Image processing method and image processing apparatus that apply selected texture data to a target region

An image processing method of holding a plurality of texture data for applying a metal representation on an image. The method includes acquiring predetermined information concerning at least one of an observation distance as a distance between a print product on which a target region is printed and an observer observing the print product, a sheet on which the target region is printed, or an environment in which the print product is observed, selecting texture data from the plurality of texture data based on the acquired predetermined information, and applying, to the target region, the texture data selected in the selecting.

Cross Reference to Priority Application

This application claims the benefit of Japanese Patent Application No. 2021-126880, filed Aug. 2, 2021, which is hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an image processing method and an image processing apparatus.

Description of the Related Art

There is known a decoration technique of adding metal texture by adding texture data to an object to be decorated on digital data. In a decoration technique disclosed in Japanese Patent Laid-Open No. 2009-93287, information concerning a light source in a location where data decorated by texture data is observed is acquired first. Then, data having realistic texture is generated by performing, for the texture data, correction of faithfully reproducing metal reflection caused under the acquired light source.

However, the above conventional technique does not consider an observation distance when observing decorated data.FIG.1is a graph showing the frequency response characteristic of human vision in which the abscissa represents a frequency and the ordinate represents a contrast sensitivity. The frequency response characteristic of vision indicates the sensitivity characteristic representing a contrast visually recognized by a person at a given frequency. In the frequency response characteristic of vision, it is known that if the observation distance changes, the peak frequency of the contrast sensitivity changes. Referring toFIG.1, a solid line101and a broken line102represent the visual characteristics at different observation distances L1and L2(L1<L2), respectively. When comparing the contrasts respectively perceived at the two observation distances, the solid line101>the broken line102is obtained in a target region having a low-frequency domain103. The contrast when performing observation at the observation distance L1is perceived more strongly than the contrast when performing observation at the observation distance L2. On the other hand, the solid line101<the broken line102is obtained in a target region having a high-frequency domain104. Therefore, the contrast when performing observation at the observation distance L2is perceived more strongly than the contrast when performing observation at the observation distance L1. In this way, a problem that metal texture obtained by performing decoration is perceived differently depending on the observation distance arises.

SUMMARY OF THE INVENTION

The present invention provides a technique of suppressing deterioration in decoration effect by switching and using texture data to be used in accordance with the observation distance of decorated data.

According to an aspect, the present invention, provides an image processing method of holding a plurality of texture data for applying a metal representation on an image, comprising acquiring predetermined information concerning at least one of an observation distance as a distance between a print product on which a target region is printed and an observer observing the print product, a sheet on which the target region is printed, or an environment in which the print product is observed, selecting texture data from the plurality of texture data based on the acquired predetermined information, and applying, to the target region, the texture data selected in the selecting.

DESCRIPTION OF THE EMBODIMENTS

First Embodiment

The first embodiment will describe an example of creating decoration data that reproduces metal texture by adding texture data to a decoration region to which a metal representation is to be applied, and observing printed decoration data. An image processing apparatus according to the first embodiment sets a decoration region to which a metal representation is to be applied, and acquires at least two or more texture data as candidates to be added to the decoration region. Next, the image processing apparatus acquires predetermined information concerning the distance between printed decoration data and an observer who observes the printed decoration data, that is, an observation distance. Furthermore, the image processing apparatus selects such texture data that the skewness of a perceived image at the observation distance (to be described later) is high from the plurality of acquired texture data based on the acquired predetermined information concerning the observation distance, and uses it for decoration processing. Then, the image processing apparatus prints the obtained decoration data by an output apparatus. An arrangement and processing according to the first embodiment will be described below with reference toFIGS.2A to11B.

First, an image statistic having a correlation with the quality of metal texture in the first embodiment will be described with reference toFIGS.2A to2C.

An example of the characteristics of a metal substance is a strong metallic luster generated when free electrons in the substance and the electromagnetic wave of illumination light generate plasmon resonance. When a person perceives a metal texture, perception of a metallic luster (a metallic luster feeling) is important.

Perception of a metal texture by using a perception of luster is the same as in perception of texture of a substance projected on a two-dimensional image. The brain of a person can perceive the metal texture of a substance projected on an image by using, as a key, a statistic in the image having a high correlation with the above-described luster feeling. In recent years, a research result that the skewness of a luminance histogram contributes to the apparent luster feeling of a substance in an image has been reported. The skewness is a statistic representing the unevenness of the histogram in the image, and is calculated using a pixel count n in the image, pixel values xi (i=1, 2, . . . n), the average value x(−) of the pixel values, and a standard deviation s, given by:
skewness={n/(n−1)(n−2)}×Σ{((xi−x(−))/s}3(1)

Note that Σ represents the sum of values for i from 1 to n.

In the case of a bilaterally symmetric distribution, that is, a normal distribution, as shown inFIG.2B, the skewness is 0. To the contrary, in the case of a distribution that is long on the left side, as shown inFIG.2A, the skewness is a negative value. In the case of a distribution that is long on the right side, as shown inFIG.2C, the skewness is a positive value. In Isamu Motoyoshi, et al., “Image statistics and the perception of surface qualities” Nature 447.7141 (2007): 206-209, it is described that as the skewness of a luminance histogram in an image is a greater positive value (FIG.2C), a higher apparent luster feeling is perceived.

