Patent Publication Number: US-2021187963-A1

Title: Multi-layered textured printing

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a division of U.S. patent application Ser. No. 14/548,259 filed on Nov. 19, 2014, which is incorporated herein by reference in its entirety. 
    
    
     TECHNICAL FIELD 
     The disclosure is related to ultraviolet inkjet printing, and more specifically, to printing a multi-layered textured image. 
     BACKGROUND 
     Certain types of printing systems are adapted for printing images on large-scale print media, such as for museum displays, billboards, sails, bus boards, and banners. Some of these systems use so-called drop on demand ink jet printing. In these systems, a piezoelectric vibrator applies pressure to an ink reservoir of the print head to force the ink out through the nozzle orifices positioned on the underside of the print heads. A set of print heads are typically arranged in a row along a single axis within a print head carriage. As the carriage scans back and forth along the direction of the print head axis, the print heads deposit ink across the width of the substrate. A particular image is created by controlling the order at which ink is ejected from the various nozzle orifices. 
     Some of these systems use inks with different colors to create the desired image. For instance, black, yellow, cyan, and magenta colored inks are commonly employed alone or in combination to generate the image. Thus, combinations of these four colors are used to create various other colors. Some of these printers are also used for textured printing, that is, printing images having a texture. For example, images are printed on surfaces that are rough, grainy or have a particular pattern. The current printers print textured images using techniques such as  3 D Inkjet printing with or without support material, small format multiple pass texture printing, vacuum forming after printing, texturing by casting/molding and then inkjet printing. These techniques are either slow, complicated—involves significant amount of labor, resources, etc., or expensive. 
     Further, some of these techniques use white ink or fillers to form a texture layer. Some of them form the texture using solid or composite color materials, colored binder in powder. Some of them form the texture after screen printing or inkjet printing, or print onto molded/cast texture. However, these do not provide a method for printing bas relief images. 
     SUMMARY 
     The disclosure is related to printing a multi-layered multi-pass textured image using a printing system. An image such as an image of a topographical map can be printed as a textured image, e.g., having a texture where the mountains are taller than the flat lands, desert regions are grainy, water bodies are smooth. An image can be printed with various types of texture. For example, an image of a mountain in the topographical map can be printed as a flat image, or having a particular height or having a rough surface, etc. To print an image with a particular texture, the texture can be specified using a first image file (also referred to as “texture file”), which can then be combined with a second image file (also referred to as “image file”) of the image to generate a combined file (also referred to as “textured image file”), which when input to the printing system prints the textured image. 
     The image file, the texture file and the textured image file are of a format understandable by the printing system. In some embodiments, the format understandable by the printing system is a raster transfer language (RTL) format. The RTL is a subset of the printer command language (PCL), which is a printer protocol for printing. In some embodiments, the image file and/or the texture file may not be of the RTL format, in which case they are converted to the RTL format before the textured image file is generated. Some example formats in which the image file and/or the texture file may exist include bitmap (.bmp), graphics interchange format (gif), Joint Photographic Experts Group (JPEG), tagged image file format (TIFF), portable network graphics (PNG). Further, the RTL is just one example of the format that is understandable by the printing system. The printing system can receive files of various formats other than RTL. Prior to printing the textured image, the image file and the texture file are converted to RTL files, if they are not in RTL format, and they are then processed to generate the textured image file in the RTL format. 
     The printing system prints the textured image as multi-layered and in multiple passes. The multi-layered textured image can have one or more layers of texture, one or more layers of white ink and one or more layers of the image. The higher the number of texture layers, the taller is the texture in the resulting textured image. In some embodiments, the processing of printing the multi-layered text image includes printing the texture layers first, then printing one or more white layers on the texture, and then printing the image on the white layers. The texture layers are printed using one or more colors of ink in the printing system. In some embodiments, the texture layer is coated with one or more white layers before printing the image in order to provide a bright background to the image. Since the texture layers are printed using various colors, the texture layer can be dark and if the image is printed on the dark layers, the image not be visible properly. So the texture layer is coated with one or more layers of white color and then the image is printed on the white layers. In some embodiments, if the height of the texture is higher than a specified threshold, a printing carriage of the printing system consisting of print heads that deposit the ink is raised before the next layer is printed, hence referred to as multi-pass printing. The carriage can be raised a specified number of times to accommodate taller textures. 
     In some embodiments, the image can also be printed in multiple layers. The higher the number of layers of the image, the darker and finer the image looks. The number of texture layers and/or the image layers can be specified by a user, e.g., using a printing application that is used to print the textured image. The printing application can be executing on any of the printing system or a computer connected to the printing system using which the print command is executed. The printing application includes a graphical user interface (GUI) that allows the user to select a texture, an image, specify the number of layers for the texture and/or the image, number of layers of white ink, etc. The RTL file of the textured image file includes the necessary information, e.g., above information regarding the layers, and instructions for the printing system to print the textured image accordingly. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a printing system in which a method of multi-layered textured printing of an image can be implemented. 
         FIG. 1B  is a block diagram of an environment in which the printing system of  FIG. 1  can be used to print the multi-layered textured image, consistent with various embodiments. 
         FIG. 2  is a block diagram illustrating an arrangement of print heads in a printing system of  FIG. 1 , consistent with various embodiments. 
