Patent Publication Number: US-2019196210-A1

Title: Lenticular display, method for forming lenticular image, method for manufacturing lenticular display, and program for forming lenticular image

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of International Application No. PCT/JP2017/032369, filed Sep. 7, 2017, the disclosure of which is incorporated herein by reference in its entirety. Further, this application claims priority from Japanese Patent Application No. 2016-190166, filed Sep. 28, 2016, the disclosure of which is incorporated herein by reference in its entirety. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a lenticular display, a method for forming a lenticular image, a method for manufacturing a lenticular display, and a program for forming a lenticular image. 
     2. Related Art 
     A lenticular display has been known as a medium that displays different images depending on a viewing angle. In the lenticular display, a lenticular lens is used in which convex lenses are arranged side by side, and the convex lenses each have a convex surface. 
     Typically, in the lenticular display, image strips (lenticular image) obtained by combining a plurality of images that are interlaced are arranged on a back-face side (facing away from the surface of the convex lenses) of the lenticular lens. When these image strips are observed through the lenticular lens, one type or two or more types of images among the image strips are displayed depending on an observing angle. 
     Now, as an example, a case where a display image A (hereinafter also referred to as “image A”) and a display image B (hereinafter also referred to as “image B”), the display image A and the display image B including different characters, are displayed separately in one lenticular display will be described with reference to  FIGS. 6 to 8 . 
     As illustrated in  FIG. 8 , a lenticular display  100  has a lenticular lens  104  in which a plurality of convex lenses  102  each having a convex surface are arranged side by side. On a back-face side of the lenticular lens  104  (bottom side in  FIG. 8 ), display image strips An and Bn (hereinafter also referred to as “image strips An and Bn”) for displaying display images A and B, respectively, are arranged side by side at corresponding positions so that the display images A and B are switched depending on a viewing angle. Note that a lenticular image  106  is constituted by the image strips An and Bn. 
     Specifically, a case where the lenticular display  100  includes the lenticular lens  104  in which, for example, N (N is an integer of 2 or more) convex lenses  102  are arranged side by side will be described. In this case, as illustrated in  FIG. 6  for example, in a region S under an n-th (n is any integer of greater than or equal to 1 and less then or equal to N) convex lens  102  counting from one end in a direction in which the convex lenses  102  are arranged side by side, an image strip An and an image strip Bn are arranged side by side to be adjacent to each other in an interlaced manner as illustrated in  FIG. 7 . The image strips An and Bn are extracted by dividing the images A and B in a stripe form. 
     As illustrated in  FIG. 8 , under the first to N-th convex lenses  102 , as in the n-th convex lens  102 , the image strips An and Bn extracted from the images A and B, respectively, are arranged side by side at corresponding positions. Furthermore, a changing effect is obtained in which, depending on an angle at which an observer views the lenticular display  100  through the lenticular lens  104 , the image A is displayed as a result of combination of the image strips An extracted from the image A, or the image B is displayed as a result of combination of the image strips Bn extracted from the image B. 
     By the way, it has been known that an afterimage is observed due to crosstalk when the image viewed by the observer is switched in the above manner. 
     Thus, a technique for reducing the afterimage is desired. For example, a technique for suppressing the crosstalk by providing a certain image between a left-eye image and a right-eye image of the lenticular image is known. As this type of technique, for example, JP1999-212024A (JP-H11-212024A) describes a technique for suppressing the generation of crosstalk by providing, in image display using the lenticular lens, a buffering region between compressed images (display image strips). The buffering region is an image having an intermediate density of the densities of the compressed images that are adjacent to each other. In addition, for example, JP2000-98948A describes a technique for arranging, in a display device for image display using a lenticular sheet, an image obtained by extracting a part with no change in image in the arrangement of the lenticular image in order to reduce the crosstalk. 
     SUMMARY 
     However, with the technique for suppressing the crosstalk by providing a certain image between the left-eye image and the right-eye image of the lenticular image, as in the techniques described in JP1999-212024A (JP-H11-212024A) and JP2000-98948A, in some cases, the crosstalk is not sufficiently suppressed, and an afterimage that interrupts viewing is generated when a viewed image is switched. 
     The present disclosure provides a lenticular display, a method for forming a lenticular image, a method for manufacturing a lenticular display, and a program for forming a lenticular image that can reduce the feeling of afterimage at the time a viewed image is switched. 
     A lenticular display according to a first aspect of the present disclosure has: a lenticular lens in which a plurality of convex lenses are arranged side by side, the plurality of convex lenses each having a convex surface; and a lenticular image provided on a back-face side facing away from the surface of the convex lenses, in which the lenticular image is a plurality of display image strips that are extracted from each of a plurality of display images in a stripe form and are arranged at corresponding positions under the convex lenses, and in which, in the plurality of display images, a color density of a portion where main-image parts overlap with each other is corrected. 