As described above, the luster feeling of the substance is a very important factor in perceiving a metal texture. That is, the use of such texture data that the skewness of the luminance histogram in the image is a greater positive value improves the apparent luster feeling, that is, the metal texture to be perceived.

FIG.3Ais a view showing the configuration of an image processing system to which an image processing apparatus30according to the first embodiment of the present invention is applied. As shown inFIG.3A, the image processing apparatus30according to the first embodiment is connected to a data server31and an output apparatus32.

The data server31holds texture data to be used by the user to perform decoration processing of reproducing metal texture. This texture data is input from the data server31to the image processing apparatus30.

The image processing apparatus30acquires data from the data server31, and then sends a control instruction to the output apparatus32and transfers necessary information and data. An operating system (OS) as well as a system program according to this embodiment, various application software programs, and parameter data necessary for various processes are stored and managed in a storage unit302. This storage unit302can be formed by a storage device represented by a hard disk or a flash ROM. A control unit301includes a CPU (Central Processing Unit)310(FIG.3B), and comprehensively controls processing in the image processing apparatus30by loading software stored in the storage unit302into a work memory304such as a RAM, and executing it. Note that the hardware arrangement and functional arrangement of the control unit301will be described later with reference toFIGS.3B and4, respectively. An operation unit (to also be referred to as a “UI” here after)303serving as a user interface performs processing associated with user input or display to a user with respect to execution of the processing in the image processing apparatus30, and includes an input device such as a keyboard and a pointing device and a display device, such as a display.

The output apparatus32is, for example, a print apparatus such as an inkjet printer, and includes a data transfer unit, a printer control unit, and a print unit. The output apparatus32prints, by the inkjet printing method, decoration data acquired from the image processing apparatus30. In this embodiment, a case in which the output apparatus32is an inkjet printer will be described, but the output apparatus32may be an electrophotographic printer. Alternatively, the output apparatus32may be a display or a projector.

FIG.3Bis a block diagram for explaining the hardware arrangement of the control unit301of the image processing apparatus30according to the embodiment.

The CPU310controls control processing by the control unit301by executing a program loaded into a RAM312corresponding to the above-described work memory304. A ROM311stores programs, various data, and the like. The RAM312provides a work area that stores various data, and the like, at the time of the operation of the CPU310, and is also used as a program loading area. An input/output interface (I/F)313controls an interface between the control unit301and the UI303or a network. An HDD (Hard Disk Drive)314also functions as the storage unit302shown inFIG.3A, and stores programs and various data.

FIG.4is a functional block diagram for explaining the functions of the image processing apparatus30according to the first embodiment. Note that each function shown inFIG.4is implemented when the above-described CPU310loads software stored in the storage unit302into the work memory304(RAM312) and executes it.

A target region setting unit401sets a region to which decoration processing of reproducing metal texture is applied. A texture data acquisition unit402acquires texture data input from the data server31to the image processing apparatus30. An observation distance acquisition unit403acquires information (to sometimes simply be referred to as an “observation distance” here after) concerning an observation distance when observing decoration data applied with the decoration processing. A texture data selection unit404selects, based on the observation distance acquired by the observation distance acquisition unit403, texture data to be used for the decoration processing from the texture data acquired by the texture data acquisition unit402. A texture data application unit405creates decoration data by arranging the texture data selected by the texture data selection unit404in the region set by the target region setting unit401. An output control unit406performs output control of causing the output apparatus32to output the thus created decoration data. Note that, in this example, these functions are implemented when the CPU310executes the programs, but some or all of the functions of the components of the functional blocks may be implemented by using dedicated circuits. Alternatively, some or all of the functions of the components of the functional blocks may be implemented by using a cloud computer.

FIG.5is a view showing an example of a UI screen when creating decoration data in the UI303of the image processing apparatus30according to the first embodiment.

The UI303according to the first embodiment includes a texture pattern display region505where texture patterns506selectable by the user are displayed and an edit data display region501where decoration data502is displayed. The user designates an application object503, in the decoration data502, to which gold and silver decoration is to be applied. Then, the desired texture pattern506can be selected from the texture pattern display region505, and the selected texture pattern can be applied to a decoration target region504in the application object503, thereby performing metal decoration. Furthermore, the UI303includes an observation distance input box507to observe printed decoration data. Furthermore, the UI303includes a dropdown list508for selecting a sheet size and a dropdown list509for selecting a print resolution, which are used to make print settings. Then, when a print button510is pressed, print processing of the decoration data502starts based on the print settings set in this screen. Note that the UI shown inFIG.5is merely an example, and the UI according to the embodiment is not limited to this.

FIG.6is a flowchart for explaining processing executed by the image processing apparatus30according to the first embodiment. Note that the embodiment describes an example in which the image processing apparatus30is outside the output apparatus32but the image processing apparatus30may be included in the output apparatus32. The processing illustrated by this flowchart is achieved when the CPU310executes a program loaded into the RAM312.