         FIG. 3  is a block diagram depicting the underside of a print head carriage of  FIG. 2 , consistent with various embodiments. 
         FIG. 4  is a block diagram of an underside of the print head carriage of  FIG. 3  as used in a multi-channel/multi-layer mode. 
         FIG. 5  is a block diagram of the underside of the print head carriage of  FIG. 3  as used in printing in a three-layered multi-layer mode, consistent with various embodiments. 
         FIG. 6  is a block diagram illustrating printing of a multi-layered textured image using the printing system of  FIG. 1 , consistent with various embodiments. 
         FIG. 7  is a block diagram illustrating an example of the combined RTL file  625  of  FIG. 6  representing the textured image to be printed, consistent with various embodiments. 
         FIG. 8  is a block diagram illustrating a multi-layer and multi-pass printing of the textured image, consistent with various embodiments. 
         FIG. 9  is an example of a GUI of a printing application of  FIG. 1B  for generating a print job to print a multi-layered textured image, consistent with various embodiments. 
         FIG. 10  is a flow diagram illustrating a process printing a multi-layered textured image, consistent with various embodiments. 
         FIG. 11  is a flow diagram of a process for generating a print job in RTL format to print a multi-layered textured image, consistent with various embodiments. 
         FIG. 12  is a block diagram of a computer system as may be used to implement features of some embodiments of the disclosed technology. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1A  is a printing system in which the method of textured printing can be implemented. The printing system  10  includes a carriage  18  that holds a series of ink jet print heads  20  configured for printing images on a variety of substrates. Exemplary substrates include glass, wood, acrylic, and plastic substrates. The inks deposited may be solvent-based inks, or radiation (e.g., ultra-violet “UV”) curable inks. In addition to the carriage  18 , the printing system  10  includes a base  12 , a transport belt  14  that moves a substrate positioned on top of the belt  14  through the printing system  10 , and a rail system  16  attached to the base  12 . The carriage  18  is attached to a belt  22  which is wrapped around a pair of pulleys positioned on either end of the rail system  16 . 
     A carriage motor is coupled to one of the pulleys and rotates the pulley during the printing process. Accordingly, as the transport belt  14  intermittently moves the substrate, e.g., substrate  1002  of  FIG. 2 , underneath the carriage  18 , and hence the series of print heads  20 , the pulleys translate the rotary motion of the motor to a linear motion of the belt  22  thereby causing the carriage  18  to traverse back and forth along the rail system  16  across the substrate  1002  as the series of ink print heads  20  deposit ink onto the substrate  1002 . More particularly, as illustrated in  FIG. 2 , the carriage  18  moves back and forth as indicated by the arrow A as the substrate  1002  moves intermittently in the direction of arrow B underneath the print heads  20 . In some embodiments, the carriage  18  can also be raised in height to print on materials of varying thicknesses, or to accommodate textured printing. For example, if the image printed on the substrate  1002  is a textured image where the texture has a particular height, the carriage  18  can be raised to print on the raised texture. Further, the substrate  1002  can be moved in either direction—forward or backward to print in both directions. 
       FIG. 1B  is a block diagram of an environment  100  in which the printing system of  FIG. 1  can be used to print the multi-layered textured image, consistent with various embodiments. The computing device  50  includes a printing application  55  that can generate a print job, such as the print job  60 , for printing a multi-layered textured image. In some embodiments, the print job  60  is in the RTL format. The printing system  10  includes a controller  65  that controls and/or instructs the print heads  20  to print the multi-layered textured image according to the print job  60 . The printing system  10  includes a memory (not illustrated) to store the print job  60 . 
       FIG. 1B  illustrates the printing application  55  as implemented in the computing device  50 . However, it should be noted that the implementation of the printing application  55  is not limited to the above configuration. For example, a portion of the printing application  55  can be implemented in the printing system  10 . In another example, the printing application  55  can be implemented entirely in the printing system  10 . 
       FIG. 2  is a block diagram illustrating an arrangement of print heads in a printing system of  FIG. 1 , consistent with various embodiments. Print heads  20  generally include multiple groups of print heads, e.g., group  25  and group  27 , forming separate printing channels. The first group of print heads  25  forms the first printing channel and includes a series of print heads for printing multi-colored images using colored inks. In the embodiment shown in  FIG. 2 , the first group of print heads  25  includes four print heads,  25 - 1 ,  25 - 2 ,  25 - 3  and  25 - 4 , for printing black (K), yellow (Y), cyan (C), and magenta (M) inks, respectively. In practice, the first group of print heads  25  typically will include more than four print heads. For example, the first group of print heads  25  may include eight print heads, with pairs of print heads for printing each of the black (K), yellow (Y), cyan (C), and magenta (M) inks, respectively. In other embodiments, the first group of print heads  25  may include sixteen print heads, divided into sub-groups of four print heads each for printing each of the four different colored inks. 
     In some embodiments, the first group of print heads  25  may include additional print heads, or sub-sets of print heads, for depositing more than four colors. A person of ordinary skill in the art will understand that the first group of print heads  25  may include less than four print heads. In addition, a person of ordinary skill in the art will understand that the first group of print heads  25  may use less than or other than the four colors shown. 
