IMAGE PROCESSING APPARATUS, INFORMATION PROCESSING APPARATUS, RECORDING METHOD, AND PROGRAM

Abstract

To record an image in which additional information is embedded such that the additional information can be read from the image recorded in an image formation member that has a plurality of coloring layers having different color development properties.SOLUTION: Recording is performed by using a print head according to recording data in an image formation member 10 that includes a plurality of coloring layers having mutually-different color development characteristics and developing colors according to applied energy. When recording the recording data in which multiplex information is embedded in image data by the print head, the multiplex information is recorded by making the coloring layer in which dots of one pixel develop a color in the shortest heating time develop colors by the print head.SELECTED DRAWING: Figure 13

Description

[Technical field]

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

[0002] Up until now, imaging using thermal printheads has been used on the market for monochrome printing using thermal paper, color printing using ink ribbons, etc. Patent Documents 1 and 2 disclose the formation of color images by applying heat to paper equipped with multiple color-forming layers. Each of the multiple color-forming layers requires different heating temperatures and heating times to develop color, and color images are formed by utilizing these differences to develop specific image-forming layers.

[0003] Furthermore, there is a technology called digital watermarking technology disclosed in Patent Documents 3 and 4, which multiplexes additional information, such as audio information or text document information, other than image information, onto an image recorded on a printout so that it is difficult to visually distinguish. The additional information is read by reading the multiplexed printout with a scanner or the like. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2013-506582 [Patent Document 2] JP 2008-030486 A [Patent Document 3] JP 2003-174556 A [Patent Document 4] JP 2004-104494 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the recording methods of Patent Documents 1 and 2, the heating temperature and heating time required for color development differ depending on the color development layer, so that even if the data has the same value, the size of the color development area differs depending on the color development layer. If additional information is embedded in an image using such a recording method as in Patent Documents 3 and 4, there is a risk that the additional information embedded in the image will not be readable.

[0006] The present invention has been made in consideration of the above-mentioned problems, and aims to record an image in which additional information is embedded so that the additional information can be read from the image recorded on an image forming member having multiple color-forming layers with different color development properties. [Means for solving the problem]

[0007] The present invention is an image forming apparatus that uses a print head that applies energy to an image forming member to form an image on an image forming member that includes a plurality of color-forming layers, each of which has different color-forming characteristics and which changes color in response to applied heat, and is equipped with a generation means that performs a multiplexing process to generate recording data in which predetermined information that is recognized by a reading device as information separate from the image is embedded in image data indicating an image to be recorded on the image forming member, and the generation means records the predetermined information by causing at least one of the plurality of color-forming layers of the image forming member that changes color to a dot of one pixel in the shortest heating time by the print head to change color, and is characterized in that, in recording the predetermined information, the generation means generates the recording data so as not to cause one of the plurality of color-forming layers of the image forming member that changes color to a dot of one pixel in the longest heating time by the print head to change color. Effect of the Invention

[0008] An image in which additional information is embedded can be recorded so that the additional information can be read out from the image recorded on an image-forming member having a plurality of color-forming layers with different color development properties. [Brief description of the drawings]

[0009] [Figure 1]FIG. 2 is a diagram for explaining a configuration of an image-forming member according to the present embodiment. [Diagram 2] FIG. 4 is a diagram for explaining the relationship between heating temperature and heating time according to the present embodiment. [Diagram 3] FIG. 2 is a diagram showing the configuration of a print head and an image forming member according to the present embodiment. [Figure 4] 1 is a diagram illustrating an example of the configuration of an image forming apparatus according to an embodiment of the present invention. [Diagram 5] FIG. 1 is a diagram for explaining the overall configuration of a system according to an embodiment of the present invention. [Figure 6] 1A to 1C are diagrams for explaining a method of forming an image including multiplexing information in the present embodiment. [Figure 7] FIG. 4 is a sequence diagram of a print service according to the embodiment. [Figure 8] 5A to 5C are diagrams illustrating examples of signal patterns applied to a print head according to the embodiment. [Figure 9] FIG. 2 is a diagram showing a mask pattern for multiplexing according to the present embodiment. [Figure 10] FIG. 2 shows a pattern provided for multiplexing according to the present embodiment. [Figure 11] FIG. 2 is a diagram showing the configuration of hardware for multiplexing decoding according to the present embodiment. [Figure 12] FIG. 2 is a diagram showing a color-developing region of an image-forming member in the present embodiment. [Figure 13] FIG. 2 is a diagram showing a color-developing region of an image-forming member in the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. Note that the configuration and the like shown below are merely examples and are not intended to be limiting.

[0011] [Image forming components] 1 is a conceptual diagram for explaining the configuration of an image forming member according to the present embodiment. In the present embodiment, an image is formed by heating the image forming member. Although a resistor is used as a heat source in the following description, other heat sources may be used, or heating may be performed using other methods, such as infrared rays.

[0012] In Fig. 1, the image forming member 10 is composed of, from the bottom layer, a light-reflecting substrate 12, an image forming layer 18, a spacer layer 17, an image forming layer 16, a spacer layer 15, an image forming layer 14, and a protective film layer 13. The image forming layers 14, 16, and 18 are generally yellow, magenta, and cyan, respectively, during full-color printing, but may be other color combinations. In other words, in the example of Fig. 1, image forming layers (color-developing layers) corresponding to three colors are provided, but more image forming layers may be provided.

[0013] Each image forming layer is initially colorless (before image formation), but changes to a corresponding color when heated to a specific temperature called the activation temperature of each image forming layer. In this embodiment, the color development characteristics for color development in each image forming layer are different. The order of colors (order of stacking) of the image forming layers in the image forming member 10 can be selected arbitrarily. One suitable color order is as described above. Another suitable order is an order in which the three image forming layers 14, 16, and 18 are cyan, magenta, and yellow, respectively. In this embodiment, an example configured in the above-mentioned order of yellow, magenta, and cyan will be used for explanation. In FIG. 1, each image forming layer is stacked to the same thickness, but this is not limited to this, and the thickness may be different depending on the color (color material).