In step S601, the CPU310functions as the target region setting unit401to set a decoration target region (for example,503ofFIG.5) to which the texture data is to be applied and output it to the texture data application unit405. Note that an example of the decoration target region setting method is a method of setting, as an application object, an object designated by the user on the UI303, and setting text in the application object503as the decoration target region504, as shown inFIG.5. Note that the application object or the decoration target region need not be a text object, and may be, for example, a graphic object such as a circle or rhombus. Alternatively, a clip art such as a metal or a trophy may be possible. Instead of designating an object, the user may designate two points of the start point of a rectangle and its end point as a diagonal point on the decoration data, thereby setting a rectangular region surrounding the two points as the decoration target region. For example, the background surface of the decoration data may be set as the decoration target region.FIG.5shows an example of designating only one point of the application object503as an application object, but a plurality of objects may be designated.

The decoration target region may automatically be set instead of being set by the user. For example, when a gold and silver automatic decoration button (not shown) is pressed, a text region having a largest font size in the decoration data may automatically be set as the decoration target region. Alternatively, a region having high attractivity in the decoration data, detected by a known conspicuity detection technique, may be set as the decoration target region. This can create gold and silver decoration data by omitting the user's labor of selecting the decoration region. Even a user inexperience in design can effectively perform gold and silver decoration processing.

Next, the process advances to step S602and the CPU310functions as the texture data acquisition unit402to acquire at least two or more texture data input from the data server31to the image processing apparatus30. Then, the acquired texture data are output to the texture data selection unit404. The texture data are not limited to the texture patterns displayed in the texture pattern display region505.

FIGS.7A to7Care views for explaining texture pattern lists held in the data server31in correspondence with the texture pattern display region505shown inFIG.5.

For example, as shown inFIGS.7A to7C, texture pattern lists701to703respectively associated with the texture patterns displayed in the texture pattern display region505shown inFIG.5are held in the data server31. Then, in step S602, a plurality of texture data linked with the texture pattern selected by the user from the texture pattern display region505may be acquired. In the embodiment, the texture data are acquired directly from the data server31. However, these texture pattern lists may be saved in the storage unit302of the image processing apparatus30and then texture data may be acquired from the storage unit302.

Next, the process advances to step S603, and the CPU310functions as the observation distance acquisition unit403to acquire information concerning an observation distance at which the decoration data is observed and output it to the texture data selection unit404. With respect to this observation distance, for example, the information concerning the observation distance can be acquired based on a numerical value input by the user via the observation distance input box507shown inFIG.5. Instead of acquiring the information concerning the observation distance based on the numerical value input by the user, for example, as shown inFIG.7D, a dropdown list button710displaying items each for selecting an observation condition may be provided in the UI303and information concerning a corresponding observation distance may be acquired based on the item selected by the user.

FIG.7Dis a view showing an example of the dropdown list button for selecting an observation condition, which is displayed on the UI303of the image processing apparatus30according to the first embodiment.

In this case, the information concerning the observation distance is acquired based on the correspondences between observation distances and observation conditions held in advance in the storage unit302. For example, the observation distance may be set stepwise. For example, the observation distance is 30 cm for an observation condition of “leaflet”, is 1 m for an observation condition of “indoor display”, and is 3 m for an observation condition of “outdoor display”. Furthermore, it is generally known that a print sheet size and a distance (environment) at which a print product is observed are related to each other, and the observation distance may be simply set without designating it directly by the user. In this case, the correspondences between print sheet sizes and observation distances are held in advance in the storage unit302, and then the information concerning the observation distance is acquired based on the sheet size selected in the dropdown list508for selecting the print sheet size. For example, the length of the short or long side of the print sheet size may be acquired, and the correspondence between the sheet size and the observation distance may be decided so as to be proportional to the acquired length with reference to the length. An observation distance (for example, smaller than the A3 size) when observing a print product by holding it by a hand and an observation distance (for example, equal to or larger than the A3 size) when observing a print product by posting it on the wall may be set. Either case is possible as long as the information concerning the observation distance for the decoration data can be acquired. In this example, the form in which a value corresponding to the observation distance is finally acquired from the sheet size or the like input by the user has been explained. However, the present invention is not limited to this. That is, a form in which information indicating the sheet size or information indicating the length of the short or long side of the sheet size is acquired by accepting the user input but a value corresponding to the observation distance is not acquired based on the information may be possible. Note that, in this form, if the user inputs a sheet size, information indicating the length of the short or long side of the sheet size may be acquired based on the input sheet size. Then, when selecting texture data, as will be described below, the sheet size input by the user, the length of the short or long side of the sheet size input by the user, or the like, may be referred to, instead of the value corresponding to the observation distance. Note that in this embodiment, a custom size as a size arbitrarily decided by the user can be set as a sheet size. The image processing apparatus30acquires the custom size when the user decides/inputs the length of the short side and/or the long side of the size. On the other hand, in the case of a regular size such as the A4 size, a program that displays the UI303recognizes, in advance, the length of the short side and/or the long size of the size, and the image processing apparatus30thus acquires the information recognized by the program.

Next, the process advances to step S604, and the CPU310functions as the texture data selection unit404to simulate perceived luminance contrast data (to be described later) based on the information concerning the observation distance acquired by the observation distance acquisition unit403with respect to the plurality of texture data acquired by the texture data acquisition unit402. The skewness of a luminance histogram in the thus simulated perceived luminance contrast data is calculated. Then, texture data presenting high skewness is selected from the plurality of texture data and the selected texture data is output to the texture data application unit405.

The perceived luminance contrast data is data obtained by simulating luminance contrast data perceived by a person in consideration of the frequency response characteristic of vision.