     In a lenticular display according to a second aspect of the present disclosure, in the lenticular display according to the first aspect, each of the plurality of display images may have the main image part and a background image part, and the color density of the portion where the main-image parts overlap with each other may be corrected to an intermediate color of a color of the main image part and a color of the background image part. 
     In a lenticular display according to a third aspect of the present disclosure, in the lenticular display according to the second aspect, the color density of the intermediate color may be greater than or equal to 5% and less than 50% of the color density of the background image part. 
     In a lenticular display according to a fourth aspect of the present disclosure, in the lenticular display according to any one of the first to third aspects, the main image part may include at least one of a picture or a character. 
     In addition, a method for forming a lenticular image according to a fifth aspect of the present disclosure has the steps of: correcting, for each of a plurality of display images, a color density of a portion where main-image parts overlap with each other; extracting a plurality of display image strips in a stripe form from each of the plurality of display images whose color density has been corrected; and generating image strips in which the plurality of display image strips are arranged to be adjacent to each other at corresponding positions. 
     In a method for forming a lenticular image according to a sixth aspect of the present disclosure, in the method for forming a lenticular image according to the fifth aspect, each of the plurality of display images may have the main image part and a background image part, and the color density of the portion where the main-image parts overlap with each other may be corrected to an intermediate color of a color of the main image part and a color of the background image part. 
     In a method for forming a lenticular image according to a seventh aspect of the present disclosure, in the method for forming a lenticular image according to the fifth or sixth aspect, the main image part may include at least one of a picture or a character. 
     Furthermore, a method for manufacturing a lenticular display according to an eighth aspect of the present disclosure has a step of forming a lenticular image by the method for forming a lenticular image according to any one aspect of the fifth to seventh aspects of the present disclosure on a surface of a recording medium; and a step of bonding the surface of the recording medium on which the lenticular image is formed and a back face of a lenticular lens in which a plurality of convex lenses are arranged side by side, the plurality of convex lenses each having a convex surface, the back face facing away from the surface. 
     In addition, a method for manufacturing a lenticular display according to a ninth aspect of the present disclosure has a step of forming a lenticular image by the method for forming a lenticular image according to any one aspect of the fifth to seventh aspects of the present disclosure on a back face of a lenticular lens in which a plurality of convex lenses are arranged side by side, the plurality of convex lenses each having a convex surface, the back face facing away from the surface. 
     In addition, furthermore, a program for forming a lenticular image according to a tenth aspect of the present disclosure is for causing a computer to execute: correcting, for each of a plurality of display images, a color density of a portion where main-image parts overlap with each other, extracting a plurality of display image strips in a stripe form from each of the plurality of display images whose color density has been corrected, and generating image strips in which the plurality of display image strips are arranged side by side at corresponding positions. 
     According to the present disclosure, it is possible to reduce the feeling of afterimage at the time a viewed image is switched. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments according to the technique of the present disclosure will be described in detail based on the following figures, wherein: 
         FIG. 1  is a perspective view for illustrating an example of a configuration of a lenticular display according to an embodiment; 
         FIG. 2  is an explanatory view for explaining an example of a method for forming a lenticular image according to the embodiment; 
         FIG. 3  is an explanatory view for explaining an example of display images according to the embodiment; 
         FIG. 4  is a block diagram illustrating an example of a configuration of an image forming apparatus for forming a lenticular image according to the embodiment; 
         FIG. 5  is a flowchart illustrating an example of a lenticular image forming process for forming a lenticular image according to the embodiment; 
         FIG. 6  is an explanatory view for illustrating two display images separately displayed in a lenticular display of the related art; 
         FIG. 7  is an explanatory view for illustrating image strips the region S in  FIG. 6 ; and 
         FIG. 8  is a side view for illustrating a thickness-direction configuration of the lenticular display of the related art including the image strips illustrated in  FIG. 7 . 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, examples of an embodiment for implementing the technique of the present disclosure will be described in detail with reference to drawings. 
     First, with reference to  FIGS. 1 to 3 , a configuration of a lenticular display  10  according to this embodiment will be described. Note that in  FIG. 1 , x-direction represents a width direction of the lenticular display  10 , and y-direction represents a length direction (longitudinal direction) of the lenticular display  10 . 
     As illustrated in  FIG. 1 , the lenticular display  10  includes a lenticular lens  12  and a lenticular image  14 . 
