Abstract:
A method of enlarging an image by interpolation means and a related digital camera are disclosed. The method comprises: dividing an original image into a plurality of divided sections; defining a first divided section selected from the plurality of divided sections; defining a second divided section from the divided sections adjacent thereto and continuing until defining a final divided section; enlarging the first divided section by a first specific multiplier and zooming out by a second specific multiplier by using the interpolation means to form a first processed section, and continuing until a final processed section is formed. The first processed section to the final processed section thereby form an enlarged image.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The present invention relates to a method of enlarging an image and a related digital camera, and, more particularly, to a method of enlarging an image by an interpolation means and a related digital camera.  
         [0003]     2. Description of the Related Art  
         [0004]     One of the most important elements in digital cameras is a charge coupled device (CCD). The digital camera utilizes the CCD to convert impinging light signals into electronic signals, and records these signals in a built-in memory (such as a 32M or a 16M SDRAM) within the digital camera to form images.  
         [0005]     The most basic unit of an image is the pixel; pixels are the points that compose the image. Therefore, images with more pixels are of better quality. For a 1,600×1,200 pixel image file, there are 1,920,000 pixels, meaning that the image is composed of 1,920,000 points. The maximum pixel resolution of the digital camera is determined by the number of the CCDs in the digital camera.  
         [0006]     However, the CCD is an expensive element, and so the number of the CCD is usually limited in the digital camera. Therefore, some manufacturers utilize “interpolation means” to increase the number of pixels. The original image data with fewer pixels is operated upon the interpolation means to form an image data having more pixels.  
         [0007]     Traditionally, the interpolation means is limited by the size of the buffer, because the buffer can only hold images of limited size. The general solution is to store the reduced image in the buffer and then store the enlarged image back into the memory in the digital camera. However, the enlarged image may cause saw-toothed edges, which degrade the image quality.  
       SUMMARY OF THE INVENTION  
       [0008]     A digital camera of the present invention enlarges an original captured image and stores the original captured image in a memory of the digital camera. The method of enlarging an original image of the present invention thus can provide the enlarged images with the same quality and require less buffer capacity to improve the functioning of the digital camera.  
         [0009]     The digital camera of the present invention comprises a digital signal processor (DSP) and a memory. The memory stores an application program interface (API), and comprises a buffer and an image data storage area. An original image is capable of being stored in the image data storage area, and the application program interface is usable for calling the digital signal processor to zoom in on the original image.  
         [0010]     The digital signal processor is used to perform the invention method of enlarging the original image, which comprises:  
         [0011]     (a) dividing an original image into a plurality of divided sections;  
         [0012]     (b) defining a first divided section selected from one of corner divided sections of the plurality of divided sections;  
         [0013]     (c) defining sequential divided sections from the divided sections adjacent to the first divided section thereto and continuing until defining a final divided section;  
         [0014]     (d) enlarging the first divided section by a first specific multiplier and reducing by a second specific multiplier by using the interpolation means; wherein the first specific multiplier is larger than the second specific multiplier so the first divided section is zoomed in as a first processed section by using the interpolation means; and  
         [0015]     (e) enlarging the second divided section by the first specific multiplier and reducing by the second specific multiplier by using the interpolation means to form a second processed section, and repeating the process until a final processed section is formed, the first processed section to the final processed section thereby forming an enlarged image.  
         [0016]     Generally, the enlargement or reduction multipliers of the digital signal processor are constants, which indicates that the enlargement multiplier for the original image is a fixed multiplier (such as 1.26 times or 1.28 times). Therefore, in the preferred embodiment of the present invention, the first specific multiplier is 2, and the second specific multiplier is 1.25×1.25. For example, the original image may be about a 3M pixel image, and the enlarged image might be about a 5M pixel image.  
         [0017]     In the preferred embodiment of the present invention, each divided section has at least one overlapping area. After enlargement and reduction of the overlapped areas, visible dividing lines are not generated between the processed sections.  
