IMAGE QUALITY EVALUATION METHOD, IMAGE QUALITY EVALUATION APPARATUS, AND NON-TRANSITORY COMPUTER READABLE MEDIUM

An image quality evaluation method to be executed by an information processing apparatus includes: acquiring information about a step at a boundary portion between an image portion, which is formed using a recording material, and a base material portion, which is a ground of the image portion, and a gloss level of the image portion; and calculating an evaluation value of a relief feel on the basis of the acquired information about the step and the gloss level.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2022-005473 filed Jan. 18, 2022.

BACKGROUND

(i) Technical Field

The present disclosure relates to an image quality evaluation method, an image quality evaluation apparatus, and a non-transitory computer readable medium.

(ii) Related Art

A relief feel is one of defects caused when an image is formed using toners and pigment inks. The relief feel is had when a step at a boundary portion between a region (hereinafter also referred to as an “image portion”) in which toners or pigment inks are fixed and a region (hereinafter also referred to as a “base material portion”) in which toners or pigment inks are not fixed is visually detected. The step tends to be large and a relief feel is easily visually recognized in a region at an especially high concentration or a region in which toners or pigment inks in a plurality of colors are stacked. The relief feel is occasionally referred to as a “step feel” or an “uneven feel”.

An example of the related art is disclosed in Osamu IDE, Shigeki WASHINO, and Katsuhiko SUGAWARA “Optical Measurement Correlated with the Appearance of Image Height Difference in Glossy Prints”, Japan Hardcopy Fall Meeting, pp. 49-52 (2004).

SUMMARY

A relief feel is known to be correlated with the height and the inclination of a step at a boundary portion. However, it is difficult to quantitatively evaluate a relief feel through visual observation. While it is possible to measure the height of a step using a laser displacement gauge or a laser microscope, the evaluation of a relief feel is not determined on the basis of the height of a step alone. For example, a relief feel may be different depending on the difference in the gloss level of an image portion, even if the height of a step is the same.

Aspects of non-limiting embodiments of the present disclosure relate to enabling quantitative evaluation of a relief feel to be made in consideration of the gloss level of an image portion as well, unlike the case where a focus is placed on the height of a step at a boundary portion between the image portion and a base material portion alone.

According to an aspect of the present disclosure, there is provided an image quality evaluation method to be executed by an information processing apparatus, the image quality evaluation method including: acquiring information about a step at a boundary portion between an image portion, which is formed using a recording material, and a base material portion, which is a ground of the image portion, and a gloss level of the image portion; and calculating an evaluation value of a relief feel on a basis of the acquired information about the step and the gloss level.

DETAILED DESCRIPTION

<Configuration of Image Quality Evaluation Apparatus>

FIG.1illustrates an example of the hardware configuration of an image quality evaluation apparatus1that is used in various exemplary embodiments.

The image quality evaluation apparatus1illustrated inFIG.1is constituted as a device that is independent of a device that prints an image of a document etc. on a base material such as paper.

Hereinafter, the device that prints an image of a document etc. on a base material such as paper will also be referred to as a “printing device” or an “image forming device”. Examples of the image of a document etc. include images that include a text, an illustration, a table, a graph, a photograph, and a combination thereof.

The image quality evaluation apparatus1illustrated in

FIG.1includes a processor101that controls operation of the entire apparatus, a read only memory (ROM)102that stores a basic input output system (BIOS), etc., a random access memory (RAM)103that is used as a work area for the processor101, an auxiliary storage device104that stores programs and other data, a display105that displays evaluation results and information about operations, an operation reception device106that receives an operation by an operator, a light source107that generates illumination light, a specular reflected light receiver108that receives components of the illumination light specular reflection by a surface of printed matter to be evaluated, a surface height measurer109that measures the height of the surface of the printed matter to be evaluated, and a communication interface (IF)110that is used for communication with the outside.