     (Configuration of Lenticular Lens) 
     As illustrated in  FIG. 1  as an example, in the lenticular lens  12  according to this embodiment, a plurality of convex lenses  12 A ( 12 A 1  to  12 AN, N is an integer of 2 or more and is 6 in the case illustrated in  FIG. 1 ) are arranged side by side. The convex lenses  12 A are each a cylindrical lens whose shape is substantially semi-cylindrical having a convex surface  12 S (top face in  FIG. 1 ) which is spherical, and a back face  12 B (bottom face in  FIG. 1 ) facing away from the surface  12 S, and are arranged side by side in the width direction (x-direction). 
     The lenticular lens  12 , that is, the convex lenses  12 A, is formed of a resin material having a light transmitting property. Examples of the resin that constitutes the lenticular lens  12  include polymethylmethacrylate (PMMA), polycarbonate, polystyrene, methacrylate-styrene copolymer (MS resin), acrylonitrile-styrene copolymer (AS resin), polypropylene, polyethylene, polyethylene terephthalate (PET), glycol-modified PET, polyvinyl chloride (PVC), thermoplastic elastomer, copolymer of these, cyclo olefin polymer, and the like. Considering the easiness of melt extrusion, for example, it is preferable to use a resin with a low melt temperature, such as PMMA, polycarbonate, polystyrene, MS resin, polyethylene, PET, or glycol-modified PET. Since a lens shape formed on a surface of an embossing roller is easily transferred and a crack is unlikely to be generated in a lens layer at the time of embossing, it is more preferable to use glycol-modified PET. The lenticular lens  12  may also be configured to include a plurality of resins. 
     A width of each of the convex lenses  12 A (lens pitch) is preferably greater than or equal to 50 μm and less than or equal to 900 μm for processability and a resolution of images. The lens pitch can be set as appropriate in accordance with the use of the lenticular display. For example, in a case where an observer observes the lenticular display by holding it, the lens pitch is preferably greater than or equal to 100 μm and less than or equal to 450 μm. This is because, in a case where the lenticular display is observed from a relatively short distance, the boundary between lenses becomes less jaggy, so that characters and the like are less difficult to read, when the lens pitch is not too large. In a case where the observer observes the lenticular display from a distant position (e.g., a distance of 50 cm or more facing the lenticular display provided on a wall or the like), the lens pitch is preferably greater than or equal to 200 μm and less than or equal to 850 μm, for example. Note that the lens pitch may be defined by LPI (Line Per Inch, the number of lenses per 1 inch (2.54 cm)) and may preferably be 100 LPI, 200 LPI, or the like, for example. In addition, on a back-face side of the convex lenses  12 A, that is, on the back face  12 B side of the lenticular lens  12 , the lenticular image  14  is provided. 
     (Configuration of Lenticular Image) 
     As illustrated in  FIG. 2  as an example, the lenticular image  14  is constituted by image strips including display image strips  14 A 1  to  14 AN and  14 B 1  to  14 BN for displaying two display images  13 A and  13 B separately. Specifically, the display image strips  14 A 1  to  14 AN and  14 B 1  to  14 BN extracted in a stripe form from the display images  13 A and  13 B, respectively, are arranged to be adjacent to each other for each of the convex lenses  12 A at corresponding positions. 
     Note that the “display image” in this embodiment means an image that is aimed to be displayed by the lenticular display  10 , that is, an image that is aimed to be recognized by an observer when the observer observes the lenticular display  10  from the lenticular lens  12  side. In addition, the “display image strip” means a rectangular image that is arranged in parallel to y-direction of the lenticular lens  12  under the lenticular lens  12  and that constitutes a part of the display images  13 A and  13 B. 
     In addition, “display image  13 ” is used for collectively referring to the display images  13 A and  13 B without distinguishing one from the other. Likewise, “display image strip  14 A” is used for collectively referring to the display image strips  14 A 1  to  14 AN without distinguishing one from another, and “display image strip  14 B” is used for collectively referring to the display image strips  14 B 1  to  14 BN without distinguishing one from another. 
       FIG. 3  illustrates an example of the display images  13 A and  13 B according to this embodiment. Note that in the example illustrated in  FIG. 3 , a case where a pictogram is a displayed image is illustrated. Note that the “pictogram” in this embodiment is an example of a “picture” in the present disclosure. As illustrated in  FIG. 3 , the display image  13 A according to this embodiment includes two main-image parts  13 Am 1  and  13 Am 2  and a single background-image part  13 Ab. In addition, the display image  13 B according to this embodiment includes two main-image parts  13 Bm 1  and  13 Bm 2  and a single background-image part  13 Bb. Note that in this embodiment, as a specific example, a case where a color of the main-image parts  13 Am 1 ,  13 Am 2 ,  13 Bm 1 , and  13 Bm 2  (hereinafter referred to as “main image color”) is white and where a color of the background-image parts  13 Ab and  13 Bb (hereinafter referred to as “background image color”) is black will be described. 
     Note that in this embodiment, the “main-image part” means a part of the display image  13  that is viewed as if being switched when an observer observes the lenticular display  10  by changing the angle. In addition, the “background-image part” means a part of the display image  13  that is viewed as not being switched when the observer observes the lenticular display  10  by changing the angle and means a part other than the main-image part in this embodiment. 