     The second group of print heads  27 , forming the second printing channel, includes at least one print head  27 - 1  for depositing a specialized printing fluid onto the substrate  1002 . In the embodiment of  FIG. 2 , print head  27 - 1  may be used to deposit a substantially white ink (W) onto the substrate  1002 . A person of ordinary skill in the art will understand that the second group of print heads  27  may include more than one print head, e.g., two print heads for printing white ink, and may include a set of print heads for depositing a printing fluid. In addition, a person of ordinary skill in the art will understand that instead of or in addition to a substantially white ink, the second group of print heads may deposit other printing fluids and combinations of such fluids onto the substrate  1002 , such as clear protective coatings, anti-graffiti coatings, adhesives, gloss coatings, and anti-gloss coatings. 
     As shown in  FIG. 2 , the first group  25  and the second group  27  of print heads are positioned adjacent to one another in carriage  18 , and aligned along an axis “a-a” that is substantially parallel to the direction of arrow A, which is the direction of travel of the carriage  18 . The carriage  18  may also contain, or have associated with it, one or more radiation sources  28 , such as a UV lamp or a light emitting diode (“LED”) source, to partially or fully cure the inks or other printing fluids after they are deposited onto the substrate  1002 . For example, radiation source  28   a  may be located adjacent to the trailing edge of the series of print heads  20  for applying radiation to the deposited fluids as the substrate  1002  moves through the system. Similarly, radiation sources  28   b ,  28   c  may be positioned laterally adjacent to the series of print heads  20  for partially or fully curing the deposited fluids. 
     The arrangement shown in  FIG. 2  advantageously allows for sequential, multi-channel/multi-layer printing operations using a single series of print heads  20  aligned along a single print head axis “a-a.” For example, apparatus and methods in accordance with this disclosure may perform both printing texture of a textured image and an image of the textured image using the inks of the print heads  20 . Further, the texture and/or the image can be printed as a single layer or as multi-layers as described below. As described previously, the method of printing a textured image involves depositing multiple layers of ink on the substrate  1002 , which can include one or more layers of ink of specified colors for the texture, one or more layers of substantially white ink over the texture, and one or more layers of colored inks forming the image on the white ink layer. In some embodiments, one or more layers may be blank, e.g., between the texture and the white ink layer(s) and between the white ink layer(s) and the colored ink layer(s) of the image. In the blank layer, no ink is printed on the substrate  1002 . 
       FIG. 3  is a block diagram depicting the underside of a print head carriage of  FIG. 2 , consistent with various embodiments. Each of the print heads  25 - 1 ,  25 - 2 ,  25 - 3 ,  25 - 4 ,  27 - 1  includes a row of nozzles  29  running along the length of the print head. A typical print head may include a row of 256 uniformly-spaced nozzles, with a spacing of about 4/360 of an inch between adjacent nozzles. Typically, a printing system will include a set of print heads for depositing ink of each color, with each print head in the set slightly offset from the others to increase the printing system resolution. (For instance, in a system using four print heads per ink color, an offset of 1/360th of an inch between each head provides a resolution of 360 dpi). For purposes of illustration, only five print heads are shown in  FIG. 3 , one for each different color ink (i.e., W, M, C, Y, K), and each print head includes only twenty-four nozzles, e.g., nozzles  29 - 1  through  29 - 24 . 
     During a printing operation, the substrate  1002  moves under print heads in the direction of arrow B, as the carriage  18  holding the print heads scans across the substrate  1002  in the direction of arrow A. The controller  65  in the printing system  10  actuates the print heads to selectively eject ink droplets from some or all of the nozzles  29  to deposit printing fluids on the substrate  1002  in a pre-determined pattern. In some embodiments, the pattern is provided as part of an RTL file, which includes instructions for printing the texture and/or image in a format understandable by the printing system  10 . According to the present disclosure, the controller  65  is adapted to operate the printing system  10  in a multi-channel mode where the some or all of the nozzles  29  are selectively used for ejecting ink on to the substrate  1002 . The nozzles that are selected are based on the characteristics of the texture and/or the image to be printed. 
       FIG. 4  is a block diagram of an underside of the print head carriage of  FIG. 3  as used in a multi-channel/multi-layer mode. In the example of  FIG. 4 , the multi-layer mode is dual-layer, which includes printing in two layers. In some embodiments, multi-layer means number of layers of ink printed on the substrate  1002  for a given pixel of the textured image. For example, for dual-layered printing in  FIG. 4 , two layers of ink can be printed on the substrate—a first layer of ink is printed by the leading nozzles (i.e., nozzles  29 - 13  through  29 - 24 ) of one or more of the print heads  20  and another layer of ink by the trailing nozzles (i.e., nozzles  29 - 1  through  29 - 12 ) of one or more of the print heads  20 . In some embodiments, the trailing nozzles deposit the ink after the substrate  1002  is incremented by a distance d 1  (where d 1  is a length of a section of the nozzles, e.g., nozzles  29 - 13  through  29 - 24 ). 