The processor101and the various portions are connected to each other through a signal line111such as a bus.

The processor101, the ROM102, and the RAM103function as a so-called computer.

The processor101implements various functions through execution of the programs. For example, the processor101executes a function of calculating an evaluation value of a relief feel of printed matter to be evaluated etc. through execution of the programs.

A semiconductor memory or a hard disk device, for example, is used as the auxiliary storage device104. The auxiliary storage device104stores an operating system, firmware, application programs, etc., in addition to data measured by the specular reflected light receiver108and data measured by the surface height measurer109. Hereinafter, the operating system, the firmware, and the application programs will be collectively referred to as “programs”.

The display105is a liquid crystal display or an organic electro-luminescence (EL) display, for example, and is used to display a screen to be operated by a user as a person that makes an evaluation. The screen also displays evaluation results including calculated evaluation values.

While the display105is provided integrally with an apparatus body in the case of the present exemplary embodiment, the display105may be a monitor connected through the communication IF110, or may be a terminal apparatus connected through the communication IF110, e.g. a display of a printing device or a computer. The computer is not limited to a desktop computer, and may be a notebook computer or a smartphone.

The operation reception device106is constituted of a touch sensor disposed on the display105or a physical switch, button, etc. disposed on a housing of the device.

Alternatively, the operation reception device106may be a keyboard or a different input device connected to the image quality evaluation apparatus1, or may be a mouse or a different pointing device.

A device that integrates the display105and the operation reception device106is called a touch screen. The touch screen is used to receive an operation by the user on a key (hereinafter referred to as a “software key”) displayed in a software manner.

In the present exemplary embodiment, a parallel light source is used as the light source107. Therefore, light rays of illumination light that illuminates the surface of the printed matter are parallel to each other. The term “parallel” is used to mean a practically allowable range of parallelism. In the present exemplary embodiment, a white light source is used as the light source107.

In the present exemplary embodiment, the light source107is disposed at a position at which the light source107radiates illumination light at an angle of 60° with respect to the normal to a measurement surface of the printed matter to be evaluated.

The specular reflected light receiver108is a device that receives components of the illumination light specular reflection by the surface of the printed matter. A gloss meter that integrates the light source107and the specular reflected light receiver108may be used, for example.

The specular reflected light receiver108according to the present exemplary embodiment is provided at a position at which the specular reflected light receiver108receives components of the illumination light reflected in the direction at60° with respect to the normal to the measurement surface.

The light source107and the specular reflected light receiver108are disposed in the same plane. The light source107and the specular reflected light receiver108are an example of a second measurement unit.

While an angle of60° is used as the measurement angle in the present exemplary embodiment, a different angle may also be used. Angles of 20°, 45°, 75°, and 85° may also be used, for example.

The measurement angle may not be fixed, and may be switchable in accordance with the printed matter to be evaluated. The switching of the measurement angle may be executed on the basis of an operation by the user, or may be executed through control by the processor101in accordance with the amount of received light.

The surface height measurer109is a device that measures displacement of roughness on the surface of the printed matter with respect to the scanning direction. The surface height measurer109is an example of a first measurement unit.

The communication IF110is constituted of a module that conforms to a wired or wireless communication standard. An Ethernet (registered trademark) module, a Universal Serial Bus (USB) module, a wireless Local Area Network (LAN) module, etc. may be used for the communication IF110, for example.

<Sectional Structure of Region Portion to Be Evaluated and Relationship among Physical Amounts>

FIG.2schematically illustrates an example of the sectional structure of printed matter at a portion at which a relief feel tends to appear. InFIG.2, the inclination formed at an end portion of a recording material stacked on the surface of a base material is expressed as exaggerated.

In the case of the present exemplary embodiment, examples of the base material include paper, a film, and metal paper.

The paper is classified in accordance with the paper quality and the thickness.

Examples of the film include a polyethylene terephthalate (PET) film, a polypropylene (PP) film, and a polyvinyl chloride (PVC) film.

