Image processing device, image processing method, and program

Abstract

To solve the problem in which: since printing characteristics in printing decorated data is not considered before, when digital data is printed, the digital data is not always printed the same due to characteristics of printing equipment and printing medium such as a sheet used for printing.SOLUTION: An image processing apparatus sets an object area and acquires an output condition when outputting the object area. When acquiring a plurality of pieces of texture data for applying metallic expression on an image, the apparatus selects texture data based on the output condition, and applies the selected texture data to the object area.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to an image processing device, an image processing method, and a program. [Background technology]

[0002] A decoration technique is known that adds a metallic texture to an object in digital data by adding texture data to the object. Patent Document 1 describes a decoration technique that first acquires information about the light source at the location where the data decorated with the texture data is to be observed. Then, the texture data is corrected to faithfully reproduce the metallic reflection that occurs under the acquired light source, thereby generating data with a realistic texture. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-93287 Summary of the Invention [Problem to be solved by the invention]

[0004] However, conventional technologies did not take into consideration the printing characteristics when printing decorated data. When printing digital data, the digital data is not necessarily printed identically due to the characteristics of the printing device and the printing medium, such as the sheet used for printing. For example, an inkjet printer can produce a blurred print result compared to the digital data due to ink bleeding on the printing medium, but this blurring characteristic varies depending on the printing device and printing medium. Therefore, when printing using different printing devices, the printed texture results will differ depending on the printing device, resulting in the problem of the metal texture being perceived differently. In addition to the characteristics of the printing device, other factors that can cause this difference in printing characteristics include print resolution and type of printing medium.

[0005] An object of the present invention is to solve at least one of the problems of the prior art.

[0006] The object of the present invention is to provide a decoration technology that reproduces metallic appearance by adding texture data, Rendering Resolution The present invention aims to provide a technology for suppressing the deterioration of decorative effects due to the above-mentioned factors. [Means for solving the problem]

[0007] In order to achieve the above object, an image processing device according to one aspect of the present invention has the following configuration: Applying Metal Rendering to an Image A setting means for setting a target area; The aforementioned Metallic expression Reproduction a first acquiring means for acquiring a plurality of texture data for When outputting the target region The rendering resolution to use for A second acquisition means for acquiring the The aforementioned Rendering Resolution Based on At least one of the plurality of texture data a selection means for selecting texture data; The selected by the selection means Tate applying means for applying texture data to the target region; death, The plurality of texture data are data whose skewness of brightness histograms differs from each other when output at a predetermined rendering resolution. It is characterized by: [Effects of the Invention]

[0008] According to the present invention, in a decoration technique that reproduces a metallic appearance by adding texture data, when outputting a decorated image, Rendering Resolution By using the optimal texture data based on Rendering Resolution This can prevent the decorative effect from being reduced due to the coating.

[0009] Other features and advantages of the present invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which the same or similar elements are designated by the same reference numerals. [Brief explanation of the drawings]

[0010] The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. [Figure 1] 1A is a diagram showing the configuration of an image processing system to which an image processing apparatus according to a first embodiment of the present invention is applied, and FIG. 1B is a block diagram illustrating the hardware configuration of a control unit of the image processing apparatus according to the embodiment. [Figure 2] FIG. 2 is a functional block diagram illustrating functions of the image processing apparatus according to the first embodiment. [Figure 3] FIG. 4 is a diagram showing an example of a UI screen when creating decoration data in the UI of the image processing apparatus according to the first embodiment. [Figure 4] FIG. 1 is a diagram illustrating the skewness of a brightness histogram in an image. [Figure 5] 4 is a flowchart illustrating a procedure of processing performed by the image processing apparatus according to the first embodiment. [Figure 6] FIG. 10 is a diagram for explaining details of a method for acquiring texture data in S502. [Figure 7] 6 is a flowchart for explaining the process of selecting texture data in S505 of FIG. 5. [Figure 8] 8 is a flowchart for explaining the process of simulating print brightness contrast data in step S703 of FIG. 7 according to the first embodiment. [Figure 9] FIG. 1A shows an example of a lookup table linking rendering resolution and texture data, and FIG. 1B explains the texture pattern generation process. [Figure 10] 6 is a flowchart for explaining the texture pattern generation process in S506 of FIG. 5. [Figure 11] 7 is a flowchart illustrating the decoration data output process in S510 of FIG. 5. [Figure 12] A graph showing resolution characteristics with frequency on the horizontal axis and MTF on the vertical axis. [Figure 13] 5A to 5C are diagrams illustrating the effect of scaling texture data according to the first embodiment. [Figure 14]A graph showing the reflectance and wavelength dependence of gold, silver, and copper. [Figure 15] 10 is a flowchart illustrating a procedure of processing performed by an image processing apparatus according to a second embodiment. [Figure 16] 15 is a flowchart illustrating the process of selecting texture data to be used in generating print data to be used for the decorative portion based on print condition information in S1505 of FIG. 15 according to the second embodiment. [Figure 17] 17 is a flowchart illustrating the processing of S1603 in FIG. 16 according to the second embodiment of the present invention. [Figure 18] (A) is a diagram explaining color reproduction information, and (B) is a diagram showing the dynamic range of the output object, with luminance on the vertical axis. [Figure 19] FIG. 10 is a diagram showing the configuration of an image processing system to which an image processing device according to a modified example of the first embodiment of the present invention is applied. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the invention claimed. Although multiple features are described in the embodiments, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined arbitrarily. Furthermore, in the accompanying drawings, the same reference numerals are used to designate the same or similar components, and redundant explanations will be omitted.

[0012] [First embodiment] In the first embodiment, an example is described in which decoration data that reproduces the texture of metal (metallic expression) is created by adding texture data to a decoration area, and the decoration data is printed using an inkjet printer to observe a printed matter. An image processing device according to the embodiment first sets a decoration target area and acquires at least two or more texture data candidates to be added to the decoration target area. Next, information regarding the rendering resolution at which the decoration data is output, i.e., resolution characteristics, is acquired. Furthermore, based on the acquired information regarding the resolution characteristics, texture data with a high degree of distortion of the output image at the rendering resolution (described later, with improved glossiness) is selected from the acquired plurality of texture data and used for the decoration process. The acquired decoration data is then output to an output device (inkjet printer). The configuration and processing of the first embodiment are described below with reference to FIGS. 1 to 14.

