Patent Publication Number: US-2006007462-A1

Title: Method and apparatus for printing borderless image

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application claims the benefit under 35 U.S.C. §119(a) of Korean Patent Application No. 2004-53363, filed on Jul. 9, 2004, and Korean Patent Application No. 2004-53774 filed on Jul. 10, 2004, in the Korean Intellectual Property Office, the entire disclosures of which are hereby incorporated by reference.  
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a method and apparatus for printing an image. More particularly, the present invention relates to a method and apparatus for printing an image without borders.  
      2. Description of the Related Art  
      The popularity of digital cameras has created a need for the capability to output digital photographs, thereby resulting in the increased use of photo printers. A main function of the photo printer is to print an image without borders.  
      To print an image without borders, a user determines the size of the paper the image will be printed on and selects a borderless printing mode via a predetermined graphic user interface. When the borderless printing mode is selected, an image  120  is obtained by enlarging the size of an object image to be slightly larger than the size of the selected printing paper  10  as shown in  FIG. 1 . In other words, it is possible to print an object image without borders by enlarging the object image to be larger than the printing paper and printing the enlarged image on the printing paper.  
      Conventionally, in order to print an image without borders, an object image is enlarged to be slightly larger than the size of the printing paper using an image enlargement method. There are various ways of enlarging an image. If the image is enlarged to obtain a high-quality image, the quality of the image is satisfactory but a large amount of computation is required to obtain the values of the generated pixels. However, if the image is enlarged to obtain a low-quality image, the values of the generated pixels can be quickly and easily computed. That is, there is a trade-off between the quality of enlarged image and the speed at which the enlarged image is processed.  
      In general, in the case of an image, such as a photograph, where the eyes of a viewer are focused on the center of the image, the focus of the image is likely to be set to the center of image. Accordingly, there is a need to develop a method and apparatus for dividing an image that is to be printed into several regions, enlarging the regions using different image enlargement methods, and printing the enlarged regions of the image.  
      Also, needed is a method for printing an image without borders comprising the steps of selecting an image enlargement method selected in consideration of the characteristics of the printing paper on which an image is to be printed, enlarging the image using the selected image enlargement method, and printing the enlarged image.  
     SUMMARY OF THE INVENTION  
      The present invention provides a method and apparatus for printing an image without borders by dividing the image into at least two regions and enlarging the two regions using different image enlargement methods.  
      The present invention also provides a method and apparatus for printing an image without borders by enlarging the image using an image enlargement method selected in consideration of a desired quality of the image to be obtained.  
      The present invention also provides a method and apparatus for printing an image without borders by enlarging the image using an image enlargement method selected in consideration of a desired quality of image to be obtained and the type of printing paper on which the image will be printed.  
      According to one aspect of the present invention, there is provided an apparatus for printing an image without borders on printing paper, the apparatus comprising an image division unit for dividing the image into image regions with predetermined sizes according to a predetermined pattern; an image expansion unit for obtaining an expanded image by computing the values of the expansion pixels of the image regions using image expansion methods corresponding to the respective image regions; and a printing unit for printing the expanded image.  
      The apparatus may further comprise a division region selector for selecting the pattern and sizes of the image regions into which the image is divided.  
      The apparatus may further comprise an image expansion method selector for selecting the image expansion methods by which the respective image regions are expanded from a plurality of image expansion methods.  
      The image expansion unit can include a searching unit for searching for the expansion pixels from the image regions, and a calculator for calculating the values of the expansion pixels according to the image expansion methods matching the respective image regions.  
      According to another aspect of the present invention, there is provided a method for printing an image without borders on printing paper, the method comprising the steps of dividing the image into at least two image regions, obtaining an expanded image by computing the values of the expansion pixels of the image regions according to image expansion methods matching the respective image regions, and printing the expanded image.  
      According to yet another aspect of the present invention, there is provided a method for printing an image without borders comprising the steps of selecting a print mode according to print quality in response to a user command, enlarging the image using an image expansion method corresponding to the selected print mode, and printing the enlarged image.  
      According to still another aspect of the present invention, there is provided a method of printing an image without borders comprising the steps of selecting a print mode according to print quality in response to a user command, selecting a print mode according to the type of printing paper in response to a user command, enlarging the image using an image expansion method corresponding the print modes selected according to the print quality and the type of printing paper, and printing the enlarged image.  
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above and other aspects and advantages of the present invention will become more apparent by describing in detail exemplary embodiments thereof with reference to the attached drawings in which:  
       FIG. 1  illustrates the outlines of an image and a print medium on which the image is printed in a borderless image printing mode in which an image is printed without borders;  
       FIG. 2  is a block diagram of an apparatus for printing an image without borders according to an embodiment of the present invention;  
       FIGS. 3A and 3B  illustrate the patterns and sizes of regions into which an input image is divided according to an embodiment of the present invention;  
       FIG. 4  is a flowchart illustrating a method for printing an image without borders according to an embodiment of the present invention;  
       FIG. 5  is a flowchart illustrating a method for printing an image without borders according to another embodiment of the present invention;  
       FIGS. 6A through 6C  are flowcharts illustrating methods of enlarging image regions into which an image is divided according to embodiments of the present invention;  
       FIG. 7  is a block diagram of an apparatus for printing an image without borders according to another embodiment of the present invention;  
       FIG. 8  is a block diagram of a print mode selector of the apparatus of  FIG. 7  according to an embodiment of the present invention;  
       FIG. 9  is a block diagram of a print mode selector of the apparatus of  FIG. 7  according to another embodiment of the present invention;  
       FIG. 10  is a flowchart illustrating a method of printing an image without borders according to an embodiment of the present invention;  
       FIG. 11  is a flowchart illustrating a method of printing an image without borders according to another embodiment of the present invention;  
       FIG. 12A  is a flowchart illustrating a method of enlarging an image according to a print mode selected for print quality to be obtained and the type of printing paper according to an embodiment of the present invention; and  
       FIG. 12B  is a flowchart illustrating a method of enlarging an image according to a print mode selected for print quality to be obtained and the type of printing paper according to another embodiment of the present invention.  
    
