Abstract:
A method of generating a textured pointillist painting design comprises receiving a digital image file including a specification of a plurality of pixels representative of a digital image, the pixels each including a color definition, creating an ordered list of color definitions of the plurality of pixels in the digital image file, for each color definition in the ordered list determining a set of design parameters including: a dot size, a dot shape, a dot exclusion zone size, and a dot distribution scheme, for each color definition, determining a placement of a plurality of dots according to the pixels and color definitions in the digital image file and the set of design parameters, generating a dot list specifying the placement and design parameters of the plurality of dots representative of the digital image, and rendering on a display a facsimile image in response to the dot list.

Description:
FIELD 
     The present disclosure relates to a system and method of pointillist painting for the application of textured pigmentation to a surface. 
     RELATED PATENT APPLICATION AND PATENT 
     This patent application is related to co-pending U.S. patent application Ser. No. 13/354,934 entitled System and Method of Pointillist Painting and filed on Jan. 20, 2012. The present disclosure incorporates by reference U.S. Pat. No. 6,813,378 entitled Method for Designing Matrix Paintings and Determination of Paint Distribution issued to Randall et al. on Nov. 2, 2004 (“the &#39;378 patent”) and U.S. Pat. No. 7,094,292 entitled Mechanism for Applying Paint to Canvas issued to Randall et al. on Aug. 22, 2006 (“the &#39;292 patent”). 
     BACKGROUND 
     Pointillism is a technique of applying paint of different colors in specific patterns to form an image. The painting entitled “A Sunday Afternoon on the Island of La Grande Jatte” by George Seurat is a famous example of a pointillist painting. The artist Christian Seidler developed a pointillist painting technique called Matricism. Matricism is a technique that reduces the number of paint colors in an image by merging a distinct color design with a grayscale design. The color design has an arbitrarily small number of principle colors and the gray scale design has a limited number of values. In Matricism the number of paint colors is the product of the number of principle colors and the number of gray levels. 
     As referenced above, the &#39;378 patent describes a system for designing and processing a pointillist painting using the Matricism technique, and the &#39;292 patent describes a system for applying or depositing dots of pigmentation or paint to a surface. 
     SUMMARY 
     A method of generating a textured pointillist painting design comprises receiving a digital image file including a specification of a plurality of pixels representative of a digital image, the pixels each including a color definition, creating an ordered list of color definitions of the plurality of pixels in the digital image file, for each color definition in the ordered list determining a set of design parameters including: a dot size, a dot shape, a dot exclusion zone size, and a dot distribution scheme, for each color definition, determining a placement of a plurality of dots according to the pixels and color definitions in the digital image file and the set of design parameters, generating a dot list specifying the placement and design parameters of the plurality of dots representative of the digital image, and rendering on a display a facsimile image in response to the dot list. 
     A computerized system adapted to generate a textured pointillist painting design and implement the design comprises a display, a computer operable to: receive a digital image file including a specification of a plurality of pixels representative of a digital image, the pixels including a color definition, for each color definition in the digital image file, determining a set of design parameters including: a dot size, a three-dimensional dot shape, a dot exclusion zone size, and a dot distribution scheme, for each color definition, determining a placement of a plurality of dots according to the pixels and color definitions in the digital image file and the set of design parameters, generating a dot list specifying the placement and design parameters of the plurality of dots representative of the digital image, and rendering on a display a facsimile image in response to the dot list, and a colorant dispenser operable to apply a specified amount of a colorant to the painting surface and creating a plurality of dots having a two-dimensional coverage and three-dimensional profile at the specified placement on the painting surface in accordance with the dot list. 
