acquisition unit includes a tristimulus value measurement unit (chromaticity measurement unit) 21 that measures the chromaticity of the illumination light, and An illumination light type setting unit (illumination light type acquisition unit) 23 that acquires the type of illumination light, and a color that predicts a peak wavelength based on the type of illumination light and the chromaticity measured by the tristimulus value measurement unit 21 And a peak wavelength predicting means including a degree conversion unit 24 and a variation determination unit 25.

  Therefore, it is possible to predict the peak wavelength of individual illumination light when observing the formed image, and to perform image formation in which color processing is performed in consideration of variations in the illumination light. Can be formed.

  Further, in the image forming apparatus 1 according to the present embodiment, the peak wavelength information input unit 5 serving as the optical information acquisition unit is configured to input the observation result of the evaluation chart 31 having different colors at the peak wavelength of the illumination light. Based on the result setting unit (observation result setting means) 34, the illumination light type setting unit (illumination light type setting means) 33 to which the type of illumination light is set and input, the observation result and the type of illumination light And a variation determination unit (peak wavelength prediction means) 35 for predicting the peak wavelength of the illumination light.

  Therefore, the peak wavelength of each illumination light when observing the formed image can be easily and accurately predicted, and image formation can be performed with color processing taking into account variations in the illumination light. Colored images can be formed.

  The invention made by the present inventor has been specifically described based on the preferred embodiments. However, the present invention is not limited to that described in the above embodiments, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Image input part 3 Color material amount determination part 4 Image recording part 5 Peak wavelength information input part 6 Color material amount control part 11 Spectral intensity distribution measurement part 12 Illumination light analysis part 13 Standard spectral intensity distribution storage part 14 Illumination Light type determination unit 15 Variation determination unit 21 Tristimulus value measurement unit 22 Illumination light analysis unit 23 Illumination light type setting unit 24 Chromaticity conversion unit 25 Variation determination unit 31 Evaluation chart Pk reference patch Ph1 to Ph3 Evaluation patch 32 Illumination light analysis unit 33 Illumination light type setting unit 34 Observation result setting unit 35 Variation determination unit 41, 51 Table storage unit 42a, 42b, 52a, 52b Table correction unit 43, 53 Table selection unit L1-L3 Illumination light

JP 2007-159051 A

Claims (8)

An image forming unit that includes a predetermined number of color materials and forms an image on a recording medium using the color materials according to image data;
A color material amount determining means for determining a use amount of the color material included in the image forming means based on the image data;
Optical information acquisition means for acquiring optical feature information of illumination light at a place where the recording medium on which an image is formed using the color material is observed;
A color material use amount adjusting means for adjusting the use amount of the color material determined by the color material amount determining means based on the light feature information;
An image forming apparatus comprising: The optical information acquisition means
The image forming apparatus according to claim 1, wherein peak wavelength information of the illumination light is acquired as the light feature information. The optical information acquisition means
The image forming apparatus according to claim 1, wherein optical characteristic information of the illumination light including an LED is acquired. The optical information acquisition means
Spectral intensity distribution measuring means for measuring the spectral intensity distribution of the illumination light;
Illumination light type determination means for determining the type of the illumination light based on the spectral intensity distribution measured by the spectral intensity distribution measurement means;
A peak wavelength detecting means for detecting a peak wavelength based on the type of the illumination light determined by the illumination light type determining means and the spectral intensity distribution measured by the spectral intensity distribution measuring means;
The image forming apparatus according to claim 2, further comprising: The optical information acquisition means
Chromaticity measuring means for measuring the chromaticity of the illumination light;
Illumination light type acquisition means for acquiring the type of illumination light;
Peak wavelength predicting means for predicting a peak wavelength based on the type of illumination light and the chromaticity measured by the chromaticity measuring means;
The image forming apparatus according to claim 2, further comprising: The optical information acquisition means
Observation result setting means for setting and inputting observation results of evaluation charts having different colors at the peak wavelength of the illumination light,
Illumination light type setting means for setting and inputting the type of illumination light;
Peak wavelength prediction means for predicting a peak wavelength of the illumination light based on the observation result and the type of the illumination light,
The image forming apparatus according to claim 2, further comprising: An image forming process step that includes a predetermined number of color materials and forms an image on a recording medium using the color materials according to image data;
A color material amount determination processing step for determining a usage amount of the color material included in the image formation processing step based on image data and converting the image data into the image data;
An optical information acquisition processing step of acquiring optical feature information of illumination light at a place where the recording medium on which the image is formed is observed using the color material;
A color material usage amount adjustment processing step of adjusting the usage amount of the color material determined in the color material amount determination processing step based on the light feature information;
An image forming method characterized by comprising: On the computer,
An image forming process including a predetermined number of color materials and forming an image on a recording medium using the color materials according to image data;
A color material amount determination process for determining the amount of the color material used in the image forming process based on image data and converting the image data into the image data;
An optical information acquisition process for acquiring optical feature information of illumination light at a place where the recording medium on which the image is formed is observed using the color material;
Color material usage amount adjustment processing for adjusting the usage amount of the color material determined in the color material amount determination processing based on the light feature information;
An image forming program for executing

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