    
      Throughout the drawings, it should be understood that like reference numbers refer to like features, structures and elements.  
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS  
      Exemplary embodiments of the present invention will now be described in detail with reference the accompanying drawings.  
       FIG. 2  is a block diagram of an apparatus for printing an image without borders according to an embodiment of the present invention. The apparatus comprises an image division unit  210 , a division region selector  220 , an image expansion unit  230 , an expansion method selector  240 , and a printing unit  250 . The image expansion unit  230  comprises an expansion pixel searching unit  232 , a pixel value calculator  234 , and a memory unit  236 .  
      When an image is input to the image division unit  210 , the image division unit  210  divides the input image into at least two image regions based on the size of printing paper. Prior to the image being printed, the size of the printing paper may be selected via a user interface or be automatically determined by the apparatus. Also, the patterns and sizes of the image regions into which the input image is divided may have been predetermined or may be selected by a user using the division region selector  220  prior to the printing of the image.  
      The image expansion unit  230  calculates the expansion pixel values of the pixels in each of the divided image regions using an image expansion method corresponding to each of the divided image regions. The expansion of the image leads to the creation of expansion pixels with unknown values. Interpolation is preferably used to calculate the values of the expansion pixels. In this case, various methods for interpolation, such as repetitive interpolation, bi-linear interpolation, bi-cubic interpolation or other suitable interpolation methods, can be used. However, the present invention is not limited to the above described methods of interpolation, and those of skill in the art will appreciate that other image expansion methods may be used.  
      In repetitive interpolation, the values of the pixels closest to the expansion pixels are determined as the values of expansion pixels. Thus, repetitive interpolation allows the values of expansion pixels to be quickly calculated. However, repetitive interpolation may cause the printed input image to be different from the input image.  
      In bi-linear interpolation, the values of the expansion pixels are calculated by giving weights to the values of four pixels adjacent to each of the expansion pixels, multiplying the values of the four pixels by the given weights, respectively, and adding the results of multiplication together. The value of a pixel with the coordinate (x, y) positioned between two pixels with coordinates (x 0 , y 0 ) and (x 1 , y 1 ) on a one-dimensional plane, is computed using Equation (1). The value of the pixel positioned on a two-dimensional plane is computed by performing Equation (1) twice, once in each dimension. 
 