     Furthermore, as illustrated in  FIG. 3 , in the display images  13 A and  13 B according to this embodiment, a color density at a portion where the main-image parts overlap with each other is corrected. Note that in an upper drawing in  FIG. 3 , for each of the display images  13 A and  13 B, display images  113 A and  113 B before correction of the color density in the overlap portion (before color density correction) are illustrated. 
     Note that in this embodiment, the “portion where the main-image parts overlap with each other” means a portion where the main-image parts overlap when the display image  13 A and the display image  13 B overlap with each other. Note that portions where the main-image parts overlap with each other are arranged adjacent to each other in a case of constituting the lenticular image  14 . In the example illustrated in  FIG. 3 , the portion where the main-image parts overlap with each other is a portion where the main-image part  13 Am 1  and the main-image part  13 Bm 1  overlap with each other, and a portion where the main-image part  13 Am 2  and the main-image part  13 Bm 2  overlap with each other. Specifically, the portion where the main-image parts overlap with each other is an image of a portion where an arrow image that is the main-image part  13 Am 1  and an arrow image that is the main-image part  13 Bm 1  overlap with each other, and an image of a portion where a pictogram image representing an elevator that is the main-image part  13 Am 2  and a pictogram image representing stairs that is the main-image part  13 Bm 2  overlap with each other. 
     The portion where the main-image parts of the display image  13 A and the main-image parts of the display image  13 B overlap with each other is likely to be viewed as an afterimage because a color density is increased by the overlap of the main-image parts. Accordingly, in this embodiment, in order to suppress the afterimage and to make it easier to view the main-image parts even if the afterimage is generated, the color density of the portion where main-image parts of the display image  13 A and the main-image parts of the display image  13 B overlap with each other is corrected. 
     In the display images  13  according to this embodiment, the color density of the portion where the main-image part  13 Am 1  and the main-image parts  13 Bm 1  overlap with each other is corrected by using grey, which is an intermediate color of the main image color of the main-image parts  13 Am 1  and  13 Bm 1  and the background image color of the background-image parts  13 Ab and  13 Bb. In addition, in the display images  13 , the color density of the portion where the main-image part  13 Am 2  and the main-image parts  13 Bm 2  overlap with each other is corrected by using grey, which is an intermediate color of the main image color of the main-image parts  13 Am 2  and  13 Bm 2  and the background image color of the background-image parts  13 Ab and  13 Bb. 
     The lenticular image  14  according to this embodiment is formed by an image forming apparatus  30 , an example of which is illustrated in  FIG. 4 . 
     As illustrated in  FIG. 4 , the image forming apparatus  30  according to this embodiment may be a microcomputer or the like including a control unit  32 , a storage unit  34 , and an I/F (Interface) unit  36 . The control unit  32 , the storage unit  34 , and the I/F unit  36  are connected to each other via a bus  39  so that information can be mutually transferred. 
     The control unit  32  includes a CPU (Central Processing Unit)  32 A, a ROM (Read Only Memory)  32 B, and a RAM (Random Access Memory)  32 C and controls the entire image forming apparatus  30 . The CPU  32 A of the control unit  32  executes a program stored in the ROM  32 B, and thereby a lenticular image forming process, an example of which is illustrated in  FIG. 5 , is executed, and the lenticular image  14  is formed. 
     In step S 100  illustrated in  FIG. 5 , for each of the plurality of display images  13 , the control unit  32  corrects a color density of a portion where the main-image parts overlap with each other. In this embodiment, as an example, the control unit  32  first acquires the plurality of display images  13 . For example, in a case where the plurality of display images  13  are stored in the storage unit  34 , the control unit  32  acquires the plurality of display images  13  by reading them from the storage unit  34 . 
     Subsequently, from each of the plurality of display images (see display images  113 A and  113 B in  FIG. 3 ), the control unit  32  extracts main images. For example, for every predetermined region in each of the plurality of display images, the control unit  32  performs image analysis of the overlap portion and calculates a degree of similarity of the predetermined region. Subsequently, the control unit  32  extracts, as the main-image parts, predetermined regions with a degree of similarity of less than a predetermined threshold value, that is, predetermined regions with a small degree of similarity, and extracts, as the background-image parts, predetermined regions with a degree of similarity of greater than or equal to the predetermined threshold value, that is, predetermined regions with a large degree of similarity. 
     Furthermore, the control unit  32  sets the color of the portion where the extracted main-image parts overlap with each other to an intermediate color of the main image color and the background image color, and corrects the color density thereof to a color density that is determined in advance for the background-image part (specifically, greater than or equal to 5% and less than or equal to 50%, which will be described later in detail). Note that information about what colors the main image color, the background image color, and the intermediate color are may be determined in advance or may be externally acquired through the I/F unit  36 , and its acquisition method is not particularly limited. 
     Thus, the display images (see the display images  13 A and  13 B in  FIG. 3 ) in which the color density of the portion where the main-image parts overlap with each other has been corrected is generated. 