Examples of the metal paper include paper with a surface to which a paint containing a pearl pigment has been applied, paper with a surface to which an aluminum foil has been pasted, paper to which a PET film with a surface onto which an aluminum layer has been evaporated has been pasted, paper with a surface to which a holographic film has been pasted, and paper obtained by pasting thereto a PET film with a surface onto which an aluminum layer has been evaporated and thereafter removing only the film to leave only the evaporated layer on the surface thereof.

Examples of the recording material include toners and inks. The toners are used for electrophotography, and the inks are used for offset printing and inkjet printing.

In the example illustrated inFIG.2, a boundary portion between the surface of the base material and the recording material stacked on the surface of the base material is enlarged.

InFIG.2, a region in which the base material is exposed is referred to as a “base material portion”, and a region in which the surface of the base material is covered by the recording material is referred to as an “image portion”. InFIG.2, in addition, a connection portion with the base material portion formed at an end portion of the image portion is referred to as an “edge portion”. The thickness of the edge portion becomes thinner toward an outer edge portion.

In the case ofFIG.2, the thickness of the recording material stacked on the surface of the base material is represented as a step height ΔH1of a step between the surface of the base material and the upper surface of the image portion. The step height ΔH1is measured by the surface height measurer109. The step height ΔH1is an example of information about the step.

InFIG.2, light rays of the illumination light output from the light source107and light paths of light reflected by the base material portion and the image portion are also illustrated. Specular reflected components and diffuse reflected components are generated at any location. In the case ofFIG.2, specular reflected components from the surface region of the base material portion and specular reflected components from the surface region of the image portion excluding the edge portion are incident on the specular reflected light receiver108, and specular reflected components from the surface region of the edge portion are not incident on the specular reflected light receiver108.

The inclination angle of the edge portion may be calculated from the length of the edge portion in the X-axis direction and the step height ΔH1, for example. The inclination angle of the edge portion is larger as the step height ΔH1is higher if the length of the edge portion in the X-axis direction is the same, and is larger as the length of the edge portion in the X-axis direction is shorter if the step height ΔH1is the same. The inclination angle of the edge portion is also an example of information about the step.

FIG.3schematically illustrates another example of the sectional structure of printed matter at a portion at which a relief feel tends to appear. Portions inFIG.3corresponding to those inFIG.2are denoted by the corresponding reference numerals.

InFIG.3, a recording material A is stacked on the surface of the base material, and a different recording material B is stacked on a part of the surface of the recording material A.

In the case ofFIG.3, the specular reflected light receiver108receives specular reflected components from the surface region of the image portion A and specular reflected components from the upper surface of the image portion B, but specular reflected components from the surface region of the edge portion are not incident on the specular reflected light receiver108.

InFIG.3, a step height of a step at the boundary portion between the recording material A and the recording material B is represented as ΔH2. The height ΔH2is also measured by the surface height measurer109. The step height ΔH2is an example of information about the step.

FIG.4illustrates an example of an output profile of the specular reflected light receiver108. The vertical axis represents the luminance value of specular reflection, and the horizontal axis represents the position of the region portion that is used for evaluation.

The luminance value becomes larger toward the upper end, and becomes smaller toward the lower end. The position is given in the unit of microns (μm).

The output profile indicated inFIG.4corresponds to the sectional structures illustrated inFIGS.2and3. The luminance value of specular reflection measured by the specular reflected light receiver108is the largest at the upper portion of the image portion as the upper surface, the second largest at the base material portion and the portion of the lower image portion as the lower surface, and the smallest at the edge portion.

In the exemplary embodiments to be discussed later, the luminance value corresponding to the upper surface is used as a “gloss level” of the image portion, and the difference of the gloss level of the upper surface from the gloss level of the lower surface is used as a “gloss level difference”.