 y=y   0 +( y   1   −y   0 )/( x   1   −x   0 )×( x   1   −x   0 )  (1) 
 
      In bi-cubic interpolation, the values of the expansion pixels are more precisely computed using a cubic function and the values of sixteen pixels around each of the expansion pixels. Equation (2) is used to compute the value of an expansion pixel on a one-dimensional plane. That is, the value of the new pixel is obtained using the values of four pixels with coordinates (x 0 , y 0 ), (x 1 , y 1 ), (x 2 , y 2 ), and (x 3 , y 3 ) around the new pixel. A matrix representation of Equation (2) may be expressed by Equation (3). The coefficient a of the cubic equation is obtained by multiplying the reverse matrix of the matrix [X] in Equation (3) by the matrix [Y] as expressed in Equation (4). 
 
 y   0   =a   0   +a   1   x   0   +a   2   x   0   +a   3   x   0   3 , 
 
 y   1   =a   0   +a   1   x   1   +a   2   x   1   2   +a   3   x   1   3 , 
 
 y   2   =+a   0   +a   1   x   2   +a   2   x   2   2   +a   3   x   2   3 , 
 
 y   3   =a   0   +a   1   x   3   +a   2   x   3   2   +a   3   x   3   3   (2) 
 
[ X] [a]=[Y]   ( 3 ) 
 
[ a]=inv ([ X ])[ Y]   (4) 
 