     In the subsequent step S 102 , the control unit  32  extracts, from the plurality of display images in which the color density of the portion where the main-image parts overlap with each other has been corrected, a plurality of display image strips (see the display image strips  14 A and  14 B in  FIG. 2 ) in a stripe form. The number of display image strips to be extracted is determined in accordance with the number of corresponding convex lenses  12 A of the lenticular lens  12 . 
     In the subsequent step S 104 , the control unit  32  generates image strips in which the extracted plurality of display image strips are arranged (see the lenticular image  14  in  FIG. 2 ). Thus, since the lenticular image  14  according to this embodiment has been formed, this lenticular image forming process ends. The formed lenticular image  14  is externally output through the I/F unit  36  at a predetermined timing. 
     Furthermore, the lenticular display  10  according to this embodiment can be manufactured, as an example, through steps included in the following manufacturing method. Note that the term “step” in this specification is not only an independent step. Even if a step cannot be clearly distinguished from another step, as long as an expected object of the step is achieved, the step is included in this term. 
     In a case of manufacturing the lenticular display  10 , first, as an example, the display image  13 A and the display image  13 B illustrated in  FIG. 2  are each divided into a stripe form, and the display image strips  14 A and  14 B are extracted. 
     Subsequently, the display image strips  14 A and  14 B are each printed by an ink-jet method to corresponding positions on the back face of the lenticular lens  12 , and thereby the lenticular image  14  is formed on the back face of the lenticular lens  12 . Thus, the lenticular display  10  is manufactured. Note that the method for printing the display image strips  14 A and  14 B is not limited to the ink-jet method, and an electrophotography method, an offset printing method, or the like may also be used. For example, although any of the ink-jet method and the offset printing method can be preferably used for image formation, the thickness of the lenticular display is theoretically increased as the lens pitch is increased. Thus, the ink-jet method (more preferably, flat-head method) is more preferably used than the offset printing method in some cases. 
     In addition, for example, the lenticular display  10  can be manufactured through steps included in the following manufacturing method. 
     In a case of manufacturing the lenticular display  10 , first, as an example, the display image  13 A and the display image  13 B illustrated in  FIG. 2  are each divided into a stripe form, and the display image strips  14 A and  14 B are extracted. 
     Subsequently, the display image strips  14 A and  14 B are each printed by an ink-jet method to corresponding positions on a surface of a recording medium (illustration is omitted), and thereby the lenticular image  14  is formed on the surface of the recording medium. 
     Subsequently, the surface of the recording medium on which the lenticular image  14  is formed and the back face of the lenticular lens  12  are bonded together. Thus, the lenticular display  10  is manufactured. 
     EXAMPLES 
     Hereinafter, evaluation results of the lenticular display  10  will be described by taking examples. However, the technique of the present disclosure is not limited to the following examples. 
     First Example 
     The lenticular lens  12  was formed of glycol-modified PET, and the lens pitch was set to 100 LPI. In addition, the lenticular image  14  was constituted by display image strips  14 A and  14 B obtained from two display images  13 . In addition, the main image color was white, and the background image color was black. Furthermore, a color of a portion where the main-image parts overlap with each other was grey, and its density was 15%. In addition, an image of the main-image parts was a pictogram image. 
     Second Example 
     The lenticular lens  12  was formed of glycol-modified PET, and the lens pitch was set to 100 LPI. In addition, the lenticular image  14  was constituted by display image strips  14 A and  14 B obtained from two display images  13 . In addition, the main image color was white, and the background image color was black. Furthermore, a color of a portion where the main-image parts overlap with each other was grey, and its density was 15%. In addition, an image of the main-image parts was an image representing characters. 
     Third Example 
     The lenticular lens  12  was formed of glycol-modified PET, and the lens pitch was set to 100 LPI. In addition, the lenticular image  14  was constituted by display image strips  14 A and  14 B obtained from two display images  13 . In addition, the main image color was white, and the background image color was blue. Furthermore, a color of a portion where the main-image parts overlap with each other was sky blue, and its density was 15%. In addition, the main-image parts were pictograms. 
     Fourth Example 
     The lenticular lens  12  was formed of glycol-modified PET, and the lens pitch was set to 100 LPI. In addition, the lenticular image  14  was constituted by display image strips  14 A and  14 B obtained from two display images  13 . In addition, the main image color was white, and the background image color was blue. Furthermore, a color of a portion where the main-image parts overlap with each other was sky blue, and its density was 15%. In addition, the main-image parts were characters. 
     Fifth Example 
     The lenticular lens  12  was formed of glycol-modified PET, and the lens pitch was set to 100 LPI. In addition, the lenticular image  14  was constituted by display image strips  14 A and  14 B obtained from two display images  13 . In addition, the main image color was white, and the background image color was black. Furthermore, a color of a portion where the main-image parts overlap with each other was grey, and its density was 50%. In addition, the main-image parts were pictograms. 
     Sixth Example 