[0013] FIG. 1A is a diagram showing the configuration of an image processing system to which an image processing device 101 according to a first embodiment of the present invention is applied.

[0014] An image processing device 101 according to the first embodiment is connected to a data server 102 and an output device 103. The data server 102 stores a plurality of texture data items used by a user for decoration processing that reproduces a metallic texture. The plurality of texture data items are input to the image processing device 101.

[0015] The image processing device 101 acquires data from a data server 102, issues control instructions to an output device 103, and transfers necessary information and data. The storage unit 105 stores an OS, a system program according to the embodiment, various application software, and parameter data required for various processes. This storage unit 105 can be configured using a hard disk or flash ROM. The control unit 104 includes a CPU (Central Processing Unit) 110 (FIG. 1B) and other components, and controls the processing of the image processing device 101 by loading and executing software stored in the storage unit 105 into a working memory 107. The hardware configuration of the control unit 104 is shown in FIG. 1B, and its functional configuration will be described later with reference to FIG. 2. The operation unit (hereinafter also referred to as "UI") 106, which serves as a user interface, processes inputs by a user and displays to the user for the execution of the above-mentioned processing, and includes input devices such as a keyboard and a pointing device, and a display device such as a monitor.

[0016] The output device 103 is, for example, an inkjet printer, and includes a data transfer unit, a printer control unit, a printing unit, etc. The output device 103 prints the decoration data acquired from the image processing device 101 by an inkjet recording method. In the embodiment described below, a case where the output device 103 is an inkjet printer will be described, but the output device 103 may also be an electrophotographic printer, or a display or projector.

[0017] FIG. 1B is a block diagram illustrating the hardware configuration of the control unit 104 of the image processing device 101 according to the embodiment.

[0018] The CPU 110 executes programs loaded in a RAM 112, which corresponds to the above-mentioned working memory 107, and controls the control processing by the control unit 104. A ROM 111 stores programs, various data, etc. The RAM 112 provides a work area for storing various data, etc. when the CPU 110 is operating, and is also used as an area for loading programs. An input / output interface (I / F) 113 controls the interface between the control unit 104 and the UI 106, a network, etc. An HDD (hard disk drive) 114 also functions as the storage unit 105 in FIG. 1(A) and stores programs and various data.

[0019] FIG. 2 is a functional block diagram illustrating the functions of the image processing device 101 according to the first embodiment.

[0020] The target area setting unit 201 acquires coordinate information of an object selected by the user as a target for decoration processing on a UI screen 300 (FIG. 3), which will be described later, and calculates the size of the object. The texture data acquisition unit 202 acquires at least two pieces of texture data associated with the decoration pattern selected by the user on the UI screen 300. The printing condition acquisition unit 203 acquires printing conditions set by the user on the UI screen 300. Note that, since printing is used as an example here, these printing conditions are used as printing conditions. However, if the output device 103 is a display, for example, these printing conditions may be used as output conditions. The texture data selection unit 204 selects one piece of texture data from the multiple pieces of texture data acquired by the texture data acquisition unit 202 based on the printing conditions acquired by the printing condition acquisition unit 203. The texture pattern generation unit 205 uses the texture data selected by the texture data selection unit 204 to generate a texture pattern corresponding to the object size set by the target area setting unit 201. The lighting data acquisition unit 206 acquires lighting data associated with the decoration pattern selected by the user on the UI screen 300. The illumination pattern generation unit 207 generates an illumination pattern according to the object size set by the target area setting unit 201, using the illumination data acquired by the illumination data acquisition unit 206. The decoration pattern generation unit 208 generates a decoration pattern by combining the texture pattern generated by the texture pattern generation unit 205 with the illumination pattern generated by the illumination pattern generation unit 207. The decoration pattern application unit 209 applies the decoration pattern generated by the decoration pattern generation unit 208 to an object selected by the user on the UI screen 300 as a target for decoration processing. The output control unit 210 performs processing to output, on the output device 103, an image including the object to which the decoration pattern has been applied by the decoration pattern application unit 209.

[0021] FIG. 3 is a diagram showing an example of a UI screen when creating decoration data on the UI 106 of the image processing apparatus 101 according to the first embodiment.

[0022] The UI screen in the first embodiment includes a texture pattern display area 305 that displays user-selectable texture patterns 306 and an edit data display area 301 that displays decoration data 302. The user specifies an application object 303 to which the user wants to apply gold or silver decoration from the decoration data 302. When a texture pattern 306 is selected from the texture pattern display area 305, the selected texture pattern is applied to the decoration target area 304 of the application object 303, resulting in metallic decoration. The UI 106 also includes a rendering resolution selection dropdown list 307 for acquiring the rendering resolution of the printed decoration data. Furthermore, the UI 106 also includes a printer model selection dropdown list 308, a print media selection dropdown list 309, a print quality selection dropdown list 310, and a print resolution selection dropdown list 311 for specifying print settings. Pressing a print button 312 initiates printing based on the specified print settings. Note that the UI illustrated in FIG. 3 is merely an example, and the UI according to this embodiment is not limited to this example.

[0023] Next, image statistics correlated with the level of metallic texture in this embodiment will be described with reference to FIG.

[0024] A characteristic of metallic materials is the strong metallic luster that is generated when the free electrons in the material and the electromagnetic waves of the illuminating light cause plasmon resonance. The perception of this metallic luster is one of the important factors in humans' perception of the texture of metal.