First, the texture data is converted into luminance contrast data. If the input texture data is RGB data, it can be converted into YCbCr data using equations (2) to (4) below. The conversion formulas from RGB data into YCbCr data are merely examples and other conversion formulas may be used.
Y=0.299·R30 0.587·G+0.114·B(2)
Cb=−0.169·R−0.331·G+0.5·B(3)
Cr=0.5·R−0.419·G−0.081·B(4)

Subsequently, a method of simulating the perceived luminance contrast data by applying, to the luminance contrast data, the frequency response characteristic of vision corresponding to the observation distance will be described.

As the frequency response characteristic (VTF) of vision, for example, the Dooley's approximation given by equation (5) below can be used.
VTF=5.05×exp(−0.138×πLf/180)×(1−exp(−0.1×πLf/180))  (5)

where L represents the observation distance [mm] and f represents the frequency [cycles/mm]. In step S604, the observation distance acquired in step S603is used. The example of using the Dooley's approximation has been explained above but the frequency response characteristic of vision is not limited to this. Any sensitivity characteristic indicating a contrast visually recognized by a person in accordance with the frequency is possible.

Then, the luminance contrast data is converted into frequency data. Conversion into frequency data can be performed using a known technique such as FFT (Fast Fourier Transform). A frequency included in the data can be calculated based on the pixel count of the texture data and a size after printing. For example, the highest frequency f [cycles/mm] included in the texture data of a size s [mm] after printing can be calculated by equation (6) when n [pix ] represents the pixel count of the texture data.
f=n/2s(6)

Each frequency in the texture data calculated based on the pixel count of the texture data and the size after printing, as described above, is multiplied by the frequency response characteristic of vision. Then, by inversely converting the obtained frequency data into the luminance contrast data, the perceived luminance contrast data obtained by simulating the contrast perceived by a person can be calculated. Note that in the first embodiment, as an example, a case in which the texture data is a rectangle is assumed. However, the texture data is not always a rectangle. In this case, in conformance with the shape of the texture data, the frequency in the texture data may be calculated with reference to, for example, the width or the height. Alternatively, the frequency in the texture data may be calculated with reference to the average value of the height and the width.

FIG.8is a flowchart for explaining details of the processing in step S604ofFIG.6.

In step S801, the CPU310calculates luminance contrast data using equations (2) to (4) with respect to the texture data acquired in step S602. The process advances to step S802and the CPU310simulates the perceived luminance contrast data based on the observation distance acquired by the observation distance acquisition unit403with respect to the luminance contrast data calculated in step S801. The process advances to step S803and the CPU310calculates skewness using equation (1) with respect to the perceived luminance contrast data calculated in step S802. The process advances to step S804and the CPU310determines whether the processing has been applied to all the texture data acquired in step S602. If the processing has ended for all the texture data, the process advances to step S805. Otherwise, the process returns to step S801to repeat the above-described processing. Then, in step S805, the CPU310selects the texture data to be used for gold and silver decoration processing based on the skewness calculated in step S803. At this time, for example, the texture data presenting the highest skewness calculated in step S803may be selected.

In the texture data lists shown inFIGS.7A to7C, the texture data as a reference is decided in advance, and the texture data presenting the skewness higher than the skewness calculated from the reference texture data may be selected. An example of the reference texture data is the texture data selected by the user in the texture pattern display region505. If the observation distance is changed after gold and silver decoration is applied, the texture data set before the observation distance is changed may be set as the reference texture data.

If a plurality of texture data are candidates, the texture data with average luminance closest to that of the reference texture data may be selected or the texture data with a hue or chroma closest to that of the reference texture data may be selected. That is, the texture data presenting the skewness higher than that calculated from the reference texture data need only be selected. As described above, by selecting the texture data presenting the high skewness on perceived data obtained by simulating the actual appearance, the texture data with high metal texture at the assumed observation distance can be selected.

The first embodiment has explained the example of executing steps S801to S805after the acquisition of the information concerning the observation distance in step S603, and selecting the texture data. The embodiment, however, is not limited to this. For example, the processes in steps S801to S805may be applied in advance to each held texture data in accordance with the assumed observation distance. That is, an appropriate correspondence table of texture data according to the observation distances may be held in advance in the storage unit302, and the appropriate texture data may be selected in accordance with the observation distance acquired in step S603with reference to the correspondence table. This can omit part of the processing of selecting the texture data, thereby shortening the processing time. Then, as described above, the appropriate texture data may be selected in accordance with, not the value indicating the observation distance, but the sheet size input by the user or the length of the short or long side of the sheet size input by the user. Note that, for example, if the long side of the sheet size input by the user is long, the observation distance is considered to be long, and if the long side of the sheet size input by the user is short, the observation distance is considered to be short.

Referring back toFIG.6, in step S605, the CPU310functions as the texture data application unit405to apply the texture data selected by the texture data selection unit404to the decoration target region set by the target region setting unit401, thereby creating decoration data having undergone gold and silver decoration. Then, the decoration data is output to the output control unit406.

FIG.9is a flowchart for explaining details of the texture data application processing in step S605.