FIGS.5A and5Billustrate an example of measurement performed by the surface height measurer109.FIG.5Aillustrates an example of the sectional structure of a region portion to be measured, andFIG.5Billustrates an example of a measured waveform.

In the example illustrated inFIG.5A, the step height ΔH1of a step formed between the surface of the base material and the upper surface of the recording material is to be measured.

InFIG.5B, the vertical axis represents the height of a surface measured by the surface height measurer109, and the horizontal axis represents the position of the region portion that is used for evaluation. The height of a surface becomes higher toward the upper end, and becomes lower toward the lower end. The position is given in the unit of microns (μm).

As indicated inFIG.5B, the measured waveform appears as a waveform that reflects fine roughness on the surface. In the following description, the difference between the average height of the image portion and the average height of the base material portion is used as the step height ΔH1of the step between the base material portion and the image portion.

<Example of Printed Matter for Evaluation>

In the exemplary embodiments to be discussed later, dedicated printed matter is prepared for evaluation of a relief feel.

FIG.6illustrates an example of the layout of printed matter for evaluation. In the case ofFIG.6, patterns AR1to AR12of image data that tend to present a relief feel are disposed on the surface of a recording material. The patterns AR1to AR6are used to measure a step height ΔH, and the patterns AR7to AR12are used to measure a gloss level.

In the case ofFIG.6, the patterns that are used to measure a step height ΔH are linear patterns, and the patterns that are used to measure a gloss level are rectangular patterns.

The patterns AR1and AR7are patterns given at a tone level of 100% for each of cyan (C), magenta (M), yellow (Y), and black (K) in image data to be handled by a computer or other information processing apparatuses.

The patterns AR2and AR8are patterns given at a tone level of 100% for three colors, namely cyan (C), magenta (M), and yellow (Y).

The patterns AR3and AR9are patterns given at a tone level of 100% for two colors, namely cyan (C) and magenta (M).

The patterns AR4and AR10are patterns given at a tone level of 100% for two colors, namely cyan (C) and yellow (Y).

The patterns AR5and AR11are patterns given at a tone level of 100% for four colors, namely cyan (C), magenta (M), yellow (Y), and black (K).

The patterns AR6and AR12are patterns given at a tone level of 40% for three colors, namely cyan (C), magenta (M), and yellow (Y).

The film thickness of the image portion stacked on the surface of the base material becomes thicker as the number of colors of recording materials that are used for printing is increased if the tone level of the image data is the same. Thus, the film thickness of a pattern printed in two colors (hereinafter also referred to as a “secondary color”) is thicker than the film thickness of a pattern printed in a single color. Similarly, the film thickness of a pattern printed in three colors (hereinafter also referred to as a “tertiary color”) is thicker than the film thickness of a pattern printed in two colors, and the film thickness of a pattern printed in four colors (hereinafter also referred to as a “quaternary color”) is thicker than the film thickness of a pattern printed in three colors.

The film thickness of the image portion stacked on the surface of the recording material is proportional to the magnitude of the tone level of the image data corresponding to each color. Thus, the film thickness of a pattern printed at 80% is thicker than the film thickness of a pattern printed at 40%, and the film thickness of a pattern printed at 100% is thicker than the film thickness of a pattern printed at 80%.

In practice, however, the film thickness is non-linear with respect to an increase in the number of colors or an increase in the tone level because of constraints on the side of a printing device or an image forming device.

FIRST EXEMPLARY EMBODIMENT

FIG.7illustrates an example of the functional configuration of an image quality evaluation apparatus1according to a first exemplary embodiment. The functional components illustrated inFIG.7are implemented through execution of programs by the processor101(seeFIG.1).

The processor101according to the first exemplary embodiment functions as a step height acquisition unit201, a gloss level acquisition unit202, an evaluation value calculation unit203, and an evaluation value display unit204.