[0014] As shown in FIG. 1, a spacer layer is provided between each of the image-forming layers. The thickness of the spacer layer may be determined according to the color development characteristics of each image-forming layer, the thermal conduction characteristics of each layer, the thermal diffusivity, and the like. For example, each spacer layer may be made of the same material or different materials. The function of the spacer layer is to control the thermal diffusion within the image-forming member 10. Preferably, when the spacer layer 17 is made of the same material as the spacer layer 15, it is at least four times thicker.

[0015] All layers disposed on substrate 12 are substantially transparent prior to imaging. If substrate 12 is a reflective color (e.g., white), the color image formed by imaging member 10 is viewed through overcoat layer 13 against the reflective background provided by substrate 12. The transparency of each layer deposited on substrate 12 allows the human eye to see the combination of colors printed on each of the imaging layers.

[0016] In this embodiment, the three image-forming layers 14, 16, and 18 in the imaging member 10 are disposed on the same side of the substrate 12, although some image-forming layers may be disposed on opposite sides of the substrate 12.

[0017] In this embodiment, the imaging layers 14, 16, and 18 are processed at least in part independently by varying two adjustable parameters in the imaging device: temperature and time. These parameters control the print head temperature and time when heat is applied to the imaging member 10 to form an image in the desired imaging layer. That is, by controlling the temperature and time applied to the imaging member 10, a desired density of color can be developed in the desired imaging layer.

[0018] In this embodiment, each of the image forming layers 14, 16, and 18 is treated by applying heat while the print head is in contact with the top layer of the image forming member 10, i.e., the protective film layer 13 shown in FIG. 1. The color development characteristics of each image forming layer according to this embodiment will be described. The activation temperatures of the image forming layers 14, 16, and 18 are Ta3, Ta2, and Ta1, respectively. In this case, the activation temperature (Ta3) of the image forming layer 14 is higher than the activation temperature (Ta2) of the image forming layer 16, and is also higher than the activation temperature (Ta1) of the first image forming layer 18. The relationship between the activation (color development characteristics) of each image forming layer will be described later with reference to FIG. 2.

[0019] Heating of the image forming layer located farther from the print head (i.e., the protective film layer 13) is delayed by the time required for heating because the heat is conducted and diffused to those layers through each spacer layer. Therefore, even if the temperature applied from the print head to the surface of the image forming member 10 (i.e., the protective film layer 13) is substantially higher than the activation temperature of the image forming layer located lower (the layer farther from the print head), the delay in heating due to the diffusion of heat through each layer makes it possible to control so that the image forming layer closer to the print head is heated to the activation temperature while the image forming layer below is not activated. Therefore, when processing (coloring) only the image forming layer 14 closest to the protective film layer 13, the print head heats up to a relatively high temperature (Ta3 or higher) in a short time. In this case, both the image forming layers 16 and 18 are insufficiently heated, and coloring (activation) of these layers is not performed.

[0020] Activation of only the imaging layer closer to substrate 12 (in this case, imaging layer 16 or 18) is accomplished by heating for a sufficiently long period of time at a temperature lower than the activation temperature of the imaging layer further from substrate 12 (e.g., imaging layer 14). In this way, when the lower imaging layer (imaging layer 16 or 18) is activated, the higher imaging layer (e.g., imaging layer 14) is not activated.

[0021] As noted above, heating of the imaging member 10 is preferably accomplished using a thermal print head, although other methods may be used, such as any known means, including a modulated light source (such as a laser).

[0022] [Color development characteristics] Figure 2 is a diagram for explaining the relationship between the heating temperature and heating time required to treat the image-forming layers 14, 16, and 18 that constitute the image-forming member 10. In Figure 2, the vertical axis indicates the heating temperature at the surface of the image-forming member 10 that contacts the print head, and the horizontal axis indicates the heating time. The heating time here will be explained as being the same as the temperature supplied by the print head.

[0023] The region 21 indicates a relatively high heating temperature and a relatively short heating time. In this embodiment, the region 21 corresponds to the yellow of the image forming layer 14. That is, when the energy shown in the region 21 is supplied to the image forming layer 14, color development (image formation) is performed. The region 22 indicates an intermediate heating temperature and an intermediate heating time. The region 22 corresponds to the magenta of the image forming layer 16. That is, when the energy shown in the region 22 is supplied to the image forming layer 16, color development (image formation) is performed. The region 23 indicates a relatively low heating temperature and a relatively long heating time. The region 22 corresponds to the cyan of the image forming layer 18. That is, when the energy shown in the region 23 is supplied to the image forming layer 18, color development (image formation) is performed. The time required for imaging (color development) of the image forming layer 18 is substantially longer than the time required for imaging the image forming layer 14.

[0024] The activation temperature selected for the imaging layers is, for example, within the range of about 90° C. to about 300° C. The activation temperature (Ta1) of the imaging layer 18 is preferably as consistently low as possible for thermal stability of the imaging member 10 during shipping and storage, and is preferably about 100° C. or higher. The activation temperature (Ta3) of the imaging layer 14 is preferably consistently high, and is preferably about 200° C. or higher, for activation of the imaging layers 16, 18 by heating through this layer. The activation temperature (Ta2) of the imaging layer 16 is between Ta1 and Ta3, and is preferably between about 140° C. to about 180° C.

[0025] In addition, even when energy is applied to each image forming layer within the corresponding region, the density of the color formed varies depending on the position within the region. For example, when energy is applied to the image forming layer 16 within the region 22, an image with a higher density is formed when a temperature closer to Ta3 is applied than when a temperature closer to Ta2 is applied, even if the heating time is the same. The same is true when the heating time varies.

[0026] [Print head] The print head of this embodiment includes a substantially linear array of resistors that extend across the width of the image. In this embodiment, the print head extends in a direction perpendicular to the transport direction of the imaging member 10 (the width of the imaging member 10), and resistors are provided along the width of the image. Note that the width of the print head may be less than the image. In such a case, the print head may be configured to move relative to the imaging member 10 to process the entire width of the image, or may be used in conjunction with other print heads.