In step S901, the CPU310determines whether the size of the texture data selected in step S604is equal to or larger than the size of the application object. If it is determined that the size of the texture data is equal to or larger than the size of the application object, the process advances to step S903. Otherwise, the process advances to step S902. The comparison between the sizes indicates comparison between each of the long and short sides of the texture data and each of the long and short sides of the application object. If the size of the texture data is smaller than that of the application object with respect to at least one of the long and short sides, the process advances to step S902.

In step S902, the CPU310tiles the texture data1000, as shown inFIG.10A. This tiling processing is performed until the size of each of the short and long sides of the tiled texture data becomes equal to or larger than the size of each of the short and long sides of the application object503. When performing the tiling processing, tiling may be performed so that the texture data do not overlap each other or the texture data are allowed to overlap each other to some extent.

In step S903, the CPU310aligns the texture data acquired in step S901or S902with the application object, and then clips the texture data in conformance with the shape of the decoration target region. The thus clipped texture data is superimposed on the decoration target region or the decoration target region is replaced by the clipped texture data, thereby applying gold and silver decoration.

As an example of the method of aligning the texture data with the application object is a method of performing alignment with reference to the upper left positions of the texture data and the application object. Alignment need not be performed with reference to the upper left positions, as a matter of course. That is, alignment need only be performed so that the texture data exists in the entire decoration target region. Then, the aligned texture data is clipped in conformance with the shape of the decoration target region. As the clipping method, for example, a mask image of the decoration target region may be generated using RGB values as thresholds, and applied to the texture data, thereby performing clipping. Furthermore, if the application object is data in the SVG format, the SVG clipPath function may be used. That is, any method can be used as long as the texture data can be clipped in conformance with the shape of the decoration target region.

In the first embodiment, the example in which the texture data are tiled and used without enlargement or reduction has been explained. However, if a resolution is assumed when designing the texture data, and the resolution is different from that when creating decoration data, the texture data may be enlarged or reduced. For example, if the texture data is created by assuming 300 dpi (dots/inch) and the decoration data is created at 600 dpi, the texture data is enlarged to four times in area, and, then, steps S901to S903described above are executed. This can adjust the appearance of the texture data on the decoration data to the appearance when the texture data is created.

Referring back toFIG.6, in step S606, the CPU310functions as the output control unit406to perform print control processing for outputting the decoration data created in step S605from the output apparatus32.

FIG.10Bis a flowchart for explaining the decoration data print processing in step S606.

In step S1001, the CPU310inputs an RGB image of the decoration data. The process advances to step S1002, and the CPU310performs color correction processing of converting the RGB color of the decoration data into RGB values suitable for printing. As the color correction processing, known preferable processing may be used. The process advances to step S1003, and the CPU310performs color separation processing of converting the RGB values into use amounts of inks used by the printheads of the output apparatus32. As the method of the color separation processing, known preferable processing may be used. As assumed inks, color separation processing into CMYK inks or color separation processing into inks including spot color ink such as metallic ink may be possible.

Next, the process advances to step S1004, and the CPU310performs quantization processing of performing conversion into the presence/absence of a dot to be actually printed by the printhead corresponding to each color. As the quantization processing, any method such as known error diffusion processing or dither processing may be used. If the thus quantized dot data is transmitted to the printheads, and preparation of dot data for one scan is complete, actual printing is executed on a sheet using the printheads. In step S1005, the CPU310determines whether print processing is complete for all the pixels of the input decoration data. If the print processing is complete, the process ends. Otherwise, the process returns to step S1001and the remaining decoration data is processed. After that, by repeatedly performing the processes in step S1001to S1005until the decoration data print processing ends, the decoration data print processing is performed by the image processing apparatus30.

According to the first embodiment described above, information concerning an observation distance when observing data having undergone gold and silver decoration is acquired, and texture data presenting high skewness at the observation distance is selected from a plurality of acquired texture data. This can use the texture data having a high luster feeling at the observation distance. That is, it is possible to reproduce metal texture corresponding to the observation distance, thereby suppressing deterioration in decoration effect.

First Modification of First Embodiment

In the above-described first embodiment, the arrangement in which the functional modules401to406shown inFIG.4are implemented in the image processing apparatus30has been exemplified. However, some of the functions of the functional modules401to406may be implemented outside the image processing apparatus, for example, in a processing server110shown inFIG.11A.

FIG.11Ais a view showing the configuration of an image processing system according to the first modification of the first embodiment of the present invention.

Examples of the processing server110are an on-premise physical server and a virtual server configured on a cloud service. The data server31may be included in the processing server110, as a matter of course.

An example when some of the components of the functional blocks are implemented in the processing server110will be described with reference toFIG.11B.

FIG.11Bis a functional block diagram for explaining the functions of the processing server110and the image processing apparatus30according to the first modification of the first embodiment. Note that the same reference numerals as inFIG.4described above denote the same parts and a description thereof will be omitted.

In this image processing system, the target region setting unit401, the observation distance acquisition unit403, and the output control unit406exist on the image processing apparatus30, and the texture data acquisition unit402, the texture data selection unit404, and the texture data application unit405exist on the processing server110.

In this image processing system, in step S602ofFIG.6described above, for example, the texture data acquisition unit402of the processing server110receives the information of the texture pattern selected in the texture pattern display region505, thereby acquiring the corresponding texture data. In steps S601and S603, the acquired decoration target region and the information concerning the observation distance are output to the texture data application unit405and the texture data selection unit404on the processing server110, respectively, and the processing server110executes steps S604and S605. In step S606, the output control unit406of the image processing apparatus30receives the decoration data created in step S605, and the image processing apparatus30performs print control.