     A computerized method of generating a textured pointillist painting design comprises receiving a digital image file including a specification of a plurality of pixels representative of a digital image, the pixels each including position information and color definition, for each color definition in the ordered list determining a set of design parameters for a plurality of dots, for each color definition, determining a placement of the plurality of dots according to the position information and color definitions of the plurality of pixels in the digital image file and the set of design parameters, generating a dot list specifying the placement and design parameters of the plurality of dots representative of the digital image, and rendering on a display a three-dimensional facsimile image in response to the dot list. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a simplified top view of an exemplary embodiment of a system of pointillist painting; 
         FIG. 2  is a simplified side elevational view of an exemplary embodiment of a system of pointillist painting; 
         FIG. 3  is a simplified side elevational view of an alternate exemplary embodiment of a system of pointillist painting; 
         FIG. 4  is a simplified top view of an alternate exemplary embodiment of a system of pointillist painting; 
         FIG. 5  is simplified flowchart of an exemplary method to operate a system of pointillist painting; 
         FIG. 6  shows illustrative examples of paint dot sizes from one pixel to eight pixels; 
         FIG. 7  shows illustrative examples of two paint dot sizes with respective exclusion zones; 
         FIG. 8  shows illustrative examples of an exclusion zone and it affect on paint dot placement; 
         FIG. 9  is an illustrative example of a portion of an exemplary digital color image having two colors; 
         FIG. 10  is an illustrative example of a first paint dot distribution scheme overlaid on the exemplary digital color image with two colors; 
         FIG. 11  is an illustrative example of paint dots of a first color placed according to the first paint dot distribution scheme; 
         FIG. 12  is an illustrative example of paint dots of a second color placed according to a second paint dot distribution scheme after the placement of the first color paint dots; 
         FIG. 13  is an illustrative example of a reversal of paint dot color order shown in  FIG. 12  on a white background; 
         FIG. 14  is an illustrative example of paint dot placement with the paint dots of the first color placed pursuant to a random distribution scheme; 
         FIG. 15  is an illustrative example of paint dot placement as shown in  FIG. 14  with the addition of a mask in a region of paint dots of the second color; and 
         FIG. 16  is a simplified flowchart of an exemplary method of pointillist painting design. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  are simplified top and side views of an exemplary embodiment of a system  10  of pointillist painting. System  10  employs an automated 3-D positioning system such as a gantry structure  12  that spans over a painting surface  14  such as a mounted canvas firmly supported and affixed by brackets  16 . Gantry structure  12  is operable to precisely position a colorant dispensing mechanism  18  over specific locations (X,Y) of painting surface  14  using a number of actuators and motors. Gantry structure  12  includes an X-axis actuator  20  and motor  24 , and Y-axis actuator  26  and motor  28 . Gantry structure  12  is further operable to achieve displacement of the colorant dispensing mechanism  18  along the Z-axis (the distance from painting surface  14 ) using a Z-axis actuator  30 . Accordingly, system  10  is operable to achieve precise positioning of colorant dispensing mechanism  18  over painting surface  14  in the X, Y, and Z axes. In one embodiment, the colorant dispensing mechanism is motionless while the colorant is being deposited, in another embodiment, the colorant dispensing mechanism is in motion while the colorant is being deposited. Colorant dispensing mechanism  18  is controllably operable to deposit three-dimensional dots or drops of colorant to accomplish the desired textured effect. Details of colorant dispensing mechanism  18  are described below. Although painting surface  14  is shown in the drawings as having a generally horizontal orientation, it should be noted that other orientations may be chosen. 
     It should be noted that although a gantry system is described and shown herein, the automated 3-D positioning system may be implemented in other suitable ways. For example, a robotic atm having multiple degrees of freedom may be used to properly position the colorant dispensing mechanism  18 . 
     An embodiment of colorant dispensing mechanism  18  is shown in  FIG. 2 . Colorant dispensing mechanism  18  is releasably clamped to gantry structure  12  and, similar in structure to a syringe, includes a colorant chamber  32  used to contain a desired colorant of desired color and consistency. Colorant chamber  32  is in fluid communication with a colorant dispensing tip  34  from which the colorant drop is exuded and applied to painting surface  14 . A piston  36  driven by a push rod  38  may be used to discharge the colorant onto the canvas, where push rod  38  is displaced by an actuator  40  implemented by a motor, for example. 
     Although not explicitly disclosed herein, an embodiment of colorant dispensing mechanism  18  may employ a dispensing tip in fluid communication with a remote colorant reservoir. In this embodiment, the colorant reservoir may be of a sufficient volume to store all the colorant needed of each color for the painting so that no mid-point re-loading of full syringes is necessary. 