[0027] By supplying a current to a resistor in the print head, the resistor acts as a heat source, and the image forming member 10 is conveyed while receiving heat from the resistor in the print head, so that an image is formed by each image forming layer. The time during which heat is applied to the image forming member 10 by the print head typically ranges from about 0.001 to about 100 milliseconds per line of the image. The upper limit is set in consideration of the printing time, while the lower limit is defined by the constraints of the electronic circuit (not shown). The intervals between dots forming an image are typically in the range of 100 to 600 lines per inch in both the conveying direction and the width direction of the image forming member 10, and may be different in each direction.

[0028] FIG. 3 is a diagram showing an example of the configuration of the print head and the image forming member 10 during image formation according to this embodiment. In FIG. 3(a), the image forming member 10 is transported to the right during image formation. The width direction of the image forming member 10 corresponds to the depth direction in FIG. 3(a). The print head 30 includes a glaze 32 on a base 31. In this embodiment, the glaze 32 further includes a convex glaze 33. The resistor 34 is disposed on the surface of the convex glaze 33 so as to contact the image forming member 10 transported in the transport direction. The convex glaze 33 may have another shape or may not be provided. In that case, the resistor 34 is configured to contact the image forming member 10. It is preferable that a protective film layer (not shown) is formed on the resistor 34, the glaze 32, and the convex glaze 33. The combination of the glaze 32 and the convex glaze 33, which are generally made of the same material, is hereinafter referred to as the "glaze of the print head."

[0029] A base 31 and a heat sink 35 are provided on the glaze 32. The base 31 is in contact with the heat sink 35 and is cooled by a cooling unit such as a fan (not shown). The imaging member 10 will be in contact with the print head glaze which is typically longer than the length of the actual heating resistor in the transport direction. A typical resistor has a length of about 120 microns in the transport direction of the imaging member 10, but the thermal contact area of ​​the imaging member 10 with the glaze of a typical print head will be 200 microns or more.

[0030] 3(b) is a diagram showing an example of an arrangement of resistors 34 in the width direction. A plurality of resistors 34 are arranged in the width direction, so that the resistors 34 have a fixed length in the width direction of the image forming member 10, and an image of one line is formed along this arrangement. In the example shown below, an image is formed line by line while the image forming member 10 is transported in the transport direction.

[0031] [Image forming equipment] FIG. 4 is a cross-sectional view showing an example of the configuration of the image forming apparatus according to the present embodiment. The image forming apparatus 40 includes a print head 30, a storage section 41, a conveying roller 42, a platen 43, an outlet 44, and a temperature sensor 45. The storage section 41 can store a plurality of image forming members 10, and the image forming members 10 can be replenished by opening and closing a cover (not shown). During printing, the image forming members 10 are sent to the print head 30 by the conveying roller 42, and after an image is formed between the platen 43 and the print head 30, they are discharged from the outlet 44 to complete the printing. In addition, a temperature sensor 45 is provided around the nip portion between the print head 30 and the platen 43 to detect the temperature supplied by the print head 30. The object detected by the temperature sensor 45 may be, for example, the temperature of the resistor 34 (heat source) of the print head 30, or the surface temperature of the image forming members 10. The temperature sensor 45 is not limited to a configuration that detects the temperature at only one location, but may be configured to detect the temperature at multiple locations. Furthermore, the temperature sensor 45 may be configured to detect the environmental temperature of the image forming apparatus 40.

[0032] The transport speed of the image forming member 10 is controlled according to the speed of image formation, the resolution during image formation, and the like. For example, when forming a high-resolution image, the transport speed may be slower than when forming a low-resolution image. Also, when priority is given to printing speed, the transport speed may be increased and the resolution may be decreased.

[0033] [System Configuration] Fig. 5 is a diagram showing an example of the overall configuration of a system according to this embodiment. As shown in Fig. 5, the system according to this embodiment includes the image forming apparatus 40 shown in Fig. 4 and a personal computer (PC) 50 as its host device.

[0034] The PC 50 includes a CPU (Central Processing Unit) 501, a RAM (Read Only Memory) 502, a HDD (Hard Disk Drive) 503, a communication I / F 504, an input device I / F 505, and a display device I / F, and each component is connected to each other via an internal bus so that they can communicate with each other. The CPU 501 executes processing according to programs and various data stored in the HDD 503 and RAM 502. The RAM 502 is a volatile storage device that temporarily stores programs and data. The HDD 503 is a non-volatile storage device that stores programs and data.

[0035] The communication I / F 504 is an interface that manages communication with external devices, and here controls transmission and reception of data with the image forming apparatus 40. As a connection method for transmitting and receiving data here, a wired connection such as USB, IEEE1394, LAN (Local Area Network), or a wireless connection such as Bluetooth (registered trademark), WiFi (registered trademark), etc. can be used. In this embodiment, image data to be recorded by the image forming apparatus 40 is transmitted from the PC 50 to the image forming apparatus 40 via the communication I / F 504.

[0036] The input device I / F 505 is an interface that controls a HID (Human Interface Device) such as a keyboard or a mouse, and receives input from a user's input device. The display device I / F 506 controls display on a display device such as a display (not shown).

[0037] The image forming apparatus 40 includes a CPU 401, a RAM 402, a ROM 403, a communication I / F 404, a head controller 405, an image processing accelerator 406, and a temperature sensor 45, and each component is communicably connected to each other via an internal bus. The CPU 401 executes the processes of each embodiment described later in accordance with programs and various data stored in the ROM 403 and the RAM 402. The RAM 402 is a volatile storage and temporarily stores programs and data. The ROM 403 is a non-volatile storage and stores table data and programs used in the processes described later.

[0038] The communication I / F 404 is an interface that manages communication with external devices, and in this case, controls the sending and receiving of data to and from the PC 50. The head controller 405 controls the heating operation of the head 30 shown in FIG. 3 based on the recording data. Specifically, the head controller 405 can be configured to read control parameters and recording data from a predetermined address in the RAM 402. Then, when the CPU 401 writes the control parameters and recording data to a predetermined address in the RAM 402, the head controller 405 starts processing and the heating operation of the print head 30 is performed.