The method of implementing the components of the functional blocks in the image processing apparatus30and the processing server110is not limited to this. The texture data acquisition unit402and the texture data selection unit404may be implemented on the image processing apparatus30, and the selected texture data may be output to the texture data application unit405of the processing server110.

According to the first modification of the first embodiment, if the capacity of the decoration data is very large (for example, the decoration data is of the A0 size), some of the components of the functional blocks with high processing loads are implemented in the processing server having processing capability higher than the image processing apparatus, thereby making it possible to speed up the processing. In addition, since only the functional blocks with low processing loads can be implemented in the image processing apparatus30, the processing capability of the image processing apparatus30may be made lower than that of the processing server110. That is, an operation using the image processing apparatus such as a smartphone or a tablet terminal can be performed, thereby facilitating creation of decoration data by a remote operation.

Second Modification of First Embodiment

The above embodiment has explained the example of creating decoration data to be output to the inkjet printer. To the contrary, when the created decoration data is displayed, that is, preview-displayed on the display, the texture data may be switched in accordance with the observation distance set in the observation distance input box507. In addition to the observation distance of the printed decoration data set in the observation distance input box507, an observation distance when observing the preview display displayed on the display may be set. In this case, with respect to the decoration data for preview display, the texture data may be switched in accordance with the set observation distance for the preview display. This makes it possible to create decoration data while confirming metal texture reproduced in the texture data after printing.

As the texture data used for decoration data for preview display, texture data having a resolution different from that of the decoration data to be printed may be used. For example, when comparing the resolution of the display for performing preview display with the resolution of the output apparatus such as an inkjet printer, the resolution of the display is often lower. Therefore, with respect to the decoration data for preview display, even if texture data having a resolution lower than that of the texture data used for decoration data to be printed is used, it may be possible to provide sufficient image quality. As described above, by switching the texture data to be used at the time of printing or previewing, the processing load is reduced, thereby making it possible to speed up the processing. Furthermore, by switching the decoration data at the time of previewing or printing, metal texture of the decoration region seen at the time of preview display can be made close to the impression given when seeing the actual print product at an appropriate observation distance.

Second Embodiment

In the above-described first embodiment, appropriate texture data is selected from a plurality of acquire texture data in accordance with an observation distance, and used for decoration processing. To the contrary, an image processing apparatus according to the second embodiment acquires an illumination pattern in addition to texture data, composites the acquired illumination pattern with the texture data, and then uses the thus obtained data for decoration processing. The obtained decoration data is output to an output apparatus. An arrangement and processing according to the second embodiment will be described with reference toFIGS.12to16. Note that a system configuration, the hardware arrangement of an image processing apparatus30, and the like according to the second embodiment are the same as those in the above-described first embodiment and a description thereof will be omitted.

An illumination pattern indicates a gradation pattern obtained by simulating the intensity distribution of a reflected light component when texture data is illuminated.

FIG.12is a view for explaining illumination patterns according to the second embodiment of the present invention.

A region represented by white indicates a region that is illuminated to reflect strongly, and a region represented by black indicates a shadow region. For example, an illumination pattern1201is an illumination pattern assuming a status in which it is illuminated from the upper left side. An illumination pattern1202is a pattern in which reflected light in the vertical direction is expressed strongly, and recalls a status in which an object having a columnar shape is illuminated. An illumination pattern1203includes two strong reflected light components and recalls a shape more complicated than the illumination pattern1202. The variations of the illumination patterns are not limited to them. By assuming that the illumination pattern is applied to decoration data, variations may be held to be switched in accordance with the shape of an application object. When, for example, decoration processing is performed for text, if a strong reflection component is composited near a character outline, recognizability may deteriorate, and thus an illumination pattern in which the brightness near the character outline is suppressed may be held. By making a contrivance to the illumination pattern, the luster feeling by reflected light can be reproduced without degrading the recognizability of a decoration target region. The form of the illumination pattern may be vector data or raster data.

In the second embodiment, the above-described illumination pattern is held in addition to texture data, and composited with the texture data in processing (to be described later), thereby making it possible to reproduce reflected light in accordance with illumination light and a virtual shape. That is, it is possible to reproduce more realistic metal texture. The configuration of an image processing system to which the image processing apparatus according to the second embodiment is applied is the same as that according to the above-described first embodiment, and a description thereof will be omitted.

FIG.13is a functional block diagram for explaining the functions of the image processing apparatus30according to the second embodiment of the present invention. The functions of a target region setting unit401, a texture data acquisition unit402, an observation distance acquisition unit403, a texture data selection unit404, and an output control unit406according to the second embodiment are the same as those in the above-described first embodiment and a description thereof will be omitted. Only parts different fromFIG.4will be described below.

An illumination pattern acquisition unit1301acquires an illumination pattern input from a data server31to the image processing apparatus30. A texture data application unit1302composites the illumination pattern with texture data selected by the texture data selection unit404and arranges the thus obtained data in an application region, thereby creating decoration data.

FIG.14is a flowchart for explaining processing executed by the image processing apparatus30according to the second embodiment. In steps S1401, S1402, S1404, S1405, and S1407, the same processes as those in steps S601, S602, S603, S604, and S606ofFIG.6in the first embodiment are executed, respectively, and a description thereof will be omitted. Only portions different from the flowchart shown inFIG.6will be described.