     Because of the preferred viscosity of the colorant, the exuded drop of colorant or paint will have a two-dimensional circular coverage having a three-dimensional profile. The deposited colorant may have a profile similar to a chocolate morsel marketed and sold under the brand HERSHEY&#39;S KISSES®, or the dome atop the Taj Mahal, to name just two examples. The colorant dots with the desired 3-D profile provides a texture dimension to the resultant painting, which is strikingly distinct from paintings that are composed of two-dimensional or flat dots. 
     The actuators and motors that achieve the precise positioning of colorant dispensing mechanism  18  in the X, Y, Z axes as well as the actuation of push rod  38  are under the control of a computer system  42 , which may be implemented by a generalized computer or specialized motion control computer. Under the control of computer  42 , the actuators and motors of gantry structure  12  are instructed to position colorant dispensing tip  34  of colorant dispensing mechanism  18  at a specific location (X,Y,Z), and once positioned over the desired point and height, push rod  38  actuation is effected to exude a measured amount of colorant from dispensing tip  34 . After the application of colorant to a specific location, the Z-axis actuator  30  is activated to elevate application tip  34 , if necessary, prior to moving the colorant dispensing mechanism to avoid interfering with colorant already on the canvas. 
     Although canvas may be a common painting surface, other suitable painting surfaces or materials may be used. For example, particle board, glass, plastic, and metal materials having planar or non-planar surfaces may be incorporated herein. Further, the colorant is a general term used herein to indicate a liquid impregnated with color pigments, which may include oil, acrylic, polymer, and other types of suitable paints. It is preferable that the paint used has the proper viscosity and other characteristics to retain a three-dimensional shape after deposition on the painting surface to achieve desired textures. It is further preferable that the deposited paint can be manipulated by air blasts or other means (e.g., brush, knife, stamp, etc.) to alter its three-dimensional profile as well as its two-dimensional shape or coverage. 
       FIG. 3  is a simplified side elevational view of an alternate exemplary embodiment of a system of pointillist painting  50 , where like reference numerals are used to refer to like structures and devices shown in  FIGS. 1 and 2 . System  50  is shown to include two colorant manipulation devices  52  and  53 . Colorant manipulation devices  52  and  53  include air nozzles  54  and  55  positioned proximately to colorant dispensing tip  34 . Respective air hoses  28  and  30  couple air nozzles  54  and  55  to a pressurized air source (not shown) and where the pressurized air flow is controlled by air valves  58  and  59 . In this alternate embodiment of the system, one or more colorant manipulation devices  52  and  53  may be used to alter or manipulate the shape and/or coverage of a colorant dot immediately after depositing the colorant on the painting surface. In this example, a quick measured blast or puff of air aimed in a predefined direction may be used to achieve a particular colorant dot profile and coverage. The colorant dots of the entire painting surface may received the same uniform manipulation treatment, or alternately, selected portions of the painting surface may receive different manipulation treatment by varying the direction, amount, duration, sequence, and aperture size variables, for example, while applying the measured blast of air. Therefore, the artist is able to customize many of the colorant deposition or application design parameters to achieve the desired effect and overall look of the painting. 
       FIG. 4  is a simplified top view of yet another alternate exemplary embodiment of a system of pointillist painting  60 , where like reference numerals are used to refer to like structures and devices found in  FIGS. 1 and 2 . System  60  includes multiple gantry structures  64 ,  64 ′, and  64 ″ to achieve placement of multiple colorant dispensing mechanisms  18 ,  18 ′, and  18 ″. In this exemplary embodiment, there are three X-axis actuators  20 ,  20 ′, and  20 ″ that may operate independently in the X-axis, but their displacement in the Y-axis are in unison. Alternatively, the multiple colorant dispensing mechanisms may each have its own X and Y actuation and can move independently in both axes. As shown in  FIG. 4 , system  60  includes three gantry structures  64 ,  64 ′, and  64 ″ for the precise placement of three colorant dispensing mechanisms  18 ,  18 ′, and  18 ″, but other embodiments may be implemented as desired. The multiple colorant dispensing mechanisms may be operated in parallel for higher productivity, especially for larger painting surfaces. 