The step height acquisition unit201acquires the height of a step formed between the base material portion and the image portion from information on roughness on the surface of the printed matter measured by the surface height measurer109(seeFIG.1). In the case where the printed matter to be evaluated has the layout illustrated inFIG.6, the step height acquisition unit201acquires the height of a portion with the highest step height, that is, the height of the pattern AR1(seeFIG.6) corresponding to a quaternary color.

The gloss level acquisition unit202acquires the gloss level of the image portion, the step height of which has been acquired, or the gloss level of a different image portion printed under the same condition. In the present exemplary embodiment, the gloss level of the pattern AR7(seeFIG.6) corresponding to a quaternary color is acquired.

In the case where the printed matter to be evaluated has the layout, the gloss level acquisition unit202acquires the gloss level of the pattern AR1or the gloss level of the pattern AR7which is a different pattern printed under the same condition as the pattern AR1.

Being “printed under the same condition” means being printed on the same base material using recording materials in the same colors at the same tone level.

The evaluation value calculation unit203calculates an evaluation value of a relief feel on the basis of the acquired step height and gloss level. Specifically, the evaluation value calculation unit203calculates an evaluation value of a relief feel using the following formula.

In the formula, k1 is a coefficient. The value of k1 is given in advance.

The evaluation value display unit204displays the calculated evaluation value of the printed matter on the display105etc. The evaluation value may be used as an evaluation value for the specific printing device that is used to print the printed matter, or may be used as an evaluation value for the recording material that is used in the printing.

In the present exemplary embodiment, the evaluation value display unit204displays the calculated evaluation value in association with two types of curves that represent the degree of visible recognition of a relief feel.

One of the two types of curves is a curve that gives a lower limit value (hereinafter referred to as a “detection limit”) of the evaluation value that allows a person to notice a relief feel. The other one is a curve that gives an upper limit value (hereinafter referred to as an “allowable limit”) of the evaluation value that defines a relief feel that allows visual recognition.

FIG.8illustrates an example of evaluation values to be output. The vertical axis represents the gloss level, and the horizontal axis represents the step height. The gloss level becomes higher toward the upper end of the chart, and becomes lower toward the lower end. The step height becomes higher toward the right end of the chart, and becomes lower toward the left end. The horizontal axis is an example of a first axis, and the vertical axis is an example of a second axis.

The two-axis graph indicated inFIG.8indicates a curve that gives the detection limit of a relief feel and a curve that gives the allowable limit determined in terms of quality.

In the case ofFIG.8, the curve that gives the detection limit corresponds to an evaluation value of “1.5”, and the curve that gives the allowable limit corresponds to an evaluation value of “3.5”.

A relief feel is detected more easily as the step height is higher, even if the gloss level of the image portion is low. On the other hand, a relief feel is not detected easily when the step height is low, even if the gloss level of the image portion is high.

A relief feel is not detected for printed matter with an evaluation value positioned below the curve that gives the detection limit. In the case ofFIG.8, for example, a relief feel is not detected for printed matter with a calculated evaluation value of “1.2”.

On the contrary, a relief feel is visually recognized for printed matter with an evaluation value positioned in the range between the curve that gives the detection limit and the curve that gives the allowable limit, but the printed matter is allowable in terms of quality.

Printed matter with an evaluation value positioned above the curve that gives the allowable limit is printed matter with too conspicuous a relief feel to be allowed from the viewpoint of quality.

SECOND EXEMPLARY EMBODIMENT

FIG.9illustrates an example of the functional configuration of an image quality evaluation apparatus1according to a second exemplary embodiment. Portions inFIG.9corresponding to those inFIG.7are denoted by the corresponding reference numerals.

The functional components illustrated inFIG.9are also implemented through execution of programs by the processor101(seeFIG.1).

The processor101according to the second exemplary embodiment functions as a step inclination acquisition unit211, a gloss level acquisition unit202, an evaluation value calculation unit203A, and an evaluation value display unit204A.