     In this mode, as the carriage  18  scans across the substrate along the direction of arrow A, the controller  65  causes ink to eject from the nozzles of the non-hatched regions of colored ink print heads  25 - 1 ,  25 - 2 ,  25 - 3  and  25 - 4 , and white ink print head  27 , but no ink is ejected from the hatched regions of these heads. Accordingly, as the substrate moves along the direction of arrow B, it will first receive a layer of substantially white ink from the leading half of the nozzles of print head  27 . Then, as the carriage  18  scans back across the substrate  1002  and the substrate  1002  is incremented by a distance d 1  along direction of arrow B, the trailing nozzles of color ink print heads  25 - 1  through  25 - 4  print a color image over the layer of substantially white ink, while the leading nozzles of print head  27  deposit a layer of substantially white ink on the next section of the substrate  1002  to pass under the heads. This process is repeated until the entire textured image is printed, e.g., for all pixels in the entire substrate  1002 . In some embodiments, the color of the ink that should be deposited on the substrate, the nozzles that have to eject the ink are determined by the instructions in the RTL file of the textured image, which are generated based on the actual textured image. 
     It will be understood that, if necessary, a radiation source may be arranged to partially or fully cure each region of white ink and/or each region of colored inks, as they are deposited. Accordingly, the printing system  10  may simultaneously deposit both a pre-coat layer, and a color image layer on top of a pre-coat layer, using a single print head array  20  arranged along a single axis “a-a.” Note that although the above example illustrates printing one layer of white ink and another layer of colored ink over the white ink, the order of depositing the inks is not restricted to the above. The printing system  10  can be configured to print the layers in any order. In some embodiments, the RTL file of the textured image determines which colors are printed in which layer. 
     A person of ordinary skill in the art will understand that although the embodiment of  FIG. 4  shows half of the nozzles of print head  27  as performing the printing in one layer, and another half of the nozzles printing in the second layer, this exact percentage is not necessary. 
     The example of  FIG. 4  illustrates dual-layered printing. The printing system  10  can be configured to print more than two layers, e.g., three layers as described in  FIG. 5 , five layers as described with reference to  FIG. 8 , etc. The higher the number of layers, the taller the texture of the printed image. In some embodiments, to achieve multi-layered printing of a particular layer count, the nozzles of print heads  20  are segmented into as many sections as the particular count. For example, to print a three layered textured image, the nozzles of the print heads  20  are segmented into three sections, as illustrated in  FIG. 5 . 
       FIG. 5  is a block diagram of the underside of the print head carriage of  FIG. 3  as used in printing in a three-layered multi-layer mode, consistent with various embodiments. In this mode of operation, as carriage  18  scans across the substrate  1002  along the direction of arrow A, the controller  65  causes colored ink to eject from the nozzles of the non-hatched regions of color ink print heads  25 - 1 ,  25 - 2 ,  25 - 3  and  25 - 4 , and a specialized printing fluid from print head  27 , but no ink is ejected from the hatched regions of these heads. The nozzles of the print heads are segmented into three sections, e.g., the leading section (i.e., nozzles  29 - 17  through  29 - 24 ), the middle section (i.e., nozzles  29 - 9  through  29 - 16 ) and the trailing section (i.e., nozzles  29 - 1  through  29 - 8 ). Different sections eject ink in different layers. 
     For example, in a three layered textured printing of a textured image, a first layer can be the texture, a second layer can be a substantially white ink and the third layer can be the image. As the substrate  1002  moves under the carriage  18 , some or all of the color ink print heads  25  eject ink from the leading section of the nozzles forming the textured layer, then as the substrate  1002  is moved in the direction of arrow B by distance d 3 , where d 3  is a length of each section of the nozzles, the white print head deposits a second layer of white ink on the textured layer, then as the substrate  1002  is moved again by distance d 3 , some or all of the color ink print heads  25  eject ink from the trailing section of the nozzles forming the image layer. 
     This process is repeated until the entire textured image is printed, e.g., for all pixels in the entire substrate  1002 . In some embodiments, the color of the ink that should be deposited on the substrate, the nozzles that have to eject the ink in a particular layer are determined by the instructions in the RTL file of the textured image, which are generated based on the actual textured image. 
       FIG. 6  is a block diagram illustrating printing of a multi-layered textured image using the printing system of  FIG. 1 , consistent with various embodiments. The example  600  illustrates printing of a multi-layered textured image for an image represented by a source image file  615  using the texture specified in a source texture file  605 . The user may specify the source image file  615  and the source texture file  605  using the printing application  55 . The printing application  55  includes a GUI, such as the GUI  1100  of  FIG. 11  described below, for receiving the source image file  615  and the source texture file  605 . As described above, the printing application  55  can execute in any of the printing system  10  or computer connected to the printing system  10  that co-ordinates the printing of the textured image. 
     The source texture file  605  and the source image file  615  can be in a variety of formats, e.g., BMP, GIF, JPEG, TIFF, and PNG. In some embodiments, the texture can also be input to the printing application  55  as a  3 D computer aided design (CAD) style file, which is then converted to the source texture file  605  of one of the above formats. The printing application  55  converts the source texture file  605  and the source image file  615  into a format understandable by the printing system, e.g., RTL format, to generate a texture RTL file  610  and an image RTL file  620 , respectively. The printing application  55  further processes the texture RTL file  610  and an image RTL file  620  to generate a combined RTL file  625  that represents the textured image, which has multiple layers. The printing system  10  then prints the textured image on the substrate  1002  based on the combined RTL file  625 . The combined RTL file  625 , which is described in detail in the following paragraphs, can include information regarding the number of texture layers, the colors of the ink that has to be deposited in each of the texture layers, the number of white layers, the number of image layers, the order of all the layers, etc., for each pixel of the textured image. 