     The lenticular lens  12  was formed of glycol-modified PET, and the lens pitch was set to 100 LPI. In addition, the lenticular image  14  was constituted by display image strips  14 A and  14 B obtained from two display images  13 . In addition, the main image color was white, and the background image color was black. Furthermore, a color of a portion where the main-image parts overlap with each other was grey, and its density was 5%. In addition, the main-image parts were pictograms. 
     Seventh Example 
     The lenticular lens  12  was formed of glycol-modified PET, and the lens pitch was set to 100 LPI. In addition, the lenticular image  14  was constituted by display image strips obtained from each of three display images  13 . In addition, the main image color was white, and the background image color was black. Furthermore, a color of a portion where the main-image parts overlap with each other was grey, and its density was 15%. In addition, the main-image parts were pictograms. 
     Eighth Example 
     The lenticular lens  12  was formed of acrylic, and the lens pitch was set to 100 LPI. In addition, the lenticular image  14  was constituted by display image strips  14 A and  14 B obtained from two display images  13 . In addition, the main image color was white, and the background image color was black. Furthermore, a color of a portion where the main-image parts overlap with each other was grey, and its density was 15%. In addition, the main-image parts were pictograms. 
     Ninth Example 
     The lenticular lens  12  was formed of glycol-modified PET, and the lens pitch was set to 200 LPI. In addition, the lenticular image  14  was constituted by display image strips  14 A and  14 B obtained from two display images  13 . In addition, the main image color was white, and the background image color was black. Furthermore, a color of a portion where the main-image parts overlap with each other was grey, and its density was 15%. In addition, the main-image parts were pictograms. 
     Tenth Example 
     The lenticular lens  12  was formed of glycol-modified PET, and the lens pitch was set to 100 LPI. In addition, the lenticular image  14  was constituted by display image strips  14 A and  14 B obtained from two display images  13 . In addition, the main image color was white, and the background image color was black. Furthermore, a color of a portion where the main-image parts overlap with each other was grey, and its density was 2%. In addition, the main-image parts were pictograms. 
     Eleventh Example 
     The lenticular lens  12  was formed of glycol-modified PET, and the lens pitch was set to 100 LPI. In addition, the lenticular image  14  was constituted by display image strips  14 A and  14 B obtained from two display images  13 . In addition, the main image color was white, and the background image color was black. Furthermore, a color of a portion where the main-image parts overlap with each other was grey, and its density was 60%. In addition, the main-image parts were pictograms. 
     Twelfth Example 
     The lenticular lens  12  was formed of glycol-modified PET, and the lens pitch was set to 100 LPI. In addition, the lenticular image  14  was constituted by display image strips  14 A and  14 B obtained from two display images  13 . In addition, the main image color was white, and the background image color was black. Furthermore, a color of a portion where the main-image parts overlap with each other was grey, and its density was 10%. In addition, the main-image parts were pictograms. 
     Thirteenth Example 
     The lenticular lens  12  was formed of glycol-modified PET, and the lens pitch was set to 100 LPI. In addition, the lenticular image  14  was constituted by display image strips  14 A and  14 B obtained from two display images  13 . In addition, the main image color was white, and the background image color was black. Furthermore, a color of a portion where the main-image parts overlap with each other was grey, and its density was 20%. In addition, the main-image parts were pictograms. 
     Fourteenth Example 
     The lenticular lens  12  was formed of glycol-modified PET, and the lens pitch was set to 100 LPI. In addition, the lenticular image  14  was constituted by display image strips  14 A and  14 B obtained from two display images  13 . In addition, the main image color was white, and the background image color was black. Furthermore, a color of a portion where the main-image parts overlap with each other was grey, and its density was 30%. In addition, the main-image parts were pictograms. 
     First Comparative Example 
     The lenticular lens was formed of glycol-modified PET, and the lens pitch was set to 100 LPI. In addition, the lenticular image was constituted by display image strips obtained from each of two display images. In addition, the main image color was white, and the background image color was black. Furthermore, a color of a portion where the main-image parts overlap with each other was white like the main image color, that is, the color density was not corrected, and its density was 0%. In addition, the main-image parts were pictograms. 
     Second Comparative Example 
     The lenticular lens was formed of glycol-modified PET, and the lens pitch was set to 100 LPI. In addition, the lenticular image was constituted by display image strips obtained from each of two display images. In addition, the main image color was white, and the background image color was black. Furthermore, a color of a portion where the main-image parts overlap with each other was white like the main image color, that is, the color density was not corrected, and its density was 0%. In addition, the main-image parts were characters. 
     (Evaluation Results) 
     In terms of the visibility (easiness to view) of an image depending on the generation of an afterimage, the first to fourteenth examples and the first and second comparative examples were evaluated in four grades: A to D, where grades A to C are allowable ranges as products. The evaluation results are shown in Table 1. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Lenticular Image 
                   