      That is, in bi-cubic interpolation, the value of the new pixel on the one-dimensional plane is obtained by computing the values of the four pixels around the new pixel using Equation (2), and then, the value of the new pixel on the two-dimensional plane is obtained using the four pixel values.  
      The expansion pixel searching unit  232  of the image expansion unit  230  searches for the expansion pixels from expanded image regions obtained by expanding the image regions divided by the image division unit  220 . The pixel value calculator  234  calculates the values of the searched expansion pixels according to the image expansion methods corresponding to the divided image regions. For instance, the expansion pixel searching unit  232  searches for expansion pixels at the center of the expanded image and expansion pixels at the edge thereof. The pixel value calculator  234  computes the values of the expansion pixels at the center using either a bi-linear interpolation or bi-cubic interpolation method, and the values of the expansion pixels at the edge of the image are computed using the repetitive interpolation method. The memory unit  236  stores a plurality of image expansion methods.  
      The image expansion methods may have been predetermined according to the patterns of the image regions into which the input image was divided, or selected from the plurality of image expansion methods stored in the memory unit  236  by a user using the expansion method selector  240  whenever an image is to be printed. The input image is expanded using the image expansion methods corresponding to the divided image regions. The expanded image data is processed, such as color matching and halftoning, and the resulting processed image is printed by the printing unit  250 .  
       FIGS. 3A and 3B  illustrate the patterns and sizes of image regions into which an input image is divided according to an embodiment of the present invention. In more detail,  FIG. 3A  illustrates the patterns of a low-definition image region  310   a  and a high-definition image region  320   a  into which the input image is divided.  FIG. 3B  illustrates the patterns of a low-definition image region  330   b , a middle-definition image region  320   b , and a high-definition image region  310   b.    
      In other words, referring to  FIG. 3A , a center portion of the image is the high-definition image region  320   a  and an edge portion thereof is the low-definition image region  310   a . Referring to  FIG. 3B , a center portion of the image is the high-definition image region  310   b , an edge portion thereof is the low-definition image region  330   b , a portion between the center portion and the edge portion is the middle-definition image region  320   b.    
      According to embodiments of the present invention, a user can determine the desired patterns and sizes of the image regions into which an input image is divided, using the division region selector  220 . The patterns and sizes of image regions shown are intended to be exemplary and are not limited to those shown in  FIGS. 3A and 3B .  
       FIG. 4  is a flowchart illustrating a method of printing an image according to an embodiment of the present invention. Referring to  FIG. 4 , it is determined whether a borderless image printing mode is selected via a predetermined user interface (operation  410 ). When it is determined in operation  410  that the borderless image printing mode is selected, the image is divided into at least two image regions (operation  420 ). Next, expansion pixels are searched for from the divided image regions (operation  430 ). For printing an image without borders, the image must be expanded to be slightly larger than the size of the printing paper, and image expansion results in expansion pixels to be present in the divided image regions. Next, the values of the expansion pixels are computed according to the image expansion methods corresponding to the divided image regions, respectively, thus obtaining an expanded image (operation  440 ). As described above, repetitive interpolation, bi-bipolar interpolation, and bi-cubic interpolation are examples of interpolation methods used to compute the values of the expansion pixels. However, the types of interpolation applied to the present invention are not limited to the above image expansion methods. The expanded image obtained in operation  440  is processed by image data processing such as color matching and halftoning, and then, the resulting image data is printed (operation  450 ).  
      If the borderless printing mode is not selected via the predetermined user interface, the image is printed using a conventional image printing method.  
       FIG. 5  is a flowchart illustrating a method of printing an image according to another embodiment of the present invention. Referring to  FIG. 5 , it is determined whether a borderless image printing mode is selected via a predetermined user interface (operation  510 ). When it is determined in operation  510  that the borderless image printing mode is selected, the pattern and sizes into which the image is to be divided into image regions are selected (operation  520 ). The patterns of the image regions may be selected as either of a high-definition image region and a low-definition image region, or a high-definition image region, a middle-definition image region, and a low-definition image region, using the division region selector  220  of  FIG. 2 . However, embodiments of the present invention are not limited to the above patterns, that is, the image can be divided into a plurality of image regions according to various patterns. The sizes of image regions into which the image is to be divided are selected using the division region selector  220  of  FIG. 2 . According to embodiments of the present invention, the sizes of image regions also are not limited. Thereafter, the image is divided into the image regions of the selected sizes according to the selected pattern determined in operation  520  (operation  530 ).  
      After operation  530 , image expansion methods that will be used to expand the divided image regions, respectively, are selected from a plurality of image expansion methods (operation  540 ). For image expansion, various types of interpolation may be used according to embodiments of the present invention. Expansion pixels are searched for from the divided image regions (operation  550 ). An expanded image is obtained by computing the values of the searched expansion pixels using the image expansion methods matching the respective image regions, selected in operation  540  (operation  560 ). The expanded image is processed by image data processing such as color matching and halftoning, and the resulting processed image data is printed (operation  570 ).  