     In some embodiments, the source texture file  605  is a black and white or grayscale image file having intensity information, e.g., as values between 0-255, of each of the pixels of the texture. In some embodiments, the higher the intensity, the thicker or taller the texture at that particular pixel. The printing application  55  converts the source texture file  605  to the texture RTL file  610  having an ink droplet count that determines the thickness of the texture each pixel should have, and therefore the number of layers of the texture. The image RTL file  620  specifies information regarding the number of layers of the image to be printed. 
       FIG. 7  is a block diagram illustrating an example of the combined RTL file  625  of  FIG. 6  representing the textured image to be printed, consistent with various embodiments. The RTL files  610 ,  620  and  625  are generated as a function of one or more of the number of color print heads the printing system  10  has, intensity of the texture in the source texture file  605 , a desired ink droplet count for the texture and/or the image, which determines the thickness of the texture and/or the image to be printed, a number of white layers, a number of blank layers, etc. Some or all of the above values can either be specified by a user, e.g., in the GUI of the printing application, or set to default values. Further, in some embodiments, for the thickness of the texture, the user may specify the thickness in other dimensions, e.g., inch, centimeter, and the printing system can convert that into the ink droplet count, which can be based on the thickness of the ink used in the print heads. 
     For example, consider that the printing system  10  has “10” print heads; two print heads for each of W, K, Y, M, and C, color. The desired ink droplet count, that is, the maximum thickness for the texture is set to “23,” the number of white layers and blank layers are each set to “2” and the number of layers for the image is also set to “2.” 
     The printing system determines an ink droplet for a given pixel of the texture represented by the source texture file  605  as a function of the intensity of the given pixel and the desired maximum ink droplet count. The printing system obtains the intensity information of each of the pixels in the source texture file  605 , e.g., which can be in the range of 0-255 with 255 being the darkest intensity. If the intensity value of a first pixel is 255, then the texture at that first pixel is thickest, that is, the first pixel would have an ink droplet count set to the desired maximum ink droplet count “23.” The lower the intensity for a given pixel, the lower the droplet counts for the given pixel. The droplet count of “23” translates to “3” layers of texture; the printing system  10  has “10” print heads and therefore, can deposit a maximum of “10” droplets of ink for a given pixel in a single layer. So the printing system  10  prints three layers for the texture, a first layer  705  in which “10” droplets of ink are deposited, a second layer  710  in which another “10” droplets are deposited, and a third layer  715  in which the remaining “3” droplets are deposited. The colors of ink deposited in the third layer  715  for the “3” droplets can be chosen randomly, or based on user specified criteria. Accordingly, the texture RTL file  625  would have three texture layers  705 - 715  for the first pixel. 
     With reference to the image RTL file  620 , as the number of layers for the image is set to “2,” the image RTL file  620  would be split to two layers—a tenth layer  735  and eleventh layer  737 . 
     The printing application  55  processes the texture RTL file  610  and the image RTL file  620  to generate the combined RTL file  625 . In addition to the texture layers  705 - 715  and image layers  735 - 737 , the combined RTL file  625  includes the white layers  725  and  727 , and the blank layers  720 - 722  and  730 - 732 . The combined RTL file  625  also includes information regarding the order of the layers  705 - 737 , and also other instructions for printing the textured image, e.g., which section of the nozzles of the print heads should deposit ink in which layer. In some embodiments, the above process of determining the layers is repeated for all the pixels of the source image file  615  and the source texture file  605 . 
     The printing application  55  generates a count array  750  for each of the pixels in the textured image. The count array  750  includes the ink droplet count for each of the pixels, which is determined as described above. For example, the count array  750  for the first pixel includes a counter which is set to the value of the ink droplet count “23” of the first pixel. As and when the printing system  10  deposits a droplet of ink for the first pixel on the substrate  1002 , the counter is decremented by a specified value, e.g., “1”, for the first pixel. In some embodiments, depositing of a droplet of ink by a print head is considered as one count. The droplet may be deposited using one or more nozzles of the print head. When the counter of the count array  750  drops below zero, the controller  65  of the printing system  10  is notified of the completion of printing the texture layers for the first pixel. The controller  65  then prepares for printing the next type of layers for the first pixel, e.g., blank layers  720  and  722 , which can involve instructing the print heads not to print anything, and when the counter drops by two further counts indicating completion of blank layers, the controller  65  instructs the print heads of white ink to print two layers of white, and so on until the first pixel is printed completely. 
     The count array  750  helps in determining when the layer switch should be performed, e.g., from one layer to another layer such as from the first texture layer  705  to the second texture layer  710 , or from one type of layer to another type of layer such as from the texture layer to the blank layer, so that the controller  65  can instruct the print heads to deposit ink accordingly. 
     Further, the count array  750  also helps the controller  65  of the printing system  10  in determining which print heads have to deposit ink on the substrate  1002  in which layer and which nozzles of the print head have to deposit ink. For example, for the third texture layer  715 , the counter would have a value of “3,” which indicates the controller  65  to command only three print heads to deposit ink. 
     The printing application  55  inserts one or more layers of white ink between the texture and the image in order to provide a bright background for the image to be printed on the texture. Further, the printing application  55  also inserts one or more blank layers or spacers between the texture and the white layers and between the white and the image layers, e.g., to provide uniformity of the image and to minimize the spatter caused due to overspray of ink to a neighboring pixel. For example, if a white layer is immediately printed next to the texture layer on a given pixel, the pixel next to the given pixel, which is still a texture pixel can spatter onto the white and make the white less effective. By inserting one or more blank layers between different types of layers, e.g., between the white and the texture, the spatter is minimized. Further, curing techniques, such as curing using radiation sources  28  are used to cure the ink deposited on the substrate  1002 . 