         [0018]     Furthermore, in the method, step (c) further comprises:  
         [0019]     separately overlapping at least one area of the second divided section and the third divided section with the first divided section; and  
         [0020]     separately overlapping at least one area of the divided sections adjacent the second divided section with the second divided section, and repeating the process with every divided section until the final divided section is reached.  
         [0021]     The digital signal processor can be used for controlling the partition sizes of the divided sections and for obtaining very minor differences. Therefore, this embodiment can make overlapping areas having widths of only 2 to 4 pixels. By enlarging and reducing the divided sections to enhance the overlapping areas, visible division lines between every two processed sections are avoided, and so the entire enlarged image appears clearer. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]      FIG. 1  is a functional block drawing of a digital camera according to the present invention.  
         [0023]      FIG. 2  is a flow chart of a method of the present invention.  
         [0024]      FIG. 3A ˜ FIG. 3F  are schematic drawings of enlarging on an original image according to the present invention.  
         [0025]      FIG. 4  shows another embodiment of the present invention, which shows more divided sections.  
         [0026]      FIG. 5  is a flow chart of a method of enlarging an original image according to the present invention.  
         [0027]      FIG. 6A ˜ FIG. 6C  show a method of enlarging an original image according to another embodiment of the present invention, which shows that divided sections all have at least one overlapping area. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0028]     Please refer to  FIG. 1 .  FIG. 1  is a functional block drawing of a digital camera according to the present invention. A digital camera  1  of the present invention comprises a digital signal processor (DSP)  3  and a memory  5 . The digital camera  1  utilizes interpolation means to zoom in on an original image  10  to form an enlarged image  20  shown as dotted lines. The memory  5  comprises a buffer and an image data storage area D, and the original image  10  and the enlarged image  20  are all stored in the image data storage area D.  
         [0029]     The original image  10 , which may be captured by the digital camera  1 , is stored in the memory  5  of the digital camera  1 . The memory  5  can be implemented by a SDRAM in the digital camera  1 . Additionally, the original image  10  in the present invention is not limited to only images captured by the digital camera  1 , but may also be an imported image (for example, downloaded from a computer) stored in the memory  5  of the digital camera  1 .  
         [0030]     The digital signal processor  3  of the digital camera  1  is used for converting electronic signals generated by the CCD (not shown) in the digital camera  1  to a digital image and performing image processing. The memory  5  has an application program interface (API)  52 , which can be used for calling the digital signal processor  3  to zoom in on the original image  10 .  
         [0031]     Please refer to  FIG. 2 . In step S 21 , the original image  10  is divided into a plurality of divided sections. Please refer to  FIG. 3A ; when a user obtains the original image  10 , and if the user wants to zoom in on the original image  10  into an enlarged image  20 , the method of the present invention may be performed. As shown in  FIG. 3B , the original image  10  is divided into divided sections B 1 ˜B 4 .  
         [0032]     In  FIG. 3A ˜FIG  3 F, the original image  10  is divided into four divided sections B 1 ˜B 4 ; however, it should be understood that the number of divided sections can vary; for example, as shown in  FIG. 4 , the original image  10  can be divided into nine divided sections b 1 ˜b 9 . The number of divided sections B 1 ˜B 4  or b 1 ˜b 9  is depends on the size of the buffer B (as shown in  FIG. 1 ). In other words, if the buffer B has a relatively large size, there may be fewer divided sections (such as B 1 ˜B 4 ), and each divided section B 1 ˜B 4  may have a relatively large size; on the other hand, the buffer B is smaller sized, there may be more divided sections (such as b 1 ˜b 9 ) and each divided section b 1 ˜b 9  may have a smaller size. In the following description, the divided sections B 1 ˜B 4  are used as examples.  
         [0033]     Please refer again to  FIG. 2 . In step S 22 , one divided section at one corner of the divided sections B 1 ˜B 4  is defined as a first divided section. Please refer to  FIG. 3B . In this embodiment, the divided section B 1  is defined as the first divided section. The defined first divided section is selected from one of the divided sections B 1 ˜B 4  or b 1 ˜b 9 , which is positioned at a corner, such as any one of divided sections B 1 , B 2 , B 3 , or B 4 , or any one of divided sections b 1 , b 4 , b 6 , or b 9 .  