[0039] The image processing accelerator 406 is configured by hardware and executes image processing faster than the CPU 401. Specifically, the image processing accelerator 406 can be configured to read parameters and data required for image processing from a predetermined address of the RAM 402. When the CPU 401 writes the parameters and data to a predetermined address of the RAM 402, the image processing accelerator 406 is started and a predetermined image processing is performed. Note that the image processing accelerator 406 is not necessarily a necessary element, and the above table parameter creation processing and image processing may be executed only by the processing by the CPU 401 according to the specifications of the printer. Also, the temperature sensor 45 detects the ambient temperature of the resistor 34 of the print head 30 as shown in FIG. 4, and provides the temperature information to the CPU 401, etc. The CPU 401 generates a control parameter for controlling the heat generation of the resistor 34 based on the acquired temperature information. Detailed control will be described later.

[0040] In this embodiment, the image forming device 40 and the PC 50 are described as different devices, but for example, they may be integrated into a system, or the image forming device 40 may be integrated into a system with an imaging device (not shown). Also, although a PC has been given as an example of the host device, this is not limiting, and for example, a mobile terminal such as a smartphone, a tablet terminal, or an imaging device may be used.

[0041] A method of forming an image including multiplexing information will be described with reference to FIG. 6. The image processing accelerator 406 has a multiplexing processing unit 407 and a recording data generating unit 408 as shown in FIG. 6. Image information A, which is information on an image to be recorded, and multiplexing information B, which is information to be embedded in an image, are input to the multiplexing unit processing 407 from the input terminal 100 and the input terminal 101, respectively. The multiplexing unit processing 407 outputs image information to which the multiplexing information has been added. The output image information to which the multiplexing information has been added is input to the recording data generating unit 408, which generates recording data indicating whether or not heating is to be performed for each pixel. The print head 30 records an image by performing a heating operation on the image forming member 10 according to the generated recording data, and outputs the image as a recorded matter C.

[0042] The multiplexing may be performed by the CPU 501 of the PC 50, or may be performed by the CPU 401 of the image forming apparatus 40. In that case, it is not necessary to have a plurality of terminals to which information is input. The multiplexing unit processing 407 will be described in detail later.

[0043] [Print service] Fig. 7 shows a sequence when a print service is performed in the system according to this embodiment. In Fig. 6, S601 to S605 show processing in the PC 50, and S611 to S616 show processing in the image forming device 40. Also, in Fig. 6, dashed arrows show data transmission and reception. Each step is realized by the CPU of each device reading and executing a program or the like stored in a storage unit. This sequence starts when a user wants to perform printing.

[0044] In S611, after the image forming apparatus 40 is powered on, it confirms that it is capable of printing and goes into a standby state, ready to provide a printing service.

[0045] On the other hand, in S601, the PC 50 executes print service discovery. The print service discovery here may be configured to search for peripheral devices according to user operations, or to periodically search for an image forming device that is in a state where it can provide a print service. Alternatively, the PC 50 may be configured to make an inquiry when the PC 50 and the image forming device 40 are connected.

[0046] In step S612, upon receiving the print service Discovery from the PC 50, the image forming apparatus 40 notifies the PC 50 in response that it is a device that can provide the print service.

[0047] In S602, when the PC 50 receives a notification from the image forming apparatus 40 that the print service can be provided, the PC 50 requests printable information from the image forming apparatus.

[0048] In step S613, the image forming apparatus 40 notifies the PC 50 of information on the printing services that the image forming apparatus 40 can provide in response to the request for printable information from the PC 50.

[0049] Upon receiving the printable information from the image forming apparatus 40, the PC 50 constructs a user interface for creating a print job based on the printable information in S603. Specifically, based on the printable information of the image forming apparatus 40, the PC 50 appropriately displays the designation of the print image, print size, printable paper size, etc., and provides appropriate options to the user via a display (not shown). Then, settings from the user are accepted via an input device (not shown) such as a keyboard.

[0050] In S604, the PC 50 issues a print job based on the settings received from the user, and transmits it to the image forming apparatus 40.

[0051] In S614, image forming apparatus 40 receives the print job from PC 50.

[0052] In S615, image forming apparatus 40 analyzes the received print job and executes printing.

[0053] When the printing is completed, in S616, the image forming apparatus 40 notifies the PC 50 of the printing completion. Then, the processing on the image forming apparatus 40 side is completed, and the image forming apparatus 40 goes into a standby state.

[0054] In S605, the PC 50 receives the print completion notification and notifies the user of the same, completing the process on the PC 50 side.

[0055] In the above description, various types of information are transmitted by making a request from the PC 50 to the image forming apparatus 40, and the image forming apparatus 40 responds to the request. However, the communication is not limited to the above-described so-called pull-type communication, and may be a so-called push-type communication in which the image forming apparatus 40 spontaneously transmits information to one or more PCs 50 on the network.

[0056] [Heating pulse] FIG. 8 shows an example of a signal pattern (heating pulse) corresponding to each color applied to the print head of the image forming apparatus. In FIG. 8, examples of colors to be developed in the image member 10 in one pixel and the configuration of the heating pulse at that time are shown. Yellow (Y), magenta (M), and cyan (C) are shown in order from the top. In FIG. 8, the heating pulse for one pixel is composed of seven sections (p0 to p6), and the length of one section is Δt0. In other words, the time of the heating pulse required to form one pixel is Δt0 × 7 sections (p0 to p6). In other words, the number of cycles of the pulse in the seven sections is used to develop the color of one pixel, and the color development is controlled by the pulse signal train included in this.

[0057] In FIG. 8, the signal shows two values, High and Low (ON and OFF). When it is High, heating is performed by the resistor 34, and when it is Low, heating is not performed. The color development is controlled by controlling the pulse width and the number of pulses contained in the heating pulse for each color. In this embodiment, the pulse width of each pulse is adjusted by PWM (Pulse Width Modulation) control. As shown in FIG. 8, the starting point of each section will be described as the rising timing (ON timing) of the pulse.