     The combined RTL file  625  can also include information as the number of layers to be printed in a single pass of the substrate  1002 . In some embodiments, a pass is defined as a number of times the substrate  1002  is input to the printing system  10  to print a particular image. For example, in a two pass print, when the substrate  1002  passes under the print heads for the first time a portion of the image is printed, and when the substrate  1002  passes under the print heads for the second time, the remaining portion of the image is printed. For the second pass, the substrate  1002  is fed into the printing system  10  again. While the substrate can be fed in again, in some embodiments, the printing system  10  may not release its hold on the substrate  1002 . The printing system  10  can print one or more layers in each pass of the substrate  1002 . For example, in  FIG. 8 , the printing system  10  is configured to print five layers in some passes and in two layers in some passes. 
       FIG. 8  is a block diagram illustrating a multi-layer and multi-pass printing of the textured image, consistent with various embodiments. The printing system  10  can be configured to print in different number and/or the same number of layers in different passes of the substrate. In the example  800 , the printing system  10  is configured to print in five layers in first pass  805 , four layers in second pass  810  and in two layers in third pass  815 . For example, the printing system  10  prints the layers from the first layer  705  to the fifth layer  722  in the first pass  805 , the sixth layer  725  to ninth layer  732  in the second pass and the image layers  735  and  737  in two layers 
     In some embodiments, if the height of the texture is higher than a specified threshold, the printing carriage  18  of the printing system  10  may have to be raised before the layer is printed otherwise the print head may touch the texture. For example, if a topographic map is being printed, the mountains may get taller and the print head may touch the mountain, which obstructs the movement of the carriage and causes problem in printing. Accordingly, the carriage can be raised so that the printing system is able to continue printing the mountain. But if the carriage is raised, the other portions of the topographic map, e.g., lower surfaces may be far from the print head and the ink may not be deposited accurately when the print head sprays the ink on the lower surfaces. Accordingly, to avoid the above problem, the printing system  10  prints the lower portions of the images before the carriage  18  is raised, and when the carriage  18  is raised in the next pass, the higher portions of the textured image is printed. Thus, in some embodiments, multi-pass printing may be used to print the textured images effectively. 
     In some embodiments, the number of layers to be printed in a single pass is determined as a function of the thickness of the ink deposited and a print gap, e.g., a dimension of a gap between the print heads and the substrate  1002 . The thicker the ink is, the lesser the number of layers that can be printed in the single pass of the substrate under the print heads. Further, to achieve multi-layer printing, the nozzles of the print heads may be logically segmented in to a number of sections, as described at least with reference to  FIGS. 4 and 5 . For example, to print the five layers  705 - 722  in the first pass  805 , the controller  65  segments the nozzles of the print head  20  into five sections—a first section  851 , a second section  852 , a third section  853 , a fourth section  854  and a fifth section  855 . 
     Different sections of nozzles deposit ink in different layers. For example, when the substrate  1002  moves under the print heads in the direction of the arrow, the nozzles of one or more of the print heads in the first section  851  deposit ink on the substrate  1002 , then the substrate  1002  is moved by distance d 1  in the direction of the arrow, the nozzles of one or more of the print heads in the second section  852  deposit ink on the portion of the substrate  1002  on which the first section  851  has deposited ink, and the first section  851  deposits ink on a new portion of the substrate  1002  that comes under the print heads when the substrate  1002  was moved by distance d 1 . The distance d 1  is a length of a section of the nozzles in the first pass  805 , which is determined as a function of the number of layers to be printed in a given pass. The process of printing and moving the substrate  1002  by d 1  continues for all the remaining of the five layers of the first pixel of the textured image, and at the end of the first pass  805 , a portion of the substrate  1002  corresponding to the first pixel can have five layers of ink on it. The above process is performed for all the pixels the textured image. 
     Note that different pixels of the textured image can have different number of layers and therefore, different portions of the substrate  1002  can have different number of layers of ink at the end of first pass  805 . 
     After the first pass  805 , the carriage  18  can be raised to print the next set of layers  725 - 732  in the second pass  810 . Note that the printing system  10  is configured to print the textured image in four layers in the second pass  810 . Further, note that, as indicated by the direction of the arrow, the substrate  1002  is moving in a direction reverse to the direction it moved in the first pass  805 . In some embodiments, this minimizes the time otherwise consumed for placing the substrate  1002  in its initial position, e.g., the position at which it started in the first pass  805 , to start printing in the second pass  810 . Since the substrate is moving in the reverse direction, the layers  725 - 732  are also printed in the reverse direction. In some embodiments, the direction of movement of the substrate  1002  is the same in alternate passes. Since only four layers are printed in the second pass  810 , the nozzles are segmented into four sections, and the substrate  1002  is also moved by a distance, d 2 , equivalent to the length of a section of the nozzles in the second pass  810 , to print the layers successively. The process of printing and moving the substrate  1002  by d 2  continues for all the layers of the first pixel of the textured image, and at the end of the second pass  810 , a portion of the substrate  1002  corresponding to the first pixel can have four layers of ink on it in addition to the five layers of ink printed in the first pass  805 . 