[0025] The perception of metallic texture based on glossiness is similar to the perception of texture of materials projected onto a two-dimensional image. The human brain can perceive the metallic texture of materials projected onto an image using statistical quantities in the image that are highly correlated with the aforementioned glossiness. Recent research has shown that the skewness of the brightness histogram contributes to the apparent glossiness of materials in an image. This skewness is a statistical quantity that represents the bias of the histogram in an image, and is calculated using the following equation (1) using the number of pixels in the image, n, the pixel values, xi (i = 1, 2, ..., n), the mean value of each pixel, x(-), and the standard deviation, s:

[0026] skewness={n / (n-1)(n-2)}×Σ{((xi-x(-)) / s} 3 ...Formula (1) Here, Σ indicates the sum of i=1 to n.

[0027] In the case of a symmetrical distribution, as shown in Figure 4(b), i.e., a normal distribution, the skewness is 0. In contrast, in the case of a distribution with a long left tail, as shown in Figure 4(a), the skewness is a negative value, and in the case of a distribution with a long right tail, as shown in Figure 4(c), the skewness is a positive value. Motoyoshi, Isamu, et al., "Image statistics and the perception of surface qualities," Nature 447.7141 (2007): 206-209, states that the more positive the skewness of the brightness histogram in an image (Figure 4(c)), the higher the perceived apparent glossiness.

[0028] As mentioned above, the glossiness of a material is a very important factor in perceiving a metallic texture. In other words, using texture data in which the skewness of the brightness histogram in an image is large in positive value leads to an improvement in the apparent glossiness, i.e., an improvement in the perceived metallic texture. In this embodiment, a pattern having such image characteristics is called a "texture pattern," and data obtained by imaging the texture pattern is called "texture data."

[0029] In addition, reproducing colors that depend on the plasma frequency of metals is also an important factor in perceiving metallic textures.

[0030] FIG. 14 is a diagram showing the reflectance and wavelength dependency of gold, silver, and copper.

[0031] Each metal has a unique vibration frequency that determines how much light energy it can reflect. For example, gold is unable to fully reflect the high-energy short-wavelength components, so it appears yellowish, while silver is able to reflect short-wavelength components as well, so it appears white. In other words, each type of metal has its own unique color. For this reason, reproducing the color of a metal also improves the perceived metallic texture.

[0032] 5 is a flowchart illustrating the procedure of processing performed by the image processing device 101 according to the first embodiment. In the embodiment, an example is shown in which the image processing device 101 is located outside the output device 103, but it may of course be located inside the output device 103. The processing shown in this flowchart is achieved by the CPU 110 executing a program loaded in the RAM 112.

[0033] First, in S501, the CPU 110 functions as the target area setting unit 201, sets a decoration target area to which texture data is to be applied, and outputs the target area to the texture pattern generation unit 205. One example of a method for setting this decoration target area is to set an object designated by the user on the UI 106 as the application object, and, for example, set text in the application object 303 as the decoration target area 304, as shown in FIG. 3 . Here, the application object and decoration target area do not have to be text objects. For example, they may be graphic objects such as circles or diamonds, or clip art such as medals or trophies. Alternatively, instead of designating an object, the user may designate two points—the start point and the end point of a rectangle that are diagonally opposite each other—on the decoration data, and the rectangular area encompassing these two points may be set as the decoration target area. Furthermore, for example, the entire background of the decoration data may be set as the decoration target area.

[0034] Although FIG. 3 shows an example in which only one application object, the application object 303, is designated as the application object, multiple objects may be designated. Of course, the decoration target area may be set automatically rather than by the user. For example, when an automatic gold and silver decoration button (not shown) is pressed, the text area with the largest font size in the decoration data may be automatically set as the decoration target area. Alternatively, a highly eye-catching area in the decoration data detected by a known saliency detection technique may be set as the decoration target area. This allows the user to create gold and silver decoration data without having to go through the trouble of selecting a decoration area. Furthermore, even users with little design experience can effectively perform gold and silver decoration processing.

[0035] Next, the process proceeds to S502, where the CPU 110 functions as the texture data acquisition unit 202 to acquire texture data. This texture data is transmitted from the data server 102 to the image processing device 101 and input to the texture data acquisition unit 202. This acquired texture data corresponds to a pattern selected by the user as a pattern suitable for the decorative area from the patterns displayed in the texture pattern list 305. Details of the texture data and texture patterns input to the texture data acquisition unit 202 will be described later.

[0036] Next, the process proceeds to S503, where the CPU 110 functions as the illumination data acquisition unit 206 to acquire illumination data. This illumination data is transmitted from the data server 102 to the image processing device 101, input to the illumination data acquisition unit 206, and output to the illumination pattern generation unit 207. The illumination data acquisition unit 206 acquires illumination data associated with the decoration pattern selected by the user on the UI screen. Details of the illumination pattern and illumination data will be described later.

[0037] Next, the process proceeds to S504, where the CPU 110 functions as the printing condition acquisition unit 203 and acquires the printing conditions. In the first embodiment, the printing condition acquired by the printing condition acquisition unit 203 is the "rendering resolution." The rendering resolution acquired by the printing condition acquisition unit 203 is output to the texture data selection unit 204. The rendering resolution can be acquired as the rendering resolution input by the user via the rendering resolution selection dropdown list 307 in FIG. 3. Alternatively, instead of acquiring the rendering resolution input by the user, a correspondence between the print quality and the rendering resolution may be stored in advance in the storage unit 105, and the rendering resolution corresponding to the print quality specified via the print quality selection dropdown list button 310 may be acquired. Alternatively, a correspondence between the performance of the control unit 104 or the working memory 107 of the image processing device 101 and the rendering resolution may be stored in advance in the storage unit 105, and the rendering resolution corresponding to the image processing device that executes the metallic decoration processing may be acquired. Also, for example, the upper limit of the image size that can be processed by the metallic decoration process may be stored in advance in the storage unit 105, and a rendering resolution when the poster size exceeds the upper limit and a rendering resolution when the upper limit is not exceeded may be set. In short, anything is acceptable as long as the rendering resolution for the decoration data can be obtained.

[0038] Next, the process proceeds to S505, where the CPU 110 functions as the texture data selection unit 204 and selects texture data to be used for generating decoration data from the texture data acquired in S502, based on the rendering resolution acquired in S504. The details of this selection method are described below.