[0058] For example, when yellow (Y) is developed, heating is performed for a time period of Δt1 in order to realize the region 21 (relatively high heating temperature and relatively short heating time) shown in FIG. 2. When magenta (M) is developed, heating is performed for a time period of Δt2 twice in total with an interval in order to realize the region 22 (intermediate heating temperature and intermediate heating time) shown in FIG. 2. The interval between the first pulse and the second pulse here is (Δt0-Δt2). Similarly, when cyan (C) is developed, heating is performed for a time period of Δt3 four times in total with an interval in order to realize the region 23 (relatively low heating temperature and relatively long heating time) shown in FIG. 2. The interval between the first pulse and the second pulse here is (Δt0-Δt3). By providing this interval, the temperature of the image member 10 is prevented from rising above the target temperature (activation temperature). In other words, the target temperature is maintained by controlling the ON time and the OFF time.

[0059] In FIG. 8, for ease of understanding, Δt1=Δt2×2=Δt3×4 and the total time of the heating pulses applied to the print head 30 is the same for any color that is to be developed. t1 to t3 and Ta1 to Ta3 shown below correspond to those shown in FIG.

[0060] Heating time is t2>Y heating time Δt1>t1 t3>M heating time Δt2+Δt0>t2 Heating time of C Δt3+Δt0×3>t3 The relative relationship of the heating time is as follows: Y <M<C It is as follows.

[0061] [Multiplexing processing unit] The multiplexing unit 407 generates a multiplexed image by embedding the additional information in the image. The method of embedding information will be described with reference to Figs.

[0062] 6, image information A input from an input terminal 100 is multi-tone image data including color components. The image data is data for recording an image that will be recognized when a user views a recorded matter C when the image is output as a recorded matter C. Multiplexed information B input from an input terminal 101 is text document data, audio data, video data, or compressed data of text document information, audio information, image, video information, and other data converted into binary values. Multiplexed information B is data that is recorded so that embedded multiplexed information B is difficult to visually recognize when the image is output as a recorded matter C and viewed by a user.

[0063] The multiplexing processing unit 407 performs processing to embed the multiplexing information B in the image information A. In this embodiment, the image information A, which is RGB data transmitted from the PC 50, is converted into CMY data, which are colors that can be developed in the image forming layer, and the multiplexing information B is embedded in this CMY data. The multiplexing may be performed before the data becomes print data, and the multiplexing information may be embedded at the RBG data stage, for example.

[0064] Handling information on an information processing device such as a PC means handling binary data. Binary data is information that is either "0" or "1", and when these "0" or "1" pieces of information are connected in succession, they have a specific meaning. For example, when handling the information "hello" as binary data, in the case of "Shift JIS", one of the character codes, "h" corresponds to the binary data "01101000". Similarly, "e" corresponds to the binary data "01100101", "l" corresponds to "01101100", and "o" corresponds to the binary data "01101111". In other words, the character "hello" can be expressed in binary data as "0110100001100101011011000110110001101110001101111". Conversely, if you can obtain the binary data "0110100001100101011011000110110001101111", you can obtain the character "hello". Based on this idea, it is possible to obtain multiplexed information B by multiplexing and embedding the data so that "0" and "1" can be distinguished.

[0065] Here, two mask patterns are shown in Fig. 9(a) and (b) as masks for generating "0" and "1". The mask shown in Fig. 9 is composed of 8px x 8px, and by adding the contents of the mask to the image information A, a periodic pattern can be given to the 8px x 8px area in the image. Basically, digital images are expressed in 8 bits per color, and a value between 0 and 255 is assigned. Values ​​outside this range cannot be used as image data, so if the calculated pixel value is less than 0 or is 256 or more, it is generally assigned 0 or 255 to keep it within the valid range. In the mask in Fig. 9, the pixel value is changed by ±10, but if the image data values ​​in the mask area are all 255, the range of image data values ​​in that area will be 245 to 255, not 245 to 265. As described above, 1 bit of information can be embedded in an 8px x 8px area. When embedding multiple pieces of information, information can be embedded if there is an 8px x 8px area equal to the number of bits of the information to be embedded. The above explanation is for 8 bits per color, but it is possible to express other colors at other than 8 bits. When dealing with digital images, there is a valid range no matter how many bits are used to express them, and no changes can be made that go outside that range. Also, the area in which 1 bit of information is embedded does not have to be 8px x 8px. Also, the number of pixels in the vertical and horizontal directions does not have to be the same.

[0066] Figure 10 visually shows the type of pattern that a mask imparts to an image. In the mask in Figure 9, the "10" position is represented in black, the "0" position in gray, and the "-10" position in white, and the diagonal lines shown in Figure 10 appear in the image.

[0067] Here, pseudocode for alternately applying the masks in FIG. 9(a) and FIG. 9(b) to the entire image is shown below. ------------------------------------------------------------------ 01: int i,j,k,l; 02: int width=640,height=480; 03: unsigned char *data=image data; 04: int **maskA = mask data; 05: bool isMaskA=true; 06: for(j=0;j <height;j+=8){ 07: for(i=0;i <width;i+=8){ 08: for(k=0;k<8;k++) { 09: for(l=0;l<8;l++){ 10: if(isMaskA==true) { 11: data[(i+k)+(j+l)*width]+=maskA[k][l]; 12:} 13:} 14:} 15:} 16:} ------------------------------------------------------------------ In this way, embedding of information by multiplexing can be realized by the above method.

[0068] The image information to which the multiplexing information has been added in the above manner is image-processed by the recording data generating unit 408 to generate recording data. The print head 30 records an image on the image forming member 10 in accordance with the recording data, and outputs a recorded matter C. Looking at the pattern in FIG. 10, it can be seen that the pattern is drawn with 2px (pixel) diagonal lines. Therefore, in order to generate a recorded matter C with embedded multiplexing information using this mask, the image forming device 40 needs to be accurate enough to accurately reproduce 2px lines. If the printing resolution of the image forming device 40 is 400 dpi (px / inch), the width of the printed diagonal lines will be 2 / 400 inch.

[0069] Naturally, the image forming device 40 must have a frequency response characteristic capable of adequately reproducing the width of this oblique line. Here, the frequency response characteristic of the image forming device 40 refers to the frequency response characteristic of the images formed on the image forming layers 14, 16, and 18.

[0070] The process of generating a recorded matter C based on image data A in which multiplexing information B is embedded is also called a "multiplexing encoding process."