     Note that different pixels of the textured image can have different number of layers and therefore, different portions of the substrate  1002  can have different number of layers of ink at the end of second pass  810 . 
     In the third pass  815 , the two image layers  735  and  737  are printed in two layer configuration. In some embodiments, the controller  65  prints the image layers in a separate pass and with as minimum layers as possible, e.g., in order to save time. Although the example  800  illustrates printing the image layers in a separate pass, the printing system is not restricted to printing the image layers in a separate pass. The image layers can be group with other layers in other passes. 
     Further, note that, as indicated by the direction of the arrow, the substrate  1002  is moving in a direction reverse to the direction it moved in the second pass  810 , and in the same direction as the first pass  805 . Since only two layers are printed in the third pass  815 , the nozzles are segmented into two sections, and the substrate  1002  is also moved by a distance, d 3 , equivalent to the length of a section of the nozzles in the third pass  815 , to print the layers successively. The process of printing and moving the substrate  1002  by d 3  continues for both the layers of the first pixel of the textured image, and at the end of the third pass  815 , a portion of the substrate  1002  corresponding to the first pixel can have two layers of ink on it in addition to the nine layers of ink printed in the first pass  805  and the second pass  810 . 
     Note that different pixels of the textured image can have different number of layers and therefore, different portions of the substrate  1002  can have different number of layers of ink at the end of third pass  815 . Further, if other pixels of the textured image have more layers than the first pixel, the printing may take more number of passes than depicted in example  800 . 
     In some embodiments, the combined RTL file  625  stores each of the layers as a separate job. The job includes multiple attributes that describe and/identify the job. For example the job includes a name attribute which stores the name of the job such as “Texture” “Blank” “White,” etc. and a layer attribute to indicate the layer number. In some embodiments, the name is the same for all layers, indicating that they print into the same image. A different name can indicate a different image, this is how the printing system  10  can identify all the sub-job layers that belong to the same job within the RTL that can contain multiple jobs. When the combined RTL file  625  is input to the printing system  10 , the controller  65  of the printing system  10  co-ordinates the working of the carriage  18 , the movement of the substrate  1002 , selecting a set of print heads to deposit the ink in a particular layer, selecting the set of nozzles to deposit the ink in a particular layer etc. 
       FIG. 9  is an example of a GUI of a printing application of  FIG. 1B  for generating a print job to print a multi-layered textured image, consistent with various embodiments. The printing application  55  includes a GUI  900  that allows a user to generate a print job for printing a multi-layered texture image. The user can specify the texture  907  of an image  927  by inputting a texture file representing the texture  907  using a first input field  905 . In some embodiments, the texture file is similar to the source texture file  605  of  FIG. 6 . The user can also specify the thickness of the texture using a second input field  910 . The thickness can be specified in a number of dimensions, e.g., millimeter, centimeter, and inch. In some embodiments, the thickness specified is the maximum thickness of the texture. The thickness of the texture at different pixels can be different, and is a function of the intensity information of a given pixel in the texture file. 
     The printing application  55  determines a number of ink drops required to achieve the thickness specified in the second input field  910 . In some embodiments, the number of ink drops required to achieve a particular thickness depends on the thickness of the ink used in the printing system  10 . 
     The GUI  900  allows the user to specify the number of layers of white ink to be deposited in the textured image, e.g., as described at least with reference to  FIGS. 6 and 7 , using a third input field  915 . In some embodiments, the printing application  55  can have a default value set for the number of white layers. The user can further customize this by inputting a different value. 
     The GUI  900  allows the user to specify the number of blank layers to be deposited in the textured image, e.g., as described at least with reference to  FIGS. 6 and 7 , using a fourth input field  920 . In some embodiments, the printing application  55  can have a default value set for the number of blank layers. The user can further customize this by inputting a different value in the fourth input field  920 . 
     The GUI  900  includes a fifth input field  925  using which the user can specify an image file representing the image  927  to be printed as multi-layered textured image. In some embodiments, the image file is similar to the source image file  615  of  FIG. 6 . The GUI  900  includes a sixth input field  930  using which the user can specify a number of layers in which the image  927  has to be printed. 
     The printing application  55  allows the user to generate print job, e.g., print job  60 , using the GUI element such as the button “Generate” in the GUI  900 . In some embodiments, generating the print job includes processing the texture to generate a printer executable file, e.g., texture RTL file  610 , processing the image to generate a printer executable file, e.g., image RTL file  620 , and processing the texture RTL file and the image RTL file to generate a combined RTL file  625  including instructions for printing the image as multi-layered textured image, as described at least with reference to  FIGS. 6 and 7 . 
       FIG. 10  is a flow diagram illustrating a process  1000  printing a multi-layered textured image, consistent with various embodiments. The process  1000  may be executed in the environment  100  of  FIG. 1B . At block  1005 , the printing application  55  of the computing device  50  receives a texture file that represents a texture using which an image has to be printed. In some embodiments, the texture file can be input using the GUI  900  of  FIG. 9 . 
     At block  1010 , the printing application  55  receives an image file representing the image to be printed as the multi-layered textured image. In some embodiments, the image file can be input using the GUI  900 . 
     At block  1015 , the printing application  55  receives information regarding the thickness of the texture. In some embodiments, the thickness of the texture can be input using the GUI  900 . 