The present exemplary embodiment is different from the first exemplary embodiment in that an evaluation value of a relief feel is calculated using the tilt of a step, that is, the inclination angle, in place of the height of a step.

In the present exemplary embodiment, to this end, the step inclination acquisition unit211is used in place of the step height acquisition unit201(seeFIG.7).

The step inclination acquisition unit211calculates an inclination angle on the basis of the length of an edge portion in the horizontal direction and the step height.

The evaluation value calculation unit203A calculates an evaluation value of a relief feel on the basis of the acquired step tilt and gloss level. Specifically, the evaluation value calculation unit203A calculates an evaluation value of a relief feel using the following formula.

In the formula, k11 is a coefficient. The value of k11 is given in advance.

The evaluation value display unit204A displays the calculated evaluation value of the printed matter on the display105etc.

Also in the present exemplary embodiment, the evaluation value display unit204A displays the calculated evaluation value in association with two types of curves that represent the degree of visible recognition of a relief feel.

Specifically, the evaluation value display unit204A defines the horizontal axis of the two-axis graph indicated inFIG.8as the step tilt, and displays a symbol that represents the printed matter to be evaluated and a calculated evaluation value on the two-axis graph.

THIRD EXEMPLARY EMBODIMENT

FIG.10illustrates an example of the functional configuration of an image quality evaluation apparatus1according to a third exemplary embodiment. Portions inFIG.10corresponding to those inFIG.7are denoted by the corresponding reference numerals.

The functional components illustrated inFIG.10are also implemented through execution of programs by the processor101(seeFIG.1).

The processor101according to the third exemplary embodiment functions as a step height acquisition unit201, a gloss level acquisition unit202, a gloss level difference acquisition unit212, an evaluation value calculation unit203B, and an evaluation value display unit204.

The present exemplary embodiment is different from the first exemplary embodiment in that the gloss level difference acquisition unit212calculates a difference between the gloss level of the image portion and the gloss level of the base material portion, that is, a gloss level difference, and gives the calculated gloss level difference to the evaluation value calculation unit203B. In the present exemplary embodiment, in other words, an evaluation value of a relief feel is calculated using the gloss level difference as well.

The evaluation value calculation unit203B calculates an evaluation value of a relief feel on the basis of the acquired step height, gloss level of the image portion, and gloss level difference. Specifically, the evaluation value calculation unit203B calculates an evaluation value of a relief feel using the following formula.

In the formula, k21 and k22 are each a coefficient. The values of k21 and k22 are given in advance.

The evaluation value calculation unit203B according to the present exemplary embodiment calculates an evaluation value using the gloss level difference between the base material portion and the image portion in a quaternary color as a constant.

In the case where the gloss level difference between the base material portion and the image portion is large, for example, the overall evaluation value has a large value, even if the evaluation value calculated using Formula 1 is small. This is because a relief feel is easily visually recognized when the difference between the gloss level of the base material portion and the gloss level of the image portion in a quaternary color is large.

In the case where the gloss level difference between the base material portion and the image portion is small, on the other hand, the evaluation value calculated using Formula 3 is close to the evaluation value calculated using Formula 1.

While an evaluation value is calculated using the step height in the present exemplary embodiment, an evaluation value may be calculated using the step tilt as in the second exemplary embodiment.

FOURTH EXEMPLARY EMBODIMENT

FIG.11illustrates an example of the functional configuration of an image quality evaluation apparatus1according to a fourth exemplary embodiment. Portions inFIG.11corresponding to those inFIG.10are denoted by the corresponding reference numerals.

The functional components illustrated inFIG.11are also implemented through execution of programs by the processor101(seeFIG.1).

The processor101according to the fourth exemplary embodiment functions as a step height acquisition unit201A, a gloss level acquisition unit202A, a gloss level difference acquisition unit212, an evaluation value calculation unit203C, and an evaluation value display unit204.