[0071] [Multiplexing and decoding processing section] 11 is an explanatory diagram of a configuration example of hardware (multiplexing decoding processing unit) for multiplexing decoding to extract multiplexing information B from image information recorded on a recording C. This hardware captures the multiplex-encoded recording C with an imaging device such as a camera, and extracts the multiplexing information B embedded in the image by analyzing the captured image.

[0072] In FIG. 11, a mobile terminal 1001 with a camera that holds an image sensor 1002 has a function of capturing a record C. A multiplexed information separation device 1003 extracts multiplexed information B by analyzing an image captured by the image sensor 1002, as described later. A CPU 1004 executes information processing according to a program, and a ROM 1005 stores the program executed by the CPU 1004. A RAM 1006 functions as a memory for temporarily storing various information when the CPU 1004 executes a program. A secondary storage device 1007 such as a hard disk stores image files of images captured by the image sensor 1002 and a database including image analysis results. A display 1008 presents the processing results of the CPU 1004 to a user. A key input device 1009 is a device for inputting processing instructions and characters by operating a touch panel using the display 1008 that has a touch panel function. A wireless LAN (Local Area Network) 1010 connects to the Internet, accesses a site connected to the Internet, and displays the screen of the site on a display 1008. The wireless LAN 1010 is also used for transmitting and receiving data. A speaker 1011 outputs audio when the extracted multiplexed information is audio data or audio-accompanied video data. Also, when video data is available on the Internet, audio is output when the video data is played back.

[0073] The camera-equipped mobile terminal 1001 is not limited to a configuration having a built-in imaging sensor 1002. For example, it may be configured to transmit an image captured by an imaging device other than the mobile terminal 1001 to the multiplexed information separation device 1003 of the mobile terminal 1001. A digital camera or a video camera or the like can be used as the imaging sensor 1002, and a personal computer or a smartphone or the like can be used as the multiplexed information separation device 1003, as long as it is configured to extract the multiplexed information B from the recorded matter C. In the following, the method of extracting the multiplexed information B from the recorded matter C is also referred to as a "multiplexing decoding process."

[0074] [How to print images] As explained in the paragraph [Multiplexing Encoding Processing Unit] above, in order to perform multiplexing, the image forming device 103 needs to have a frequency response characteristic that can accurately reproduce thin lines such as those shown in FIG. 10.

[0075] In thermal printing using thermal paper, as shown in FIG. 3, the heating times required to cause the image forming layers 14, 16, and 18 to develop colors differ, and therefore the frequency response characteristics differ for each image forming layer.

[0076] 12(a), (b), and (c) are diagrams of color-developing regions when the resistor 34 heats the image-forming member 10 to develop color in the image-forming layers 14, 16, and 18. The upper diagrams of FIG. 12(a) to (c) are diagrams of the image-forming device 40 viewed from the side (-X side), and the lower diagrams are diagrams of the heated image-forming member 10 viewed from above (+Z side). The crosshatched areas indicate regions to which sufficient temperature is transmitted to develop color in each image-forming layer. The color-developing regions when the image-forming layers 14, 16, and 18 are developed are 1101, 1102, and 1103, respectively. These color-developing regions are generally circular or elliptical, depending on the shape of the resistor 44.

[0077] 13(a), (b), and (c) are diagrams of coloring regions when high-frequency heating is switched on and off. FIG. 13 shows a heating state when one resistor 34 heats the image-forming member 10 three times while the image-forming member 10 is transported in the Y direction. The upper diagrams of FIG. 13(a) to (c) are diagrams of the image-forming device 40 viewed from the side (-X side), and the lower diagrams are diagrams of the heated image-forming member 10 viewed from above (+Z side). The coloring regions when the image-forming layers 14, 16, and 18 are colored at high frequency are 1201, 1202, and 1203, respectively. Looking at the coloring region 1201 when the image-forming layer 14 in FIG. 13(a) is colored, the regions that color in response to each heating are separated as in FIG. 12(a), and the image-forming layer 14 can be colored in response to high-frequency heating so that the heated region can be recognized for each pixel. The color-developing region 1202 when the image-forming layer 16 is colored, as shown in FIG. 13(b), is larger than the color-developing region 1201 when the image-forming layer 14 is colored. This is because the heating time required to color the image-forming layer 16 is longer than the heating time required to color the image-forming layer 14, so a wide range of the image-forming layer is heated. Since high-frequency heating is performed, the next pixel to be formed is close to the previously formed pixel, and a part of the image-forming layer heated to form the next pixel is already in a state of being heated when the previous pixel is formed. Since it is already in a heated state, heat is easily transmitted, and a larger range is colored than the image-forming layer 14. Therefore, the image-forming layer 16 has a smaller distance between adjacent color-developing regions than the image-forming layer 14. FIG. 13(c) is heated for an even longer time, so when printing with high frequency, it is heated almost the entire time, and the color-developing region 1203 is colored in the entire region of the image-forming layer 28 in response to high-frequency heating. In other words, the color-developing region for each pixel is not separated. Thus, the frequency response differs depending on the image-forming layer.

[0078] In conventional image forming devices, such as inkjet printers, the frequency response characteristics of the inks forming each color are almost the same and the frequency response characteristics of the inks are also high, so that the multiplexed information is embedded using inks of all colors. On the other hand, in thermal prints using thermal paper, the frequency response characteristics differ depending on the image forming layer, so if the frequency response characteristics of some colors are not sufficient for embedding the multiplexed information, the multiplexed information cannot be embedded in a readable manner.

[0079] As a solution to the above problem, in this embodiment, multiplexed information is recorded using many colors of the image-forming layer with good frequency response. By using many colors of such image-forming layers, the recording accuracy of high-frequency patterns is improved, and the multiplexed information can be read. Here, the image-forming layer with good frequency response is an image-forming layer that develops color when heated for a short time and at a high temperature, and is an image-forming layer that is shallow from the surface of the image-forming member. In the case of the image-forming member 10 of FIG. 1, the image-forming layer that develops color when heated for the shortest time, at the highest temperature, and that is shallowest from the surface of the image-forming member is the image-forming layer 14 that develops yellow.