[0039] The texture data selection unit 204 simulates print brightness contrast data for the multiple texture data acquired by the texture data acquisition unit 202 based on the rendering resolution acquired by the printing condition acquisition unit 203. For the simulated print brightness contrast data, the texture data selection unit 204 calculates the skewness of the brightness histogram based on the above formula (1) and selects texture data with a high degree of skewness. The texture data selected in this way is output to the texture pattern generation unit 205.

[0040] Next, we will explain the print luminance contrast data calculated by the texture data selection unit 204. The print luminance contrast data is data that simulates the luminance contrast output by the output device 103, taking into account the resolution characteristics of the output device 103.

[0041] First, the texture data is converted into brightness contrast data. If the input texture data is RGB data, it can be converted into YCbCr using equations (2) to (4). The conversion equation from RGB to YCbCr is an example, and other conversion equations may also be used.

[0042] Y=0.299·R+0.587·G+0.114·B …Formula (2) Cb=-0.169·R-0.331·G+0.5·B…Formula (3) Cr=0.5·R-0.419·G-0.081·B…Formula (4) Next, a method for simulating print luminance contrast data by applying resolution characteristics to the luminance contrast data will be described.

[0043] First, the luminance contrast data is converted into frequency data. This conversion to frequency data can be performed using known techniques such as two-dimensional Fourier transform (FFT: Fast Fourier Transform). The frequency contained in the luminance contrast data can be calculated based on the number of pixels in the texture data and the size after printing. For example, the highest frequency f [cycle / mm] contained in the texture data when the size of the texture data after printing is s [mm] can be calculated using the following equation (5), where n [pix] is the number of pixels in the texture data.

[0044] f=n / 2s…Equation (5) As described above, each frequency in the texture data calculated based on the number of pixels in the texture data and the size after printing is multiplied by the resolution characteristics described below. The obtained frequency data is then inversely converted into brightness contrast data, thereby obtaining print brightness contrast data that simulates the contrast characteristics when the output device 103 actually outputs.

[0045] Next, the resolution characteristics of the printing device will be described.

[0046] In a printing device, the resolution characteristics of rendering data differ from the resolution reproduction characteristics when printing on a print medium (hereinafter referred to as print resolution characteristics), and the print resolution characteristics differ depending on the frequency characteristics of the rendering data. These characteristics are shown in Figure 12.

[0047] FIG. 12 is a graph showing print resolution characteristics, with the horizontal axis representing frequency and the vertical axis representing MTF.

[0048] MTF indicates how faithfully the contrast of input data can be reproduced on a printed image, and it is known that it can be calculated using the Fourier transform method or the contrast method. The closer the MTF is to 1, the more faithfully the contrast of the input data can be reproduced, and the closer it is to 0, the blurrier the print will be.

[0049] In Figure 12, solid line 1201 and dashed line 1202 illustrate the resolution characteristics when printing at different rendering resolutions r1 and r2 (r1 > r2). When comparing the contrast printed at the two rendering resolutions, solid line 1201 > dashed line 1202, so the contrast when output at rendering resolution r1 is stronger than the contrast when output at rendering resolution r2. In other words, when data that has been decorated at a rendering resolution different from that used to create the texture data is output, the degree of contrast reproduction changes even if the data has been decorated in the same way.

[0050] If the decoration data is output under conditions with lower print resolution characteristics than when the texture data was created, the contrast will be weaker, causing the distribution of the texture data's brightness histogram to narrow toward the center of the peak and reducing skewness. As a result, the intended metallic texture of the texture data may not be fully reproduced, and the decoration effect may be reduced.

[0051] Printing resolution characteristics also vary depending on the printing method. For example, it is generally known that the resolution characteristics of inkjet printers and electrophotographic printers differ. That is, inkjet printers are known to have higher resolution than electrophotographic printers. This is due to the different methods of gradation expression. Inkjet printers use a dot-dispersed method of gradation expression, which expresses gradation through the number and pattern of tiny dots. In contrast, electrophotographic printers use a dot-concentrated method of gradation expression, which creates halftone dots by grouping multiple dots together and expresses gradation through their size. Therefore, when texture data created for printing with an inkjet printer is printed with an electrophotographic printer, the perceived resolution changes even if the same decorative data is applied. As a result, the appearance of the texture data may differ from what was expected, and the metal texture may not be fully reproduced, resulting in a reduced decorative effect.

[0052] In addition, although the embodiment assumes that the texture data is rectangular as an example, the texture data is not necessarily rectangular. In such cases, the frequency in the texture data may be calculated based on the width in accordance with the shape of the texture data, or the frequency in the texture data may be calculated based on the height. The frequency in the texture data may also be calculated based on the average value of the height and width.

[0053] Next, the process proceeds to S506, where the CPU 110 functions as the texture pattern generation unit 205, and cuts out the texture pattern selected in S505 so that it has a shape that fits the target region specified in S501. Next, the process proceeds to S507, where the CPU 110 functions as the illumination pattern generation unit 207, and generates an illumination pattern by scaling the illumination data acquired in S503 to match the size of the application object. Then, the process proceeds to S508, where the CPU 110 functions as the decoration pattern generation unit 208, and generates a decoration pattern by combining the texture pattern generated in S506 and the illumination pattern generated in S507.

[0054] The process then proceeds to S509, where the CPU 110 functions as the decoration pattern application unit 209 and combines the decoration pattern generated in S508 with the decoration application area. This combination method may involve, for example, superimposing or replacing the decoration pattern on the decoration target area 304 in Fig. 3. The process then proceeds to S510, where the CPU 110 functions as the output control unit 210 and performs output control processing for outputting the decoration data generated in S509 on the output device 103.

[0055] Next, each step in the flowchart of FIG. 5 will be described in detail.

[0056] First, FIG. 6 is a diagram for explaining the details of obtaining texture data in S502.