         [0034]     Next, in step S 23 , the second divided section, the third divided section . . . and the final divided section are all defined sequentially. Please refer to  FIG. 3B ; in this embodiment, the divided sections B 2  and B 3  adjacent to the first divided section B 1  are defined as the second divided section B 2  and the third divided section B 3 . However, choosing the second divided section as B 2  and the third divided section as B 3  is not the only option; the second divided section may be B 3 , and the third divided section may be B 2 . For convenience of description, the second divided section as B 2  and the third divided section as B 3  is used as an example. Sequentially, the fourth divided section B 4  to the final divided section are defined. In this embodiment, the fourth divided section B 4  is the final divided section.  
         [0035]     Alternatively, with reference to  FIG. 4 , the divided sections b 2  and b 3  adjacent to the first divided section b 1  may be defined as the second divided section b 2  and the third divided section b 3 . Next, the fourth divided section b 4  and the fifth divided section b 5  adjacent to the second divided section b 2  are defined, and the sixth divided section b 6  adjacent to the third divided section b 3  is defined. Next, the divided section adjacent to the fourth divided section b 4  is defined as the seventh divided section b 7 , and the divided section adjacent to the fifth divided section b 5  is defined as the eighth divided section b 8 . Finally, the divided section adjacent to both the seventh divided section b 7  and the eighth divided section b 8  is defined as the ninth divided section b 9 . The second divided section b 2  and the third divided section b 3  are not necessarily in sequence; neither are the fourth divided section b 4 , the fifth divided section b 5 , and the sixth divided section b 6  in sequence; and the seventh divided section b 7  and the eighth divided section b 8  are not necessarily in sequence either.  
         [0036]     With reference to  FIG. 2 , in step S 24 , the first divided section B 1  is stored in the buffer B, and the interpolation means is utilized to enlarge the first divided section B 1  by a first specific multiplier and reducing the enlarged first divided section B 1  with a second specific multiplier. The first specific multiple is larger than the second specific multiplier; preferably, the first specific multiplier is 2, and the second specific multiple is 1.25×1.25. As a result, the first divided section B 1  is enlarged as a first processed section B 1 ′ by the interpolation means, and the first processed section B 1 ′ is stored back into the image data storage area D. With reference to  FIG. 3C , the first divided section B 1  is stored in the buffer B. The interpolation means is used for enlarging the first divided section B 1  by the first specific multiplier (such as 2) and reducing by the second specific multiplier (such as 1.25×1.25) so that the first divided section B 1  is enlarged (such as by 1.28 times) to form the first processed section B 1 ′. The first processed section B 1 ′ is stored back into the image data storage area D.  
         [0037]     With reference to  FIG. 2 , in step S 25 , the second divided section B 2  is stored in the buffer B, and the interpolation means is utilized to enlarge the second divided section B 2  by the first specific multiplier (such as 2) and to reduce the second divided section B 2  by a second specific multiplier (such as 1.25×1.25). The second divided section B 2  is therefore enlarged as a second processed section B 2 ′ by the interpolation means, and the second processed section B 2 ′ is stored back into the image data storage area D. Accordingly, eventually the final divided section B 4  is enlarged by the first specific multiplier (such as 2) and reduced by the second specific multiple (such as 1.25×1.25) by the interpolation means to form the last processed section B 4 ′. Please also refer to  FIG. 3D ˜ FIG. 3F . As shown in  FIG. 3D , the second divided section B 2  stored in the buffer B utilizes the interpolation means for enlargement by the first specific multiplier (such as 2) and reduction by the second specific multiplier (such as 1.25×1.25) to form the second processed section B 2 ′, and the second processed section B 2 ′ is stored back into the image data storage area D. Next, as shown in  FIG. 3E , the third divided section B 3  stored in the buffer B utilizes the interpolation means for enlargement by the first specific multiplier (such as 2) and for reduction by the second specific multiplier (such as 1.25×1.25) to form the third processed section B 3 ′, and the third processed section B 3 ′ is stored back into the image data storage area D. Finally, as shown in  FIG. 3F , the fourth divided section B 4  stored in the buffer B utilizes the interpolation means for enlargement by the first specific multiplier (such as 2) and reduction by the second specific multiplier (such as 1.25&#39;1.25) to form the fourth processed section B 4 ′ (which is also the final processed section in this embodiment), and the fourth processed section B 4 ′ is stored back into the image data storage area D.  