In step S1403, a CPU310functions as the illumination pattern acquisition unit1301to acquire an illumination pattern input from the data server31to the image processing apparatus30. Then, the acquired illumination pattern is output to the texture data application unit1302.

As for this illumination pattern, for example, an illumination pattern selection list shown inFIG.15Amay be provided on a UI303, and an illumination pattern selected by the user may be acquired. Alternatively, an illumination pattern setting bar (not shown) for designating start and end points and intensity values at the start and end points may be provided to dynamically generate a gradation pattern, and the gradation pattern may be used as the illumination pattern. By dynamically generating a pattern, fine control can be executed in accordance with the preference of the user. Alternatively, without providing the illumination pattern selection list or the illumination pattern setting bar on the UI303, an illumination pattern associated with each of the texture data displayed in the texture pattern display region (or texture pattern selection list)505may be acquired. This can automatically select an illumination pattern appropriate for texture data without requiring the user's labor of selecting the illumination pattern.

Note that the second embodiment has explained the example of acquiring the illumination pattern directly from the data server31, but an illumination pattern stored in advance in a storage unit302may be acquired, as a matter of course.

In step S1406, the CPU310functions as the texture data application unit1302to composite the illumination pattern acquired by the illumination pattern acquisition unit1301with the texture data selected by the texture data selection unit404. The thus composited texture data is applied to the decoration target region set by the target region setting unit401, thereby creating decoration data having undergone gold and silver decoration. Then, the decoration data is output to the output control unit406.

FIG.15Bis a flowchart for explaining details of the texture data application processing in step S1406. In steps S1501, S1502, and S1504, the same processes as those in steps S901, S902, and S903in the first embodiment are executed and a description thereof will be omitted. Only portions different from the flowchart shown inFIG.9will be described below.

In step S1503, the illumination pattern is composited with the texture data acquired in step S1501or S1502.

FIG.16is a view for explaining an outline of the processing in step S1503.

First, magnification processing is applied to the illumination pattern in accordance with the size of the texture data. For the magnification processing, a known technique can be used, and an example is magnification processing using bicubic interpolation or bilinear interpolation. When the illumination pattern is magnified in accordance with the size of the texture data and used, it is possible to control the luster feeling in accordance with the size of the texture data.

Next, composition processing is performed by aligning the texture data with the illumination pattern applied with the magnification processing. As the processing of performing alignment, the method described in step S903ofFIG.9can be used. As the composition processing, known layer composition processing can be used. For example, the texture data and the illumination pattern can be composited by layer composition processing such as soft light or an overlay. As described above, the processing of the image processing apparatus30according to the second embodiment is performed.

As described above, according to the second embodiment, by acquiring the illumination pattern and compositing it with the selected texture data, it is possible to reproduce a high specular reflection characteristic as the characteristic of metal. That is, it is possible to create decoration data that reproduces more realistic metal texture. Furthermore, by separately holding the texture data and the illumination pattern, magnifying the illumination pattern in accordance with the size of the decoration target region, and then compositing the illumination pattern with the texture data, it is possible to reproduce metal texture having almost the same impression to a decoration target region of a different size.

Third Embodiment

In the above-described embodiment, appropriate texture data is selected from a plurality of acquired texture data in accordance with an observation distance and used for decoration processing. To the contrary, an image processing apparatus according to the third embodiment acquires one texture data, corrects it in accordance with the observation distance of decoration data, and uses the thus obtained data for decoration processing. The obtained decoration data is output to an output apparatus. An arrangement and processing according to the third embodiment will be described below with reference toFIGS.17to20. Note that the configuration of an image processing system to which the image processing apparatus according to the third embodiment is applied is the same as that according to the first embodiment and a description thereof will be omitted.

FIG.17is a functional block diagram for explaining the functions of an image processing apparatus30according to the third embodiment. Note that, inFIG.17, the same reference numerals as inFIG.4described above denote the same parts and a description thereof will be omitted. Only parts different fromFIG.4will be described below.

A texture data correction unit1701corrects, based on information concerning an observation distance acquired by an observation distance acquisition unit403, texture data acquired by a texture data acquisition unit402so that metal texture perceived when an observer observes, at the observation distance, a print product on which the texture data is printed becomes high, when the distance between the print product and the observer observing the print product is the observation distance.

FIG.18is a flowchart for explaining processing executed by the image processing apparatus30according to the third embodiment. Note that, in steps S1801, S1803, S1805, and S1806ofFIG.18, the same processes as those in steps S601, S603, S605, and S606ofFIG.6in the first embodiment are executed and a description thereof will be omitted. Only portions different from the flowchart shown inFIG.6will be described below.

In step S1802, a CPU310functions as the texture data acquisition unit402to acquire texture data input from a data server31to the image processing apparatus30. Then, the acquired texture data is output to the texture data correction unit1701. More specifically, the user acquires one texture data associated with a texture pattern selected in the texture pattern display region (or texture pattern selection list)505on a UI303inFIG.5. In the third embodiment, an example in which texture data is acquired directly from the data server31has been explained. However, texture data acquired in advance in a storage unit302may be acquired, as a matter of course.