[0057] 6, 601, 602, and 603 correspond to the texture patterns displayed in the texture pattern list 305 in Fig. 3. Texture data 604, 605, and 606 correspond to the texture patterns 601, 602, and 603, respectively, and are composed of multiple pieces of texture data that differ from one another according to resolution characteristics. The texture data 604, 605, and 606 are stored in the data server 102.

[0058] Now, when the user selects a texture pattern, for example, from the texture pattern list 305 in Fig. 3, multiple pieces of texture data associated with the selected texture pattern are acquired from the server 102. In the embodiment, an example has been shown in which multiple pieces of texture data are acquired directly from the data server 102, but it is of course also possible to acquire texture data that has been acquired in advance in the storage unit 105.

[0059] FIG. 7 is a flowchart illustrating the process of selecting texture data in S505 of FIG.

[0060] First, in S701, the CPU 110 acquires the resolution characteristics for the printing conditions (here, the rendering resolution) acquired in S504. Next, the process proceeds to S702, where the CPU 110 calculates luminance contrast data for the texture data acquired in S502 using equations (2) to (4). Next, the process proceeds to S703, where the CPU 110 simulates print luminance contrast data for the luminance contrast data calculated in S702 based on the resolution characteristics acquired in S701. Next, the process proceeds to S704, where the CPU 110 calculates the skewness for the print luminance contrast data calculated in S703 using equation (1). Next, the process proceeds to S705, where the CPU 110 determines whether the above processing has been applied to all texture data acquired in S502. If these processing steps have been completed for all texture data, the process proceeds to S706. If not, the process proceeds to S702, where the processing steps from S702 to S704 are repeated. In S706, the CPU 110 selects texture data to be used for the gold and silver decoration process based on the degree of distortion calculated in S704. Here, the texture data with the highest calculated degree of distortion is selected.

[0061] As another selection method, reference texture data may be determined in advance from the list of texture data shown in Figure 6 as a reference, and texture data showing a higher distortion than the distortion calculated from that reference texture data may be selected. Furthermore, when multiple texture data are candidates, texture data with an average luminance closest to the reference texture data may be selected, or texture data with a hue or saturation closest to the reference texture data may be selected. Of the multiple candidates, any texture data other than the texture data with the furthest color from the reference texture data may be selected. In short, any texture data showing a higher distortion than the distortion calculated from the reference texture data may be selected.

[0062] In this way, by selecting texture data with a high degree of distortion on output data that simulates the actual printing state, it is possible to select texture data with a high metallic feel at the expected resolution characteristics.

[0063] In the above description with reference to FIG. 7, an example was described in which steps S701 to S706 are executed to select texture data after the rendering resolution is acquired in S504. However, the embodiment is not limited to this. For example, the processes of steps S701 to S705 may be applied in advance to each piece of retained texture data in accordance with the expected resolution characteristics. That is, a correspondence table (e.g., FIG. 9A) in which appropriate texture data is registered in association with rendering resolutions is stored in advance in the storage unit 105, and appropriate texture data is selected by referring to the correspondence table in accordance with the rendering resolution acquired in S504. This allows some of the processes related to texture data selection to be omitted, thereby shortening the processing time.

[0064] Another method for selecting texture data is to create texture data in advance that will have a high degree of distortion at a certain rendering resolution, and determine the correspondence between the texture data and the high degree of distortion at the rendering resolution.

[0065] FIG. 8 is a flowchart for explaining the process of emulating print brightness contrast data in S703 of FIG.

[0066] In S801, the CPU 110 acquires the resolution characteristics corresponding to the rendering resolution acquired in S701. Next, the process proceeds to S802, where the CPU 110 applies the resolution characteristics acquired in S801 to the reference texture data. Next, the process proceeds to S803, where the CPU 110 calculates the difference between the texture data before and after the resolution characteristics have been applied. Then, the process proceeds to S804, where the CPU 110 adds the difference calculated in S803 to the reference texture data.

[0067] This method allows for the creation of texture data with a higher resolution than the reference texture data at the rendering resolution used when the texture data was created. This allows for the creation and storage of texture data with a higher degree of distortion. Similarly, texture data with a higher degree of distortion can be created by measuring the resolution characteristics at an appropriate rendering resolution and emphasizing the frequency components that deteriorate due to the resolution characteristics compared to the reference texture data.

[0068] Another method is to scale texture data created for a standard rendering resolution by the ratio between the desired rendering resolution and the standard rendering resolution. For example, if you want to create texture data for 300 dpi using texture data created for 600 dpi as a reference, you can simply reduce the width and height of the texture data created for 600 dpi by half, since the rendering resolution ratio is 0.5.

[0069] FIG. 13 is a diagram illustrating the effect of scaling texture data according to the first embodiment.

[0070] In Figure 13, texture data 1300 created so that distortion is high at a rendering resolution of 600 dpi is considered as the reference. This texture data can be applied as is at the same magnification when the rendering resolution is 600 dpi without any problems. On the other hand, if this texture data 1300 is applied as is when the rendering resolution is 300 dpi, only a portion 1301 of the texture data will be decorated. As a result, the originally expected brightness distribution with high distortion changes and the distortion decreases, making it impossible to fully reproduce the metallic texture and reducing the decorative effect.

[0071] In contrast, as shown in 1302, if this texture data is scaled by 0.5 before application, decoration can be performed taking into account the entire texture data. As a result, the originally expected highly skewed brightness distribution can be roughly maintained, and the metallic texture can be reproduced satisfactorily. In other words, with this method, even if the rendering resolution is different from when the texture data was created, the brightness distribution shape of the texture data can be maintained, making it possible to create texture data with a higher degree of skewness.

[0072] As a correspondence relationship between rendering resolution and texture data with high distortion, for example, a threshold value may be set for the rendering resolution, and the texture data to be selected may be switched depending on whether the rendering resolution is equal to or greater than the threshold value or less than the threshold value. Also, as shown in Figure 9(A), a lookup table linking the rendering resolution with the texture data to be selected may be stored.

[0073] FIG. 9A is a diagram showing an example of a lookup table that associates rendering resolution with texture data.