The present exemplary embodiment is different from the first exemplary embodiment in that an overall evaluation value is calculated by measuring a step height and a gloss level for a plurality of patterns with different numbers of stacked recording materials.

In the case ofFIG.11, the step height acquisition unit201A acquires a step height corresponding to each of a line printed in a secondary color, a line printed in a tertiary color, and a line printed in a quaternary color.

The line printed in a secondary color is a line corresponding to the pattern AR3or AR4(seeFIG.6). This line corresponds to a line formed by stacking recording materials corresponding to two types of colors given at a tone level of 100%. The step height corresponding to the line in a secondary color is roughly twice the step height corresponding to a line in a primary color.

The line printed in a tertiary color is a line corresponding to the pattern AR2(seeFIG.6). This line corresponds to a line formed by stacking recording materials corresponding to three types of colors given at a tone level of 100%. The step height corresponding to the line in a tertiary color is higher than that for a line in a secondary color, but is not necessarily roughly three times the step height corresponding to a line in a primary color because of constraints on the side of a printing device.

The gloss level acquisition unit202A acquires a gloss level of the pattern AR9or AR10corresponding to a secondary color, a gloss level of the pattern AR8corresponding to a tertiary color, a gloss level of the pattern AR7corresponding to a quaternary color, and a gloss level of the base material portion.

The evaluation value calculation unit203C calculates an evaluation value of a relief feel on the basis of the acquired three types of step heights, gloss levels of three types of image portions corresponding thereto, and gloss level difference between the image portion in a quaternary color and the base material portion. Specifically, the evaluation value calculation unit203C calculates an evaluation value of a relief feel using the following formula.

In the formula, k31, k32, k33, and k34 are each a coefficient. The values of k31, k32, k33, and k34 are given in advance.

The evaluation value calculation unit203C according to the present exemplary embodiment also calculates an evaluation value using the gloss level difference between the base material portion and the image portion in a quaternary color as a constant.

The evaluation value calculation unit203C according to the present exemplary embodiment is able to calculate an overall evaluation value, including an evaluation value for a secondary color, an evaluation value for a tertiary color, and an evaluation value for a quaternary color. While a plurality of steps and image portions with different heights are formed on the actual printed matter, it is possible to make an overall evaluation of a relief feel using Formula 4.

While an evaluation value is calculated using the step height in the present exemplary embodiment, an evaluation value may be calculated using the step tilt as in the second exemplary embodiment.

FIFTH EXEMPLARY EMBODIMENT

FIG.12illustrates an example of the functional configuration of an image quality evaluation apparatus1according to a fifth exemplary embodiment. Portions inFIG.12corresponding to those inFIG.11are denoted by the corresponding reference numerals.

The functional components illustrated inFIG.12are also implemented through execution of programs by the processor101(seeFIG.1).

The processor101according to the fifth exemplary embodiment functions as a step height acquisition unit201A, a gloss level acquisition unit202B, a gloss level difference acquisition unit212A, an evaluation value calculation unit203D, and an evaluation value display unit204.

The present exemplary embodiment is different from the fourth exemplary embodiment in that an overall evaluation value is calculated in consideration of the gloss level difference between an image portion for which the total amount of recording materials used is smaller and an image portion for which the total amount of recording materials used is larger.

In the case ofFIG.12, the gloss level acquisition unit202B acquires a gloss level of the pattern AR9or AR10(seeFIG.6) corresponding to a secondary color, a gloss level of the pattern AR8corresponding to a tertiary color, a gloss level of the pattern AR7corresponding to a quaternary color, and a gloss level of the base material portion, and additionally acquires a gloss level of the pattern AR12in a tertiary color with a small total amount of recording materials and a gloss level of the pattern AR11in a quaternary color with a large total amount of recording materials.