     From the foregoing, each colorant dot to be placed on a painting surface may be specified with the following design parameters: color, (X,Y) position, tip height, amount of paint to be dispensed, optional motion of the dispensing tip during deposition (starting point, end point, and travel time), height to raise the dispensing tip after deposition, and manipulation design parameters including air pressure, aperture size, angle, and duration. The design parameters may be grouped to define a “style” that the artist may store and later recall to implement on multiple paintings. 
       FIG. 5  is simplified flowchart of an exemplary method to operate a system of pointillist painting. In a preliminary step  70 , preparations are made to operate the system, including complete the painting design that specifies the positioning of dots and other additional design parameters used to achieve the desired coverage and profile (texture) of the colorant dots. The design specification is contained in a file readable and executable by computer  42 . The preparation further includes loading the colorant into the dispensing mechanism, such as filling syringes with different colors of paint that will be used for the painting, and mounting and securing the canvas in the bracket. In block  72 , the process loops over each color that will be used in the painting. In block  74 , the dispensing mechanism is loaded with one or more filled syringes, and test dots, if desired, are done at this time. In block  76 , the process loops over each dot. 
     In block  78  for each dot, the (X,Y) position and other design parameters are read from the design specification file. In some instances the proper deposition parameters are derived by look-up or another manner. In block  80 , the actuators and motors are used to move the colorant dispensing tip to the proper (X,Y) location. In block  82 , the colorant dispensing tip is lowered to the specified deposition height above the painting surface. In block  84 , the colorant dot is dispensed by actuating the push rod and piston of the dispensing mechanism. If motion during deposition is called for, the actuators and motors are effected to move the dispensing tip accordingly. In block  86 , the measured amount of colorant is applied to the painting surface and the dispensing tip is raised. In block  88 , any manipulation to modify the dot shape and profile is done, such as applying a puff of air at a specified angle and duration. In block  90 , the colorant chamber of the dispenser is checked to determine whether it is empty. If it is, the mechanism is moved to a loading position so that a filled dispenser can be loaded in block  92 . In block  94 , if there are dots of the same color left to be deposited, the process returns to block  76  for the next dot. In block  96 , if there are other paint colors to be applied, the process returns to block  72  for the next color. This process is repeated until all colors and all dots of the painting design have been deposited and the desired texture accomplished. The process ends in block  98 . 
     Changing gears, the description below is directed to the method of generating a pointillist painting design. The starting point of this method is a digital image, preferably a digital color image. Because a typical digital color image may include hundreds or thousands of colors, the image is pre-processed to reduce the number of colors to a manageable number. Existing software tools such as ADOBE® PHOTOSHOP® can be used to reassign the pixels in the digital image using only as many colors as the artist specifies. The resultant digital image is a collection of pixels, i.e., a pixel array, that is restricted to a manageable set of colors. 
       FIG. 6  shows illustrative examples of paint dot sizes from one pixel to eight pixels in diameter in the digital image. One embodiment of the method disclosed herein uses a pattern of pixels to represent a dot of a given size and shape or vice versa. The smallest dot of colorant  100  would be used to represent a single pixel. Dots  101 - 107  of larger sizes are also shown in  FIG. 6  to represent two to eight pixels in diameter in the digital image. This method allows for approximately circular colorant dots to represent square pixels in the digital image. 
     This method also introduces the concept of exclusion zones.  FIG. 7  shows illustrative examples of two paint dots  108  and  109  with respective exclusion zones  110  and  111  (shown with dashed lines). Exclusion zones  110  and  111  are situated in the center of each dot, represented by a pattern of pixels concentric with the dot. The exclusion zone of a colorant dot represents an area that cannot be shared with the exclusion zone of any other colorant dot, of any color. In other words, the exclusion zones of adjacent dots cannot overlap.  FIG. 7  shows an example of a six-pixel diameter dot  108  with a four-pixel diameter exclusion zone  110 , and a five-pixel diameter dot  109  with a seven-pixel diameter exclusion zone  111 . 