[0074] Fig. 9(B) is a diagram illustrating the texture pattern generation process, and Fig. 10 is a flowchart illustrating the texture pattern generation process of S506 in Fig. 5. The texture pattern generation process performed in S506 will be described below with reference to Fig. 9(B) and Fig. 10.

[0075] First, in S1001, the CPU 110 determines whether the size of the texture data selected in S505 is less than the size of the target area of ​​the application object. If it is determined that the size of the texture data is less than the size of the target area of ​​the application object, the process proceeds to S1002; otherwise, the process proceeds to S1003. In this embodiment, the comparison of sizes refers to a comparison of the long and short sides of the texture data with the long and short sides of the target area of ​​the application object. If either the long or short side of the texture data is longer than the size of the target area of ​​the application object, the process proceeds to S1003.

[0076] In S1002, the CPU 110 tiles the texture data 900 as shown in Fig. 9(B). This tiling process is performed until the sizes of the short and long sides of the tiled texture data are equal to or larger than the sizes of the short and long sides of the application object 303 in Fig. 3, for example. When performing this tiling, the texture data may be tiled so that they do not overlap, or may be tiled with some overlap allowed.

[0077] The process then proceeds to S1103, where the CPU 110 aligns the texture data acquired in either S1101 or S1102 with the target area of ​​the application object, and then clips the texture data to fit the shape of the decoration target area to generate a texture pattern. This alignment to the application object can be achieved, for example, by aligning the texture data and the target area of ​​the application object based on the upper left corner of the object. Of course, alignment can also be achieved without using the upper left corner as a reference. Essentially, any method is acceptable as long as the texture data is aligned so that it covers the entire decoration target area. The aligned texture data is then clipped to fit the shape of the decoration target area. This clipping method can be achieved, for example, by generating a mask image of the decoration target area using RGB values ​​as a threshold and applying the mask image to the texture data. Furthermore, if the application object is SVG-formatted data, the SVG clippath function can also be used. Essentially, any method is acceptable as long as it allows the texture data to be clipped to fit the shape of the decoration target area.

[0078] FIG. 11 is a flowchart illustrating the decoration data output process in S510 of FIG.

[0079] In S1101, the CPU 110 inputs the RGB image of the document that was subjected to the decoration process in S509. Next, the process proceeds to S1102, where the CPU 110 performs color correction, converting the RGB colors of the document into RGB values ​​suitable for printing, for example. This color correction process may be performed using any known suitable process. Next, the process proceeds to S1103, where the CPU 110 performs color separation, converting the RGB values ​​into the amount of ink used for each ink. This color separation process may be performed using any known suitable process. The inks assumed here may be color separation into CMYK inks, or may be color separation into inks containing special color inks such as metallic inks. Next, the process proceeds to S1104, where the CPU 110 performs quantization, converting the amount of ink used for each color by the print head into the presence or absence of dots that will actually be printed. This quantization process may be performed using any known method, such as error diffusion or dithering. Once the quantized dot data is sent to the print head and preparation of one scan's worth of dot data is complete, actual printing is performed on the print paper using the print head. Then, in S1105, the CPU 110 determines whether processing has been completed for all pixels of the document. If it is determined that processing has been completed, this processing ends. On the other hand, if it is determined that processing has not been completed, the process returns to S1101 and the rest of the document is processed. Thereafter, S1101 to S1105 are repeated until processing of the document image data is completed.

[0080] In the first embodiment, texture data is selected according to the rendering resolution, but other printing conditions that affect the print resolution characteristics may also be used instead of the rendering resolution. For example, similar processing is possible for the printing method, printing model, media type, and print quality.

[0081] For example, it is possible to determine the printing method (inkjet printer or electrophotographic printer) from the printing model specified by the user in the UI 106, and switch the texture data to be selected depending on the printing method. Similar processing is also possible for combinations of multiple printing conditions, such as rendering resolution and printing method.

[0082] Next, the effects of the first embodiment of the present invention will be described.

[0083] As shown in Figure 12, when decoration data is printed at different rendering resolutions, the degree of contrast reproduction changes, even for data with the same decoration applied. If decoration data is output under conditions with lower resolution characteristics than when the texture data was created, the contrast will be weaker, causing the brightness distribution of the texture data to narrow toward the center of the peak and reducing skewness. As a result, the intended metallic texture of the texture data may not be reproduced sufficiently, reducing the decorative effect.

[0084] These resolution characteristics also vary depending on the printing method. For example, it is generally known that inkjet printers have higher resolution than electrophotographic printers. This is due to the different methods of gradation expression. Inkjet printers use a dot-dispersed method of gradation expression, which expresses gradation through the number and pattern of tiny dots. In contrast, electrophotographic printers use a dot-concentrated method of gradation expression, which creates halftone dots by gathering multiple dots together and expresses gradation through their size. Therefore, inkjet printers, which can express images with smaller dots, can express images at a higher resolution than electrophotographic printers.

[0085] Therefore, when texture data created with the assumption that it will be output by an inkjet printer is output by an electrophotographic printer, the resolution changes even if the data has the same decoration applied. As a result, the appearance of the texture data may differ from what was expected, and the metallic texture may not be fully reproduced, resulting in a reduced decorative effect.

[0086] According to the first embodiment, by switching between textures that are output with a high degree of distortion depending on the expected resolution characteristics, it is possible to suppress a decrease in the metallic decorative effect.

[0087] In the first embodiment, appropriate texture data was selected from the multiple acquired texture data according to the rendering resolution, which is information about the resolution characteristics, and used for the decoration process. However, it is also possible to acquire one reference texture data, correct that reference texture data according to the rendering resolution of the decoration data, and use it for the decoration process. Information about the resolution characteristics when observing data that has been metallically decorated using texture data may be acquired, and the previously acquired reference texture data may be corrected so that the distortion in the image output at the resolution characteristics is increased. This allows for processing that requires less memory than storing multiple texture data.