In the case ofFIG.12, the pattern AR12in a tertiary color with a small total amount of recording materials is a pattern output at a tone level for each color of 40%. On the other hand, the pattern AR11in a quaternary color with a large total amount of recording materials is a pattern output at a tone level for each color of 80%.

The evaluation value calculation unit203D calculates an evaluation value of a relief feel on the basis of the acquired three types of step heights, gloss levels of three types of image portions corresponding thereto, gloss level difference between the image portion in a quaternary color and the base material portion, and gloss level difference between the two image portions with different total amounts of recording materials used. Specifically, the evaluation value calculation unit203D calculates an evaluation value of a relief feel using the following formula.

Evaluation value =k41×step height×gloss level (secondary color)+k42×step height×gloss level (tertiary color)+k43×step height×gloss level (quaternary color)+k44×gloss level difference (between image portion at tone level of 100% and base material portion)+k45×gloss level difference (between image portion at tone level of 40% and image portion at tone level of 80%)   (Formula 5)

In the formula, k41, k42, k43, k44, and k45 are each a coefficient. The values of k41, k42, k43, k44, and k45 are given in advance.

The evaluation value calculation unit203D according to the present exemplary embodiment calculates an evaluation value using, as constants, the gloss level difference between the base material portion and the image portion at a tone level of 10% and additionally the gloss level difference between the image portion at a tone level of 40% and the image portion at a tone level of 80%. The image portion at a tone level of 40% is an example of a first image portion, and has a first thickness. The image portion at a tone level of 80% is an example of a second image portion, and has a second thickness (>first thickness).

The present exemplary embodiment is different from the fourth exemplary embodiment in that an evaluation value is calculated using the gloss level difference between the image portion at a tone level of 40% and the image portion at a tone level of 80%.

The evaluation value calculation unit203D according to the present exemplary embodiment is able to calculate an overall evaluation value, including not only the gloss level difference between the base material portion and the image portion but also the gloss level difference between two types of image portions at different tone levels. While a plurality of image portions with the same color tone but with different amounts of recording materials are formed on the actual printed matter, it is possible to make an overall evaluation of a relief feel using Formula 5.

While an evaluation value is calculated using the step height in the present exemplary embodiment, an evaluation value may be calculated using the step tilt as in the second exemplary embodiment.

OTHER EXEMPLARY EMBODIMENTS

(1) While exemplary embodiments of the present disclosure have been described above, the technical scope of the present disclosure is not limited to the exemplary embodiments discussed earlier. It is apparent from the following claims that a variety of modifications and improvements that may be made to the exemplary embodiments discussed earlier also fall within the technical scope of the present disclosure.

(2) While the image quality evaluation apparatus1including all of the light source107and the specular reflected light receiver108which are used to measure a gloss level, the surface height measurer109which measures roughness formed on the surface of printed matter, and the processor101which evaluates a relief feel has been described in the exemplary embodiments discussed earlier, the present disclosure may be implemented as a system that communicably connects a plurality of devices corresponding to the functions.

For example, the present disclosure may be implemented as an image quality evaluation system in which a gloss meter that includes the light source107and the specular reflected light receiver108which measure a gloss level, a device that includes the surface height measurer109, and an information processing apparatus that includes the processor101are connected to each other by way of a communication line or a network, or may be implemented as an image quality evaluation system in which the light source107and the specular reflected light receiver108which measure a gloss level, a device that includes the surface height measurer109, and an information processing apparatus that includes the processor101are connected to each other by way of a communication line or a network.

(3) While a white light source is used as the light source107(seeFIG.1) in the exemplary embodiments discussed earlier, the illumination light may be in any color. The illumination light is not limited to visible light, and may be infrared light, ultraviolet light, etc.

(4) While the base material portion is assumed to be a region in which the base material such as paper is exposed in the exemplary embodiments discussed earlier, the printing region that is used as the ground of the image portion may be a region in which a halftone pattern has been printed. The halftone pattern is a pattern that expresses concentration using dots of different sizes.