       FIG. 8  shows illustrative examples of an exclusion zone and its effect on paint dot placement. On the left is a cluster of eight five-pixel diameter dots  112  with four pixel wide exclusion zones (shown with dashed lines), and on the right is a second cluster of eight five-pixel diameter dots  114  with seven pixel wide exclusion zones. Because of the definition of the exclusion zones in terms of placement and size, the colorant dots overlap in cluster  112 , but the colorant dots do not overlap but is spaced apart in cluster  114 . 
       FIG. 9  is an illustrative example of a portion of an exemplary digital color image having two colors  116  and  118 . As shown, an exemplary grid of a single-pixel pattern is defined over the entire digital image. Grids of other sized pixels and in other orientations may be used. Over this grid, the disclosed method defines the placement of colorant dots, the sizes of the dots, and the sizes of the exclusion zones that would represent the digital color image. 
       FIG. 10  is an illustrative example of a first paint dot distribution scheme overlaid on the exemplary digital color image with two colors  116  and  118 . An array of straight single-pixel lines  120  are defined over the entire digital image. The single pixels  122  of each pixel line are spaced apart by a specified number of pixels and the lines are spaced apart by a specified number of pixels. The example in  FIG. 10  show pixel lines  120  that are five pixels apart and pixels  122  located along these lines are five pixels apart. These spacings can be defined by the artist according to his/her personal preferences. The artist may choose the spacing of the pixels and the pixel lines for the dot distribution scheme as it would be a significant factor contributing to the appearance of the painting. The defined placement of the pixels  112  on the pixel lines  120  represent the possible locations of paint dots, or the colorant dot distribution scheme. 
       FIG. 11  is an illustrative example of paint dots  124  of a first color  118  placed according to the first distribution scheme shown in  FIG. 10 . The placement of the colorant dots  124  in the design is done iteratively by the method, one after another along the pixel lines, and then completing one pixel line after another pixel line. This process is repeated until all possible locations have been examined and dots placed in the design specification when appropriate. In order to place a colorant dot in the design, the selected pixel on the line for a particular color would have to be a pixel of the same color (alternatively all of the pixels of the exclusion zone of the dot would have to be the color of the dot being placed), and all of the pixels of the exclusion zone of that dot would have to be not claimed by the exclusion zone of any other dot.  FIG. 11  shows the placement of five-pixel diameter dots of a first color  118  with three-pixel diameter exclusion zones in the design prior to the placement of colorant dots of a second color  116 . The artist may choose the order in which the colors are addressed in the design as it may be another significant factor contributing to the appearance of the painting. 
       FIG. 12  is an illustrative example of paint dots  126  of a second color  116  placed according to a second paint dot distribution scheme after the placement of the first color paint dots  124 . Although the colorant dots of the second color may be placed using the same distribution scheme as the first color dots,  FIG. 12  shows colorant dots  126  of second color  116  placed using a distribution scheme using vertical pixel lines spaced two pixels apart with potential dots spaced two-pixels apart along each line. These colorant dots  126  each have a one-pixel exclusion zone. As shown, colorant dots  126  of the second color sometimes overlap or partially cover each other and colorant dots  124  of the first color, one dot may overlap a neighboring dot&#39;s exclusion zone, however in this scheme exclusion zones may not overlap. Other rules for dot distribution and placement are possible as well. 
       FIG. 13  is an illustrative example of a reversal of paint dot color order shown in  FIG. 12 . In this example, the artist has chosen to address or assign colorant dots  124  of color  116  before colorant dots  126  of color  118  but using the same distribution schemes as in  FIG. 12 . It may be seen that changing the order in which the colors are addressed may produce a different resultant painting. 
       FIG. 14  is an illustrative example of paint dot placement with the placement of paint dots  124  of the first color assigned pursuant to a random distribution scheme. Again, the distribution scheme parameters are definable by the artist according to his/her preferences to achieve the desired result. The method further provides an artist the ability to define a style that defines a set of distribution parameters that is stored and may be recalled later for another painting. 
       FIG. 15  is an illustrative example of paint dot placement as shown in  FIG. 14  with the addition of one or more masks  128  in a selected region of colorant dots. The artist may define masks in the design to specify areas where no dots are placed. The definition of masks  128  may include the shape, dimensions, and position of the mask. 