[0080] In the above description, in Figs. 12 and 13, examples have been shown in which the coloring regions of the yellow layer and the magenta layer are separated from adjacent pixels, but as long as the multiplexed pattern can be read, the layers may not be separated from adjacent pixels. When embedding a pattern as shown in Fig. 10, in a pattern showing "0" and "1", the mask pixels of +10, +0, and -10 are separated by two pixels vertically and horizontally. It is sufficient that these lines of +10 pixels, +0 pixels, and -10 pixels are recorded so that they can be read when an image is captured. Therefore, multiplexed information cannot be embedded so as to be readable in a coloring layer that causes all of the -10 pixels two pixels adjacent to the +10 pixel to be colored when energy is applied to color the +10 pixel. When embedding a pattern as shown in Fig. 10, if the area that is colored when one pixel is to be colored is within the adjacent pixels of the target pixel, the multiplexed information can be recorded so as to be readable. For example, if the diameter of the largest dot that can fit into the area corresponding to one pixel is 1, then the diameter of the color dots in each layer is 1.5 for yellow, 2 for magenta, and 4 for cyan. The layers that can record patterns in a readable manner are the yellow and magenta color layers. Furthermore, of the two yellow and magenta color layers, the yellow color layer, which requires a shorter heating time to develop the color, can record patterns in a way that is easier to read.

[0081] An example of embedding multiplexed information in the image forming layer 14 will now be described.

[0082] In order to embed multiplexed information using the image forming layer 14 that develops color with the shortest heating time, the image data is decomposed to match the colors developed by the image forming layer. In this embodiment, the image data is decomposed into yellow, magenta, and cyan.

[0083] After decomposing into CMY components, the Y component data is changed and multiplexed. The Y component data can be changed using known methods, such as by directly adding or subtracting the mask value as shown in Figure 9, or by multiplying the mask value by a certain reference value and then performing addition or subtraction. There are no limitations on the method, as long as a pattern of "0" and "1" can be embedded in the Y component. For example, when directly adding or subtracting the mask value as shown in Figure 9, the following formula 3 is used. Formula 3: Y value after application = Y value of CMY + mask value For example, if the Y value of one pixel is "60" and the value of the mask pattern to be applied is "+10", the Y value is processed as shown in the following formula 4. Formula 4: Y value after application = 60 + (+10) Y value after application = 70 In this embodiment, the multiplexing information is embedded by changing the color of the image-forming layer 14, which develops color with the shortest heating time. However, depending on the original color of the image data to be multiplexed, the change in color of the image-forming layer 14 due to the embedding of the multiplexing information may be very noticeable.

[0084] In such cases, the colors of the other image forming layers are also changed to make the color change less noticeable. For example, if a low-brightness color is changed to yellow, the increase in brightness caused by the addition of yellow is noticeable to the human eye, making the color change more noticeable. In such cases, by changing the image values ​​of magenta and cyan in accordance with the change in yellow, the increase in brightness becomes a change in saturation, making it less noticeable to the human eye.

[0085] In addition, there may be cases where the change is less noticeable if the image forming layer 16, which is the layer that takes the second shortest time to develop color, is colored to embed the multiplexed information, rather than the image forming layer 14 being colored to embed the multiplexed information. In that case, it is also possible to color the image forming layer 16 to embed the multiplexed information. The image forming layer capable of embedding the multiplexed information is an image forming layer in which each pixel colored when printing an image is separated. In the above-mentioned image forming layers, the image forming layers 14 and 16 are capable of embedding the multiplexed information, but the image forming layer 18 is not capable of embedding the multiplexed information. The more the colored circles are separated, the easier it is to extract the multiplexed information B in the multiplexed decoding process, so it is more preferable from the viewpoint of the multiplexed decoding process to embed the multiplexed information using the image forming layer 14 rather than the image forming layer 16.

[0086] In this embodiment, the image forming layers 14, 16, and 18 are yellow, magenta, and cyan, but even if the order of these colors is reversed, the image forming layer that develops color with the shortest heating time is mainly used to embed the multiplexed information. For example, if the image forming layers 14, 16, and 18 are layers that develop magenta, cyan, and yellow, respectively, the multiplexed information is embedded using magenta.

[0087] Furthermore, the color developed by the image forming layer may be other than yellow, magenta, or cyan, for example, red, green, or blue. Even in this case, multiplexed information is embedded using the image forming layer that develops color with the shortest heating time.

[0088] In the above embodiment, the case where only the image forming layer that develops color with the shortest heating time is capable of sufficiently high-frequency color development has been described, but there may be a case where there are a plurality of image forming layers that are capable of sufficiently high-frequency color development. When a plurality of image forming layers are capable of sufficiently high-frequency color development, the embedding of multiplexed information may be performed using the plurality of image forming layers.

[0089] From the above, by embedding multiplexing information using the color of the image forming layer that develops color with the shortest heating time, it is possible to embed multiplexing information even if the frequency response characteristics of some image forming layers are not accurate enough for embedding multiplexing information.

Claims

1. An image forming apparatus for forming an image on an image forming member including a plurality of color forming layers each having different color forming characteristics and coloring in response to applied heat, using a print head that applies energy to the image forming member, comprising: a generating means for generating recording data by performing a multiplexing process, the recording data including predetermined information that is recognized by a reading device as information separate from the image, in image data representing an image to be recorded on the image forming member; The image forming apparatus is characterized in that the generation means records the specified information by causing at least one of the multiple color layers of the image forming member, which color is produced by a dot of one pixel in the shortest heating time by the print head, to color, and in recording the specified information, the generation means generates the recording data so as not to cause one of the multiple color layers of the image forming member, which color is produced by a dot of one pixel in the longest heating time by the print head, to color.

2. 2. The image forming apparatus according to claim 1, wherein the color-forming layer that develops color in the shortest time is a color-forming layer that develops yellow.

3. 3. The image forming apparatus according to claim 1, wherein the color-forming layer that develops color in the shortest time is a color-forming layer that develops color when heated to the highest temperature among the plurality of color-forming layers.