     At block  1020 , the printing application  55  determines the number of layers of the texture based on the received thickness. At block  1025 , the printing application  55  generates a print job, e.g., in RTL file format, that includes instructions for printing the image as a multi-layered textured image. At block  1030 , the printing application transmits the print job to the printing system  10 , which prints the image as a multi-layered textured image on a substrate such as substrate  1002 , e.g., as described at least with reference to  FIGS. 6-8 . 
       FIG. 11  is a flow diagram of a process  1100  for generating a print job in RTL format to print a multi-layered textured image, consistent with various embodiments. The process  1100  may be executed in the environment  100  of  FIG. 1 . In some embodiments, the process  1100  describes the step  1025  of generating the print job of  FIG. 10 . At block  1105 , the printing application  55  determines for each of the pixels in the texture file the thickness of the texture to be printed on the substrate. In some embodiments, the thickness is determined as a function of the intensity information of the given pixel, e.g., as described with reference to  FIG. 7 . For example, if the maximum thickness (e.g., the thickness specified in the GUI  900 ) is one inch for a pixel with the highest intensity, then the thickness of the texture at a given pixel with 50% intensity is a determined as a 50% of maximum thickness, e.g., half inch. 
     At block  1110 , the printing application determines the thickness of the texture for each of the pixels in terms of number of ink drops required to achieve the thickness on the substrate, e.g., as described with reference to  FIG. 7 . 
     At block  1115 , the printing application determines the number of layers of the texture to be printed on the substrate for each of the pixels as a function of the number of ink drops and a number of print heads of the printing system that deposits ink on the substrate, e.g., as described with reference to  FIG. 7 . For example, if the number of ink drops required to achieve a particular thickness is “23” and the number of print heads that deposit ink in the printing system  10  is “10,” then the number of layers of the texture to be printed on the substrate is “3” (e.g., 10 print heads*1 ink drop in one layer=10 ink drops; 2 layers*10 drops each layer=20 drops; 3rd layer=3 drops—only three print heads would deposit an ink drop in the third layer). 
     At block  1120 , the printing application determines the number of layers of image to be printed on the substrate. In some embodiments, the number of layers of the image is specified using the GUI  900 . 
     At block  1125 , the printing application determines the number of layers of white ink and the number of blank layers to be printed on the substrate. In some embodiments, the number of layers of white ink and the number of blank layers are specified using the GUI  900 . 
     At block  1130 , the printing application determines the order of all layers, including layers of the texture, layers of the image, layers of white ink and the blank layers. 
     At block  1135 , the printing application generates a sub-job for each of the layers. The sub-job includes multiple attributes that identify the sub-job. For example, a sub-job includes a first attribute that identifies which print job it belongs to. The sub-job can also include a second attribute that identifies a number of the layer among all the layers. 
     At block  1140 , the sub-jobs are combined into a print job. The print job is generated in a printer executable format, e.g., RTL format. 
       FIG. 12  is a block diagram of a computer system as may be used to implement features of some embodiments of the disclosed technology. The computing system  1200  may be used to implement any of the entities, components or services depicted in the examples of  FIGS. 1-10  (and any other components described in this specification). The computing system  1200  may include one or more central processing units (“processors”)  1205 , memory  1210 , input/output devices  1225  (e.g., keyboard and pointing devices, display devices), storage devices  1220  (e.g., disk drives), and network adapters  1230  (e.g., network interfaces) that are connected to an interconnect  1215 . The interconnect  1215  is illustrated as an abstraction that represents any one or more separate physical buses, point to point connections, or both connected by appropriate bridges, adapters, or controllers. The interconnect  1215 , therefore, may include, for example, a system bus, a Peripheral Component Interconnect (PCI) bus or PCI-Express bus, a HyperTransport or industry standard architecture (ISA) bus, a small computer system interface (SCSI) bus, a universal serial bus (USB), IIC (I2C) bus, or an Institute of Electrical and Electronics Engineers (IEEE) standard 1394 bus, also called “Firewire”. 
     The memory  1210  and storage devices  1220  are computer-readable storage media that may store instructions that implement at least portions of the described technology. In addition, the data structures and message structures may be stored or transmitted via a data transmission medium, such as a signal on a communications link. Various communications links may be used, such as the Internet, a local area network, a wide area network, or a point-to-point dial-up connection. Thus, computer-readable media can include computer-readable storage media (e.g., “non-transitory” media) and computer-readable transmission media. 
     The instructions stored in memory  1210  can be implemented as software and/or firmware to program the processor(s)  1205  to carry out actions described above. In some embodiments, such software or firmware may be initially provided to the processing system  1200  by downloading it from a remote system through the computing system  1200  (e.g., via network adapter  1230 ). 
     The technology introduced herein can be implemented by, for example, programmable circuitry (e.g., one or more microprocessors) programmed with software and/or firmware, or entirely in special-purpose hardwired (non-programmable) circuitry, or in a combination of such forms. Special-purpose hardwired circuitry may be in the form of, for example, one or more ASICs, PLDs, FPGAs, etc. 
     Although the invention is described herein with reference to the preferred embodiment, one skilled in the art will readily appreciate that other applications may be substituted for those set forth herein without departing from the spirit and scope of the present invention. Accordingly, the invention should only be limited by the Claims included below.