       FIG. 16  is a simplified flowchart of an exemplary method of designing a pointillist painting. In block  130 , a digital color image is an input to the computer executing the method. As described above, the digital color image may have gone through one or more steps of pre-processing which may include reducing the colors of the digital image to a manageable set. The digital image is a definition of an array of pixels, each of which has a color assignment. In block  132 , all the pixels in the digital image are examined and the list of unique colors in the digital image are identified. Further, the number of pixels of each color is also determined. In block  134 , the list of unique colors are ordered by one of several methods automatically or selectable by the artist. This color order defines the sequence in which pixel distribution scheme of each color is determined and the colorant dot placement in the design. The exemplary methods of ordering the colors may include ordering by the value of red, green, or blue component of color, ordering by brightness, ordering by ascending or descending number of pixels of each color, and ordering by the artist&#39;s preference. In block  136 , each unique color in the digital color image is addressed in turn, including the determination of colorant dot size, dot shape, dot exclusion zone size, and dot distribution scheme(s). For each distribution scheme, the following design parameters are defined: the pixel line (horizontal, vertical, angled, straight, curved, random, etc.), pixel line spacing, start of first pixel line, and pixel spacing along the lines. The artist may choose to define multiple distribution schemes for the same color in specific regions of the painting to achieve dots of varying sizes and spacing to achieve greater varieties of textures. Each distribution scheme requires a “pass” of colorant dot placement. Further, optional mask are also defined at this point. 
     In block  138 , the colorant dot placement array is defined according to the design parameters set forth in block  136 . In block  140 , the process loops over each color in the digital image in the specified sequence to determine the dot placement arrays for all the colors in the digital image. In block  142 , the resultant placement of each colorant dot is examined to ensure that the correct color dot is placed on the correct pixel positions, and that there are no overlaps in the exclusion zones of the colorant dots. The dots that meet these criteria are collected in a dot coordinate file or list with its attendant design parameters and this process is repeated until all dots of all colors have been processed, as verified in block  144 . 
     After all of the colors in the list have been processed, the artist has the option to selectively drop one or more colors from the dot list in block  145 . For example, the artist may use a black canvas, and selectively drop black color dots from the dot list. As a result, those areas that should have been covered by black paint dots are left open to reveal the black background of the canvas. 
     In block  146 , a facsimile pointillist image of the resultant design incorporating the dots specified in the dot coordinate list is displayed on a monitor coupled to the computer as a preview, as shown in block  145 . Optionally, known 3-D CAD tools may be used to model the resultant image where each dot has the proper 3-D profile to provide the artist a more realistic rendering of the surface texture. The 3-D modeling tool may apply some simple distortion of the paint dots to mimic the effect of colorant manipulation. Alternatively, plastic deformation and fluid dynamics modeling may be used to predict the 3-D profile of the dots. The 3-D tool may permit the preview image to be seen from different perspectives, under different types of lighting, and under different lighting angles. 
     As indicated by a dashed line in  FIG. 16 , Blocks  145  and  146  may be performed as an iterative loop to permit the artist to experiment dropping different color from the dot list to see the how that affects the resultant image. 
     The artist may not like the resultant pointillist image because it did not achieve the desired effect, at which point the artist may return to block  134  to change one or more of the design parameters, such as color sequence, dot size, shape, exclusion zone size, distribution scheme, number of passes, and masks. etc. On the other hand, if the artist likes the way the facsimile looked, then in block  150 , the dot coordinate list is further processed to determine an efficient way to lay down the dots. For example, a known “travelling salesman” algorithm may be used to reduce the total distance traveled when moving from dot-to-dot in the list. The result may be a computer-readable file that is provided as an input to the computer  42  coupled to system  10 ,  50 ,  60  described above. 
     The features of the invention which are believed to be novel are set forth below with particularity in the appended claims. However, modifications, variations, and changes to the exemplary embodiments described above will be apparent to those skilled in the art, and the system and method of pointillist painting described herein thus encompasses such modifications, variations, and changes and are not limited to the specific embodiments described herein.