               
            
           
           
               
               
               
               
               
               
               
            
               
                   
                 Number 
                 Number 
                   
                 Color of 
                 Color 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Example/ 
                 Lenticular Lens 
                 (Types) 
                 (Types) 
                 Main 
                   
                 Overlap Portion 
                 Density of 
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Comparative 
                 Lens 
                 of Display 
                 of Display 
                 Image 
                 Background 
                 of Main 
                 Overlap 
                 Evaluation 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 Example 
                 Material 
                 Pitch 
                 Images 
                 Images 
                 Color 
                 Image Color 
                 Image Parts 
                 Portion (%) 
                 Visibility 
               
               
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 First Example 
                 Glycol-modified PET 
                 100 
                 Pictogram 
                 2 Types 
                 White 
                 Black 
                 Grey 
                 15 
                 A 
               
               
                 Second Example 
                 Glycol-modified PET 
                 100 
                 Character 
                 2 Types 
                 White 
                 Black 
                 Grey 
                 15 
                 A 
               
               
                 Third Example 
                 Glycol-modified PET 
                 100 
                 Pictogram 
                 2 Types 
                 White 
                 Blue 
                 Sky Blue 
                 15 
                 A 
               
               
                 Fourth Example 
                 Glycol-modified PET 
                 100 
                 Character 
                 2 Types 
                 White 
                 Blue 
                 Sky Blue 
                 15 
                 A 
               
               
                 Fifth Example 
                 Glycol-modified PET 
                 100 
                 Pictogram 
                 2 Types 
                 White 
                 Black 
                 Grey 
                 50 
                 B 
               
               
                 Sixth Example 
                 Glycol-modified PET 
                 100 
                 Pictogram 
                 2 Types 
                 White 
                 Black 
                 Grey 
                 5 
                 B 
               
               
                 Seventh Example 
                 Glycol-modified PET 
                 100 
                 Pictogram 
                 3 Types 
                 White 
                 Black 
                 Grey 
                 15 
                 A 
               
               
                 Eighth Example 
                 Acrylic 
                 100 
                 Pictogram 
                 2 Types 
                 White 
                 Black 
                 Grey 
                 15 
                 A 
               
               
                 Ninth Example 
                 Glycol-modified PET 
                 200 
                 Pictogram 
                 2 Types 
                 White 
                 Black 
                 Grey 
                 15 
                 A 
               
               
                 Tenth Example 
                 Glycol-modified PET 
                 100 
                 Pictogram 
                 2 Types 
                 White 
                 Black 
                 Grey 
                 2 
                 C 
               
               
                 Eleventh Example 
                 Glycol-modified PET 
                 100 
                 Pictogram 
                 2 Types 
                 White 
                 Black 
                 Grey 
                 60 
                 C 
               
               
                 Twelfth Example 
                 Glycol-modified PET 
                 100 
                 Pictogram 
                 2 Types 
                 White 
                 Black 
                 Grey 
                 10 
                 A 
               
               
                 Thirteenth Example 
                 Glycol-modified PET 
                 100 
                 Pictogram 
                 2 Types 
                 White 
                 Black 
                 Grey 
                 20 
                 A 
               
               
                 Fourteenth Example 
                 Glycol-modified PET 
                 100 
                 Pictogram 
                 2 Types 
                 White 
                 Black 
                 Grey 
                 30 
                 B 
               
               
                 First Comparative 
                 Glycol-modified PET 
                 100 
                 Pictogram 
                 2 Types 
                 White 
                 Black 
                 White 
                 0 
                 D 
               
               
                 Example 
               
               
                 Second Comparative 
                 Glycol-modified PET 
                 100 
                 Character 
                 2 Types 
                 White 
                 Black 
                 White 
                 0 
                 D 
               
               
                 Example 
               
               
                   
               
            
           
         
       
     