4. 4. The image forming apparatus according to claim 1, wherein the color-forming layer that develops color in the shortest time is the color-forming layer that is closest to the print head among the plurality of color-forming layers.

5. 5. The image forming apparatus according to claim 1, wherein the generating unit generates the recording data so as to record the predetermined information by causing the plurality of color-forming layers to develop colors.

6. An image forming apparatus for forming an image on an image forming member including a plurality of color forming layers each having different color forming characteristics and coloring in response to the applied energy, using a print head that applies energy to the image forming member, comprising: a generating means for generating recording data by performing a multiplexing process, the recording data including predetermined information that is recognized by a reading device as information separate from the image, in image data representing an image to be recorded on the image forming member; The generation means generates the recording data by the image forming device so that, based on the recording data, at least one of the plurality of color-forming layers is colored in a separated color-forming layer that is formed by separating a color-forming area corresponding to one pixel and a color-forming area corresponding to a pixel adjacent to the pixel when recording is performed on the image forming member by the print head, and the predetermined information is recorded, and the recording data is generated so that, in recording the predetermined information, one of the plurality of color-forming layers of the image forming member is not colored in a color-forming layer in which a color-forming area corresponding to one pixel and a color-forming area corresponding to a pixel adjacent to the pixel are not separated when energy is applied to the image forming member by the print head to record an image.

7. The image forming apparatus according to claim 6, characterized in that the separated color-forming layers for recording the specified information include a color-forming layer that develops color in the shortest time when energy is applied by the print head to cause each of the color-forming layers to develop color.

8. 8. The image forming apparatus according to claim 7, wherein the color forming layer which develops color in the shortest time is a color forming layer which develops color yellow.

9. 9. The image forming apparatus according to claim 6, wherein the generating unit generates the recording data so as to record the predetermined information by causing a plurality of the separate color-forming layers to develop colors.

10. 10. The image forming apparatus according to claim 1, wherein the generating unit generates the recording data by changing a value of the image data based on the predetermined information.

11. The image forming apparatus according to any one of claims 1 to 10, characterized in that the generating means generates the recording data so as to cause a color-forming layer other than the color-forming layer that records the specified information to develop a color based on the specified information.

12. The image data is recorded so as to be visible to a user when recorded, 12. The image forming apparatus according to claim 1, wherein the predetermined information is recorded in a manner that is difficult for a user to visually recognize when recorded.

13. 13. The image forming apparatus according to claim 1, further comprising the print head.

14. generating recording data for recording on an image forming member including a plurality of color-forming layers each having different color-forming characteristics and each of which develops a color in response to an applied energy; A recording method in which a print head applies energy to the image forming member based on the recording data to record an image, comprising: performing a multiplexing process to generate recording data in which predetermined information is embedded in image data representing an image to be recorded on the image forming member, the predetermined information being recognized by a reading device as information separate from the image; A recording method characterized in that the print head applies energy to the image forming member based on the recording data, thereby causing at least one of the multiple color layers that develops color in the shortest time to develop color, thereby recording the specified information on the image forming member, and in recording the specified information, the color layer of the multiple color layers of the image forming member that develops color in one pixel dot for the longest heating time by the print head is not caused to develop color.

15. generating recording data for recording on an image forming member including a plurality of color-forming layers each having different color-forming characteristics and each of which develops a color in response to an applied energy; A recording method in which a print head applies energy to the image forming member based on the recording data to record an image, comprising: performing a multiplexing process to generate recording data in which predetermined information that is recognized by a reading device as information separate from the image data representing the image to be recorded on the image forming member is embedded in the image data; The recording method is characterized in that, by having the print head apply energy to the image forming member based on the recording data, at least one of the multiple color-forming layers is colored in a separated color-forming layer that is formed by separating a color-forming area corresponding to one pixel and a color-forming area corresponding to a pixel adjacent to the pixel when energy is applied to the image forming member by the print head to record an image, and in recording the specified information, a color-forming layer of the multiple color-forming layers of the image forming member is not colored in which a color-forming area corresponding to one pixel and a color-forming area corresponding to a pixel adjacent to the pixel are not separated when energy is applied to the image forming member by the print head to record an image.

16. A reading method for reading an image recorded on the image-forming member by the recording method according to claim 14 or 15 with a reading device, comprising: An image recorded on the image forming member is captured by the reading device; Extracting the predetermined information embedded in the captured image from the captured image; Notifying the user of the extracted predetermined information A reading method comprising:

17. A program for causing a computer to execute a method for generating recording data to be recorded on an image forming member including a plurality of color-forming layers each having different color-forming characteristics and each of which develops a color in response to applied energy, the program comprising: performing a multiplexing process to embed predetermined information, which is recognized by a reading device as information separate from the image, into image data representing an image to be recorded on the image forming member to generate recording data; A program characterized in that, in generating the recording data, the specified information is recorded by coloring at least one of the multiple color layers, which is a separated color layer that is formed by separating a color area corresponding to one pixel and a color area corresponding to a pixel adjacent to the one pixel when recording is performed on the image forming member by a print head, based on the recording data, and in recording the specified information, the recording data is generated so that, among the multiple color layers of the image forming member, a color layer that colors a dot of one pixel for the longest heating time by the print head is not colored.

18. A program for causing a computer to execute a method for generating recording data to be recorded on an image forming member including a plurality of color-forming layers each having different color-forming characteristics and each of which develops a color in response to applied energy, the program comprising: performing a multiplexing process to embed predetermined information, which is recognized by a reading device as information separate from the image, into image data representing an image to be recorded on the image forming member to generate recording data; A program characterized in that, in generating the recording data, the specified information is recorded by coloring at least one of the multiple color-forming layers, which is a separated color-forming layer that is formed by separating a color-forming area corresponding to one pixel and a color-forming area corresponding to a pixel adjacent to the pixel when energy is applied to the image forming member by a print head to record an image, based on the recording data, and in recording the specified information, the recording data is generated so as not to color any of the multiple color-forming layers of the image forming member, which is a color-forming layer that does not separate a color-forming area corresponding to one pixel and a color-forming area corresponding to a pixel adjacent to the pixel when energy is applied to the image forming member by the print head to record an image.

Images