[0088] In the above embodiment, an example was described in which decoration data to be output to an inkjet printer was created. However, when the created decoration data is displayed on a display, i.e., when a preview is displayed, the texture data may be switched according to the rendering resolution set in the rendering resolution input text box 307. Furthermore, a different resolution may be set for the preview display displayed on the display, separate from the decoration data to be printed, which is set in the rendering resolution input text box 307, and the texture data for the preview display may be switched according to the display resolution of the preview display. This allows the user to create decoration data while checking in advance on the display the metallic texture that will be reproduced in the texture data after printing.

[0089] In the first embodiment, the functions of the functional block diagram shown in Fig. 2 are implemented by the image processing device 101. However, some of these functions may be implemented by a device other than the image processing device, for example, a processing server 1900 as shown in Fig. 19.

[0090] The processing server 1900 may be, for example, an on-premise physical server or a virtual server configured on a cloud service. Of course, the data server 102 may be included in the processing server 1900. When the volume of decoration data is very large (for example, decoration data of size A0), processing can be sped up by configuring some of the functional blocks with a high processing load to be configured on a processing server with higher processing power than the image processing device. Furthermore, since only functional blocks with a low processing load can be performed on the image processing device 101, the processing power of the image processing device 101 may be lower than that of the processing server 1900. In other words, operation using an image processing device such as a smartphone or tablet terminal becomes possible, making it easy to create decoration data by remote operation.

[0091] [Second embodiment] In the first embodiment, an example was described in which a rendering resolution is acquired from a plurality of acquired texture data as information related to the printing conditions, and appropriate texture data is selected according to the rendering resolution and used in the decoration processing. In contrast, in the second embodiment, appropriate texture data is selected from a plurality of acquired texture data based on information related to the color gamut, which is a printing condition, and used in the decoration processing. The obtained decoration data is then output to the printing device. The configuration and processing of the second embodiment will be described below with reference to Figures 15 to 18. In the second embodiment, the configuration of the image processing system and functional blocks is the same as that in the first embodiment, so a description thereof will be omitted.

[0092] Fig. 15 is a flowchart illustrating the procedure of processing performed by the image processing device 101 according to the second embodiment. This flowchart corresponds to Fig. 5 of the first embodiment described above, and since steps S1501 to S1503 in Fig. 15 are similar to steps S501 to S503 in Fig. 5, their description will be omitted. However, while in S502 the texture data 604, 605, and 606 were composed of multiple pieces of texture data according to the resolution characteristics, in S1502 they are composed of multiple pieces of texture data according to the color reproduction characteristics.

[0093] In S1504, printing conditions relating to color reproduction characteristics different from those in S504 are acquired. The printing conditions acquired by CPU 110 in S1504 are conditions relating to the color gamut. Generally, the color gamut is determined by the type of printer, the print medium (also called media), print quality, etc. Each of these can be set on UI screen 300 in FIG. 3, where in FIG. 3, the printer type (model) is set in print model selection dropdown list 308, the type of print medium in print media selection dropdown list 309, and the print quality in print quality selection dropdown list button 310. Although an example is shown in which all of these printing condition settings can be set on the UI screen, some of the settings can be omitted in the case of a printer that does not have these settings.

[0094] Next, the process proceeds to S1505, where the CPU 110 selects texture data to be used in generating print data to be used for the decoration portion from the texture data acquired in S1502 based on the information on printing conditions related to color reproduction characteristics acquired in S1504. In this way, texture data is selected based on the information on printing conditions. In S1506 to S1510, processes similar to S506 to S510 in FIG. 5 of the first embodiment are performed, and the decoration data is output (printed).

[0095] Fig. 16 is a flowchart illustrating the process of selecting texture data to be used in generating print data to be used for the decorative portion based on the information on the printing conditions in S1505 in Fig. 15. This flowchart corresponds to Fig. 7 in the first embodiment.

[0096] First, in S1601, the CPU 110 generates color reproduction information based on the printing condition information acquired in S1504. This color reproduction information can be generated by measuring the color gamut for each printing condition in advance, creating a database, and then selecting from the database based on the specified printing conditions. Various methods for measuring the color gamut have been proposed, but the second embodiment is not dependent on any particular measurement method and any measurement method may be used.

[0097] Next, the process proceeds to S1602, where the CPU 110 calculates luminance contrast data for the acquired texture data using equations (2) to (4). Next, the process proceeds to S1603, where the CPU 110 simulates the print luminance contrast data. In S703 of FIG. 7, the print luminance contrast data was simulated based on the rendering resolution, but in the second embodiment, the print luminance contrast data is simulated based on the information about the color gamut acquired in S1601. Next, the process proceeds to S1604, where the CPU 110 calculates the skewness of the print luminance contrast data using equation (1). Then, in S1605, the CPU 110 determines whether processing has been applied to all texture data, and repeats the processes of S1602 to S1604 until processing of all pixels is completed. In S1606, the same process as S706 of FIG. 7 is performed.

[0098] The method for simulating S1603 here is, for example, performed using a flowchart such as that shown in FIG. 17, but this process may be performed in advance for each printing condition to generate the results, or this flow may be performed when S1603 is executed.

[0099] FIG. 17 is a flowchart illustrating the process of applying color reproduction characteristics to texture data in S1603 of FIG. 16 according to the second embodiment of the present invention.

[0100] In S1701, the CPU 110 acquires the color reproduction information generated in S1601. Next, the process proceeds to S1702, where the CPU 110 applies the color reproduction information acquired in S1701 to the reference texture data. Next, the process proceeds to S1703, where the CPU 110 calculates the difference between the texture data before and after the color reproduction information has been applied. Then, the process proceeds to S1704, where the CPU 110 adds the difference calculated in S1703 to the reference texture data, and this process ends.

[0101] Figure 18(A) is a diagram explaining color reproduction information. This diagram shows the color gamut of an output object at a certain hue angle, with saturation on the horizontal axis and lightness on the vertical axis. It is known that this color gamut changes depending on printing conditions such as the printing method, printing model, and media.