     As shown in Table 1, when the portion where the main-image parts overlap with each other was set to the intermediate color and the color density thereof was greater than or equal to 5% and less than 50% of the color density of the background-image part, preferable visibility (grade B) was obtained. In addition, when the color density of the above intermediate color was greater than or equal to 10% and less than 20% of the color density of the background-image part, more preferable visibility (grade A) was obtained. 
     On the other hand, in the first and second comparative examples in which the color density of the portion where the main-image parts overlap with each other was not corrected, the color of the overlap portion, that is, white, was viewed as being thick, and an afterimage was generated. Thus, the image visibility was decreased compared with the examples. 
     As described above, the lenticular display  10  according to this embodiment has the lenticular lens  12 , in which the plurality of convex lenses  12 A having the surface  12 S being a convex face are arranged side by side, and the lenticular image  14  provided on the back face  12 B side facing away from the surface  12 S of the convex lenses  12 A. The lenticular image  14  is the plurality of display image strips  14 A 1  to  14 AN and  14 B 1  to  14 BN extracted from the plurality of display images  13 , respectively, in a stripe form and arranged at corresponding positions under the convex lenses  12 A, and in the plurality of display images  13 , the color density of the portion where the main-image parts overlap with each other is corrected. 
     In the above manner, in the lenticular display  10  according to this embodiment, the color density of the portion where the main-image parts overlap with each other in each of the plurality of display images  13 , which is viewed as an afterimage when an image viewed by an observer is switched, is corrected to a density at which the afterimage is not viewed or to a density at which visibility is good even if the afterimage is viewed. Thus, with the lenticular display  10  according to this embodiment, the feeling of afterimage at the time a viewed image is switched can be reduced. 
     In addition, in this embodiment, the color density of the display images  13  itself is corrected and the display image strips  14 A and  14 B are extracted from the display images  13  in a stripe form, and the lenticular image  14  is formed. Subsequently, the lenticular image  14  is printed on the lenticular lens  12 , or combined by pasting together or the like, and thereby the lenticular display  10  is manufactured. Thus, for example, the method for manufacturing the lenticular display  10  becomes easy compared with a case where the crosstalk is suppressed by providing a certain image between the plurality of corresponding display image strips under each one of the convex lenses  12 A of the lenticular image. In addition, according to this embodiment, it becomes easy to increase the resolution compared with a case where a certain image is provided between the plurality of display image strips. 
     Note that although one strip of the display image strips  14 A and one strip of the display image strips  14 B are arranged under each one of the convex lenses  12 A in this embodiment, a plurality of strips of the display image strips  14 A and  14 B may be arranged under each one of the convex lenses  12 A. By increasing the number of display image strips arranged under each one of the convex lenses  12 A, the resolution can be increased. 
     In addition, although the lenticular display  10  displays two types of display images  13  ( 13 A and  13 B) in this embodiment, the lenticular display  10  may display three or more types of display images  13 . 
     In addition, although a case where the main-image part includes at least one of a pictogram or a character has been described in this embodiment, what type of image the main-image part is not particularly limited. For example, the main-image part may be a person&#39;s image in a photograph obtained by taking a person or the like. 
     In addition, although a case where the main-image part is a part of the display image  13  that is viewed as if being switched when an observer observes the lenticular display  10  by changing the angle has been described in this embodiment, the main-image part is not limited to this case. For example, in a case where there are a plurality of parts of the display image  13  that are viewed as if being switched, the main-image part may be an image including a main image therein, such as a person. 
     In addition, although a case in which the display image  13  includes the main-image part and the background-image part has been described in this embodiment, without being limited to this case, only the main-image part may be included such as in a case where the entire display image  13  is viewed as if being switched. 
     In addition, although a case where the main image color is the same in the plurality of display images  13  has been described in this embodiment, the present disclosure is not limited to this case. For example, the color of the main-image part  13 Am 1  in the display image  13 A illustrated in  FIG. 3  may be white, and the color of the main-image part  13 Bm 1  in the display image  13 B may be red. In this case, for example, on the basis of white, red, and the color of the background-image parts  13 Ab and  13 Bb, the color with which the feeling of afterimage is the weakest may be obtained through experiments to perform correction to the obtained color, or correction to an intermediate color of all of these colors or a predetermined color among these may be performed. In addition, in a case where the main-image part in each of the plurality of display images  13  includes portions whose colors are different from each other, the color density of the portions of different colors does not have to be corrected. 
     In addition, although the surface  12 S of the convex lenses  12 A is spherical in this embodiment, for example, the surface  12 S may be non-spherical as long as the surface  12 S of the convex lenses  12 A is a convex face. For example, the convex lenses  12 A may have a shape that is triangular in cross sections. 
     Besides, it is needless to say that the configuration of the lenticular display  10  and the manufacturing method thereof, the configuration of the lenticular image  14  and the manufacturing method thereof, and the like described in this embodiment are examples, and that modification can be made in accordance with the situation without departing from the spirit of the technique of the present disclosure. 
     The entire disclosure of Japanese Patent Application No. 2016-190166, filed on Sep. 28, 2016, is incorporated by reference in this specification. 
     All of the documents, patent applications, and technical standards described in this specification are incorporated by reference in this specification as well as in a case where the individual documents, patent applications, and technical standards are specifically and individually referred to as being incorporated by reference.