         [0038]     With reference to  FIG. 2 , in step S 26 , all processed sections from B 1 ′ to B 4 ′ form the enlarged image  20  in the image data storage area D. As shown in  FIG. 3F , the first processed section B 1 ′ to the final processed section B 4 ′ form the enlarged image  20 , which is formed of enlarging the original image  10 .  
         [0039]     Generally, the enlargement or reduction multipliers of the digital signal processor  3  are constants, which indicates that the enlargement multiplier for the original image  10  is a fixed multiplier (such as 1.26 times or 1.28 times). Therefore, in the preferred embodiment of the present invention, the first specific multiplier is 2, and the second specific multiplier is 1.25×1.25. For example, the original image  10  may be a 3M pixel image, and the enlarged image  20  might be a 5M pixel image.  
         [0040]     When the digital signal processor  3  processes the image, dividing lines L between every two divided sections B 1 ˜B 4  (as shown in  FIG. 3F ) may become noticeable. Therefore, in the preferred embodiment of the present invention, each divided section B 1 ˜B 4  has at least one overlapping area. After enlargement and reduction of the overlapped areas, the dividing lines L are not generated between the processed sections B 1 ′˜B 4 ′.  
         [0041]     Please refer to  FIG. 5 . In one preferred embodiment, after step S 22  of defining the first divided section B 1 , step S 231  is performed to overlap at least one area of each divided section B 1 ˜B 4 . When defining the divided sections B 1 ˜B 4 , the overlapping areas are also defined. Therefore, step S 231  may further comprise steps S 232  and S 233 . With reference to  FIG. 6A , the first divided section B 1  is defined first, and the overlapping areas C 1 ˜C 5  are separately defined between every two divided sections among the divided sections B 1 ˜B 4 .  
         [0042]     Please refer to both  FIG. 5  and  FIG. 6B . In step S 232 , the larger second divided section B 2  is extracted, so the second divided section B 2  and the first divided section B 1  have the overlapping areas C 1 , C 3  between them; the larger third divided section B 3  is extracted, and so the third divided section B 3  and the first divided section B 1  have the overlapping areas C 2 , C 3 .  
         [0043]     Please refer to both  FIG. 5  and  FIG. 6B . In step S 233 , the larger fourth divided section B 4  (also the final divided section in this embodiment) is extracted, and so the fourth divided section B 4  and the second divided section B 2  have the overlapping areas C 4 , C 3  between them, and the fourth divided section B 4  and the third divided section B 3  share the overlapped areas C 5 , C 3 .  
         [0044]     The digital signal processor  3  can be used for controlling the partition sizes of the divided sections B 1 ˜B 4  and for obtaining very minor differences. Therefore, this embodiment can make the overlapping areas C 1 ˜C 5  have widths of only 2 to 4 pixels. Steps S 24 , S 25  and S 26  are performed after step S 232 , as provided in the above-mentioned description.  
         [0045]     By enlarging and reducing to enhance the overlapping areas C 1 ˜C 5 , visible division lines L among the processed sections B 1 ′˜B 4 ′ are avoided, and so the entire enlarged image  20  appears more clear, as shown in  FIG. 6C .  
         [0046]     According to the method of the present invention, the enlarged image retains its picture quality, and every divided section (such as B 1 ˜B 4  or b 1 ˜b 9 ) is much smaller than the original image  10 , which requires less memory capacity in the buffer, and further improves the entire processing performance of the digital camera.  
         [0047]     Although the present invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.