[0102] 18(A), solid line 1800 and dashed line 1801 indicate the color gamut that can be output by different printing models d1 and d2, respectively. Comparing the color gamuts output by the two printing models, in the target region having a high-brightness region 1803, solid line 1800 > dashed line 1801, so the color gamut when output by printing model d1 is wider than the color gamut when output by printing model d2. On the other hand, in the target region having a low-brightness region 1804, solid line 1800 < dashed line 1801, so the color gamut when output by printing model d2 is wider than the color gamut when viewed on printing model d1.

[0103] Next, the effects of the second embodiment of the present invention will be described.

[0104] As shown in Figure 18(A), when decorative data is output using a printer model that is different from the one used to create the texture data, even if the same decorative data is used, the brightness bands that output a wide color gamut and the brightness bands that output a narrow color gamut will vary depending on the printer model. As a result, the appearance of the texture data may differ from what was expected, and the metallic texture may not be fully reproduced, reducing the decorative effect.

[0105] Therefore, according to the second embodiment, by switching and using texture data depending on the color gamut in which a texture with a high degree of distortion is expected to be output, it is possible to suppress a decrease in the metallic decorative effect.

[0106] (Variation) In the above-described embodiment, the color reproduction characteristics are described as lightness-saturation characteristics as shown in Fig. 18(A). However, among the color reproduction information, it is also possible to specialize in the reproduction characteristics of luminance (luminance dynamic range). Since the metallic decorative effect is highly dependent on the distortion characteristics of luminance, the printing characteristics of the luminance dynamic range may be used in place of the second embodiment.

[0107] This example will be explained with reference to FIG.

[0108] 18B is a diagram showing the dynamic range of an output, with the vertical axis representing brightness. It is known that this dynamic range changes depending on printing conditions such as media and printer model.

[0109] In Figure 18(B), solid line 1810 and dashed line 1811 indicate the dynamic ranges that can be output by different media m1 and m2, respectively. Comparing the dynamic ranges that can be output by the two media, the target region having high-brightness region 1812 can only be output by medium m1. On the other hand, the target region having low-brightness region 1813 can only be output by medium m2.

[0110] In other words, if decorated data is output on a medium different from the one used to create the texture data, the luminance ranges that can and cannot be output will change depending on the medium, even if the data has been decorated in the same way. As a result, the texture data may look different from what was expected, and the metallic texture may not be fully reproduced, reducing the decorative effect.

[0111] Therefore, according to this modification, by switching and using texture data that is output with a high degree of distortion depending on the expected dynamic range, it is possible to suppress a decrease in the metallic decorative effect.

[0112] (Other embodiments) The present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0113] The present invention is not limited to the above-described embodiments, and various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the following claims are appended to apprise the public of the scope of the present invention. [Explanation of symbols]

[0114] 101...image processing device, 102...data server, 103...output device, 104...control unit, 105...storage unit, 110...CPU, 112...RAM, 201...target area setting unit, 203...printing condition acquisition unit, 204...texture data selection unit, 208...decorative pattern generation unit

Claims

1. A setting means for setting a target area on an image to which a metal representation is to be applied; a first acquiring means for acquiring a plurality of texture data for reproducing the metal appearance; a second acquisition means for acquiring a rendering resolution to be used when outputting the target region; a selection means for selecting at least one texture data from the plurality of texture data based on the rendering resolution; applying means for applying the texture data selected by the selecting means to the target region; The image processing device is characterized in that the plurality of texture data are data in which the skewness of brightness histograms differs from one another when output at a predetermined rendering resolution.

2. 2. The image processing apparatus according to claim 1, wherein said selection means selects texture data from said plurality of texture data based on the skewness of a brightness histogram when said plurality of texture data are output.

3. The image processing device described in Claim 2, characterized in that the selection means selects texture data from the plurality of texture data based on the skewness of the brightness histogram when the plurality of texture data are output with resolution characteristics corresponding to the acquired rendering resolution.

4. 4. The image processing apparatus according to claim 1, wherein the selection means selects texture data in which the skewness of the brightness histogram when output at the predetermined rendering resolution indicates a positive value.

5. 5. The image processing apparatus according to claim 1, wherein the selection means determines reference texture data from the plurality of texture data, and selects texture data having a skewness of a luminance histogram greater than that of the reference texture data.

6. 6. The image processing apparatus according to claim 5, wherein, when there is a plurality of texture data whose skewness of the brightness histogram is greater than that of the reference texture data, the selection means selects texture data whose color is close to that of the reference texture data.

7. 7. The image processing device according to claim 6, wherein the color includes at least one of hue, saturation, and average luminance.

8. further comprising a storage means for storing texture data corresponding to the rendering resolution; 8. The image processing apparatus according to claim 1, wherein the selection means selects the texture data by referring to the storage means in accordance with the rendering resolution acquired by the second acquisition means.

9. 9. The image processing device according to claim 1, wherein the first acquisition means acquires a plurality of texture data corresponding to a texture pattern selected via a screen and corresponding to the rendering resolution.

10. further comprising an illumination data acquisition means for acquiring illumination data; 10. The image processing apparatus according to claim 1, wherein the applying means further combines the texture data selected by the selecting means with an illumination pattern based on the illumination data and applies the combined data to the target area.

11. 11. The image processing device according to claim 1, wherein, when a size of the target area is larger than a size of the texture data, the applying means applies the texture data to the target area by tiling the texture data.

12. An image processing device described in any one of claims 1 to 11, characterized in that it further has an output means for outputting the image to which the selected texture data has been applied to the target area as data for printing.

13. A setting step of setting a target area on an image to which a metal representation is to be applied; a first acquisition step of acquiring a plurality of texture data for reproducing the metal appearance; a second acquisition step of acquiring a rendering resolution to be used when outputting the target region; a selection step of selecting at least one texture data from the plurality of texture data based on the rendering resolution; an applying step of applying the texture data selected in the selecting step to the target region, An image processing method, wherein the plurality of texture data are data that have different degrees of skewness in brightness histograms when output at a predetermined rendering resolution.

14. A program for causing a computer to execute all of the respective means of the image processing device according to any one of claims 1 to 12.

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