      If the borderless printing mode is not selected via the predetermined user interface, the image is printed using a conventional image printing method. Operations  510 ,  530 ,  550 , and  560  generally correspond to operations  410 ,  420 ,  430 , and  440  of  FIG. 4 , respectively.  
       FIGS. 6A and 6B  are detailed flowcharts illustrating a method of enlarging an image according to the patterns of image regions into which the image is divided, as performed in operation  440  of the method of  FIG. 4  or operation  560  of the method of  FIG. 5 , according to embodiments of the present invention. More specifically,  FIGS. 6A and 6B  illustrate methods of enlarging a high-definition image region and a low-definition image region into which an image is divided, respectively, according to an embodiment of the present invention.  FIG. 6C  illustrates a method of enlarging a high-definition image region, a middle-definition image region, and a low-definition image region into which an image is divided according to an embodiment of the present invention.  
      In the method of  FIG. 6A , in operation  610   a , it is determined whether expansion pixels are present in the high-definition image region using the expansion pixel searching unit  232  of  FIG. 2 . If the high-definition image region contains the expansion pixels, the values of the expansion pixels are computed using bi-cubic interpolation or bi-linear interpolation (operation  620   a ). If the high-definition image region does not contains the expansion pixels, the values of the expansion pixels are preferably computed using the repetitive interpolation method (operation  630   a ).  
      In the method of  FIG. 6B , in operation  610   b , it is determined whether expansion pixels are present in the high-definition image region using the expansion pixel searching unit  232 . If the high-definition image region contains the expansion pixels, the values of the expansion pixels are computed using bi-cubic interpolation (operation  620   b ). If the high-definition image region does not contain the expansion pixels, the values of the expansion pixels are preferably computed using the bi-linear interpolation method (operation  630   b ).  
      In the method of  FIG. 6C , in operation  610   c , it is determined whether expansion pixels are present in the high-definition image region using the expansion pixel searching unit  232 . If the high-definition image region contains the expansion pixels, the values of the expansion pixels are preferably computed using the bi-cubic interpolation method (operation  620   c ). If the high-definition image region does not contain the expansion pixels, and it is determined that the expansion pixels are contained in the middle-definition image region (operation  630   c ), the values of the expansion pixels are preferably computed using the bi-linear interpolation method (operation  640   c ). However, when the expansion pixels are not contained in the middle-definition image region or the high-definition image region, the values of the expansion pixels are preferably computed using the repetitive interpolation method (operation  650   c ).  
       FIG. 7  is a block diagram of an apparatus for printing an image without borders according to another embodiment of the present invention. The apparatus comprises a print mode selecting unit  710 , an image expansion unit  720 , and a printing unit  730 . The print mode selecting unit  710  comprises a print quality selector  712  and a printing paper selector  714 . A user command that instructs a print mode to be selected according to the print quality and the printing paper is input via the print quality selector  712  and the printing paper selector  714 . The image expansion unit  720  determines the print mode selected by the print mode selecting unit  710  and computes the values of the expansion pixels using an image expansion method corresponding to the determined print mode. The image expansion method may have been predetermined by a manufacturer of the apparatus or a predetermined image expansion method can be selected according to a predetermined print mode by a user. The values of expansion pixels can be computed using various types of interpolation methods, such as repetitive interpolation, bi-linear interpolation, and bi-cubic interpolation methods, as described above.  
      The print mode determination unit  722  of the print expansion unit  720  determines the print mode according to the print quality and printing paper selected by the print quality selector  712  and the printing paper selector  714 . A calculator  724  of the print expansion unit  720  calculates the values of the expansion pixels obtained by image expansion, using the image expansion method determined by the print mode, and obtains an expanded image using the pixel values. The printing unit  730  processes the expanded image using color matching or halftoning and prints the resulting processed image data.  
       FIG. 8  is a block diagram of the print mode selecting unit  710  of the apparatus of  FIG. 7  according to an embodiment of the present invention. The print mode selecting unit  710  comprises a print quality selector  712  and a printing paper selector  714  to which a user command is input. A user may input a user command that selects the quality of image to which an image is to be enlarged, via the print quality selector  712 . For instance, the quality of image may be determined as high quality, standard quality, general quality, or high-speed draft quality. Also, the user may input a user command that selects the type of paper on which the image is to be printed, via the printing paper selector  714 . For instance, the type of paper may be determined as high-quality printing paper, general printing paper, or general paper. The user will also have the option to confirm or cancel the quality and printing paper selections.  
       FIG. 9  is a block diagram of the print mode selecting unit  710  of the apparatus of  FIG. 7  according to another embodiment of the present invention. The print mode selecting unit  710  comprises a print quality selector  712  and a printing paper selector  714 , and further comprises an image expansion method selector  916 . A user may input a user command that selects a print expansion method corresponding to the desired print quality and paper quality selected, via the image expansion method selector  916 . For instance, the image expansion method may be bi-cubic interpolation, bi-linear interpolation, repetitive interpolation or other suitable method. Again, the user has the option to confirm or cancel the selections.  