In step S1804, the CPU310functions as the texture data correction unit1701to correct the texture data acquired by the texture data acquisition unit402so that the skewness of a luminance histogram in perceived luminance contrast data becomes high, based on the information concerning the observation distance acquired by the observation distance acquisition unit403. Then, in step S1805, the CPU310outputs the corrected texture data to a texture data application unit405.

FIG.19is a flowchart for explaining an example of texture data correction processing according to the observation distance in step S1804. In steps S1901and S1902, the same processes as those in steps S801and S802ofFIG.8described above are executed and a description thereof will be omitted.

In step S1903, the CPU310calculates a representative value in the perceived luminance contrast data calculated in step S1901. The representative value is, for example, a mode or an average value.

FIG.20is a graph for explaining an example of calculating the representative value according to the third embodiment.

The representative value is a mode2001. A histogram2002indicates the histogram of the perceived luminance contrast data.

In step S1904, the CPU310corrects a pixel value equal to or greater than the mode2001(representative value) calculated in step S1903. More specifically, correction is performed so that the mode2001and a maximum dynamic range2004of the histogram2002of the perceived luminance contrast data become larger. Note that the maximum dynamic range2004is a range of the histogram of the mode2001or more. For example, correction is performed so that the maximum value of the perceived luminance contrast data is the maximum value that can be taken by the perceived luminance contrast data. This correction method may multiply, by a positive coefficient, a pixel value equal to or greater than the mode included in the perceived luminance contrast data. Alternatively, known histogram planarization processing may be used to perform processing for the pixel value included in the dynamic range2004so that the dynamic range becomes large.

A histogram2003shown inFIG.20is an example of a histogram after correction. In the histogram2003, a maximum dynamic range2005with respect to the mode (representative value)2001is larger than the dynamic range2004before correction. That is, the unevenness of the histogram is larger and it can thus be said that the skewness is larger.

In step S1905, the CPU310cancels the change in contrast perceived by the frequency response characteristic of vision from the corrected perceived luminance contrast data, thereby performing conversion into luminance contrast data after skewness correction. In step S1902, the luminance contrast data is converted into frequency data and multiplied by the frequency response characteristic of vision at the observation distance, thereby simulating the perceived data. Therefore, in step S1905, the corrected perceived luminance contrast data is divided by the frequency response characteristic of vision at the observation distance on the frequency domain, thereby acquiring the corrected luminance contrast data.

The process advances to step S1906and the CPU310replaces the luminance contrast data of the texture data input in step S1901by the corrected luminance contrast data acquired in step S1905. Thus, the texture data after skewness correction is acquired. A method of converting YCbCr data into RGB data can perform conversion using equations (7) to (9) below.
R=Y+1.402·Cr(7)
G=Y−0.344·Cb−0.714·Cr(8)
B=Y+1.772·Cb(9)

By performing the correction processing for the texture data, as described above, correction can be performed so that the skewness of the perceived luminance contrast data at the observation distance of the decoration data becomes high.

Note that the method of correcting the texture data is not limited to the above-described one. For example, the texture data may be corrected by magnification processing. Alternatively, if an observation distance is assumed when designing the texture data, an assumed observation distance L0is held in the data server31or the storage unit302in association with the texture data. If, for example, the display observation distance when designing the texture data is 60 cm and the texture data is designed so that metal texture is high under this condition, the assumed observation distance L0is set to 60 cm. Then, in step S1802ofFIG.18, the assumed observation distance L0is acquired in addition to the texture data. Then, in step S1906, a magnification M is decided based on the ratio between the assumed observation distance L0and an observation distance L input to the observation distance input box507, by:
M=L/L0  (10)

The texture data is enlarged or reduced based on the thus calculated magnification M. By performing magnification processing of the texture data, as described above, the appearance of the texture data on the decoration data can be adjusted to the appearance when creating the texture data. That is, correction can be performed so that the skewness of the luminance histogram of the perceived luminance contrast data of the decoration data corresponding to the actual observation distance is almost equal to the skewness of the perceived luminance contrast data corresponding to the observation distance when creating the texture data. Note that the method of the texture data correction processing is not limited to the above-described one and any correction method can be used as long as the skewness of the luminance histogram of the perceived luminance contrast data perceived when the observer observes, at the observation distance, a print product on which the texture data is printed is high. As described above, the processing of the image processing apparatus30according to the third embodiment is executed.

As described above, according to the third embodiment, reference texture data acquired in advance is corrected so that the skewness of a luminance histogram becomes high in an image perceived when an observer observes, at an observation distance, a print product on which the texture data is printed, and is then used. This can generate texture data having a high luster feeling when performing observation at the observation distance. That is, it is possible to create decoration data having high metal texture. Furthermore, since the reference texture data need only be held, it is possible to perform processing by saving a memory, as compared with a case in which a plurality of texture data are held.

The above third embodiment has explained the example in which texture data is created by correcting acquired texture data so that the skewness of a luminance histogram becomes high in an image perceived when an observer observes, at an observation distance, a print product on which the texture data is printed. In the third embodiment as well, an illumination pattern may be held separately from the texture data, and composited with the corrected texture data, similar to the second embodiment. This can reproduce a high specular reflection characteristic as the characteristic of metal, thereby creating decoration data that reproduces more realistic metal texture.

Other Embodiments