       FIG. 10  is a flowchart illustrating a method of printing an image without borders according to an embodiment of the present invention. Referring to  FIG. 10 , an image expansion method may have been predetermined according to the selected print mode, or be selected from a plurality of image expansion methods by a user or according to the characteristics of image to be printed via the image expansion method selector  916  (operation  1010 ). A print mode to which an image is to be enlarged is determined according to a user command input via the print quality selector  712  of  FIG. 7  (operation  1020 ). When a predetermined print mode is selected in operation  1020 , the image is enlarged according to an image expansion method corresponding to the selected print mode ( 1030 ). Next, the expanded image is processed using image data processing such as color matching and halftoning, and the resulting processed image data is printed by the printing unit  730  ( 1040 ).  
       FIG. 11  is a flowchart illustrating a method of printing an image without borders according to another embodiment of the present invention. Referring to  FIG. 11 , an image expansion method may have been predetermined according to the print mode and a printing paper mode or be selected from a plurality of image expansion methods by a user or according to the characteristics of the image to be printed via the image expansion method selector  916  (operation  1110 ). The print mode to which an image is to be enlarged is determined according to a user command input via the print quality selector  712  of  FIG. 7  (operation  1120 ). Also, the type of paper on which an image is to be printed is determined according to a user command input via the printing paper selector  714  ( 1130 ). The image is expanded using the image expansion method determined by the print mode and printing paper mode selected in operations  1120  and  1130  (operation  1140 ). Thereafter, the expanded image is processed by image data processing such as color matching and halftoning and the resulting processed image data is printed by the printing unit  730  ( 1150 ).  
       FIGS. 12A and 12B  are flowcharts illustrating methods of enlarging an image according to a print mode determined by print quality and the type of printing paper, included in the exemplary methods of  FIGS. 10 and 11 , respectively. In the exemplary methods of  FIGS. 12A and 12B , a print mode is determined and an image expansion method is determined according to the determined print mode; or a print mode is determined, a printing paper mode is determined according to the determined print mode, and then, an image expansion method is determined. Alternatively, a printing paper mode may be determined and an image expansion method may be determined according to the determined printing paper mode, or a printing paper mode may be determined, a print mode is determined according to the printing paper mode, and then, an image expansion method may be determined.  
      Referring to  FIG. 12A , it is determined whether a print mode selected according to the print quality is a high-quality mode (operation  1210   a ). When the selected print mode is the high-quality mode, an image that is to be printed is preferably enlarged using the bi-linear interpolation or bi-cubic interpolation methods ( 1220   a ). If the print mode is a mode other than the high-quality mode, the image is preferably enlarged using the repetitive interpolation method (operation  1230   a ).  
      Referring to  FIG. 12B , it is determined whether a print mode selected according to print quality is a high-quality mode (operation  1210   b ). When it is determined in operation  1210   b  that the selected print mode is the high-quality mode, it is determined whether a print mode is selected according to whether the type of printing paper is a high-quality printing paper mode (operation  1230   b ). When it is determined in operation  1230   b  that the print mode is the high-quality printing paper mode, the image is preferably enlarged using the bi-cubic interpolation method (operation  1240   b ). However, when the print mode is a mode other than the high-quality printing paper mode, the image is enlarged using the bi-linear interpolation method (operation  1250   b ). When it is determined in operation  1210   b  that the selected print mode is a mode other than the high-quality mode, the image is preferably enlarged using the repetitive interpolation method (operation  1220   b ).  
      The present invention can be embodied as a computer program that is executed using a computer, and be recorded on a computer readable medium and executed by a general digital computer. The computer readable medium may be a magnetic storage medium, such as a read-only memory (ROM), a floppy disk, or a hard disk; an optical data storage medium, such as a compact disc (CD)-ROM or a digital versatile disc (DVD); or a carrier wave that transmits data via the Internet.  
      In a method and apparatus for printing an image without borders according to embodiments of the present invention, an image to be printed is divided into a high-definition image region and a low-definition image region, these regions are enlarged and printed using different image expansion methods, thereby minimizing the reduction in the quality of the image to be printed and the delay in processing the image to be printed.  
      In the method and apparatus according to embodiments of the present invention, an image to be printed is divided into a high-definition image region and a low-definition image region as users&#39; desire or according to the characteristics of the image, and these regions are expanded and printed according to different image expansion methods.  
      Also, the method and apparatus according to embodiments of the present invention allow a user to select a print mode according to the print quality and printing paper in consideration of the characteristics of the image or as the user desires, and enlarge and print the image using an image expansion method determined according to the print mode. Accordingly, it is possible to quickly and effectively print the image without borders while minimizing the reduction in the quality of image to be printed.  
      While this invention has been particularly shown and described with reference to exemplary embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.