Patent Publication Number: US-11025840-B2

Title: Image sensor and method for extracting edge of image based on amplitudes of signals output from pixels

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This U.S. non-provisional patent application claims priority under 35 U.S.C. § 119 of Korean Patent Application No. 10-2018-0031594, filed on Mar. 19, 2018, the entire contents of which are hereby incorporated by reference. 
     BACKGROUND 
     The present disclosure herein relates to an image sensor and method, and more particularly, to an image sensor and method for extracting an edge of an image based on amplitudes of signals output from pixels. 
     With recent advances in technology, image sensors may be used for pattern recognition techniques used in autonomous navigation, face recognition, security cameras, factory automation, medical diagnostics, and the like. In addition, the image sensor may be used to recognize not only a pattern but also various subjects such as a user&#39;s input, a gesture, a face, a thing, and the like. 
     The image sensor may include a Charge Coupled Device (CCD) and a CMOS Image Sensor (CIS). For low power and high integration, CIS may be mainly used rather than CCD. The image sensor may receive optical signals from the subject and output electrical signals. In order to recognize the subject, the edge noise of the image may be removed or the edge of the image may be emphasized. Therefore, there is a need for an image sensor capable of extracting an edge of an image using electrical signals. 
     SUMMARY 
     The present disclosure is to provide an image sensor and method for extracting an edge of an image based on amplitudes of signals outputted from pixels. 
     An embodiment of the inventive concept provides an image sensor including: a pixel array including pixels arranged along a first direction and a second direction, and partitioned into blocks; a converter configured to convert image signals outputted from the pixels into digital signals based on an image; and an image signal processor configured to add amplitudes of the digital signals belonging to each of the blocks to determine edge blocks among the blocks, compare the amplitudes of the digital signals to determine directions in which direction lines of the edge blocks are directed, and connect the direction lines to extract an edge of the image. 
     In an embodiment of the inventive concept, an operation method of an image sensor with a pixel array including pixels arranged along a first direction and a second direction, and partitioned into blocks, a converter configured to convert image signals outputted from the pixel array into digital signals based on an image, and a memory includes: storing, by an image signal processor, addresses of blocks partitioning the pixel array in the memory; determining, by the image signal processor, edge blocks among the blocks by adding amplitudes of the digital signals; comparing, by the image signal processor, the amplitudes of the digital signals to determine directions in which the direction lines of the edge blocks are directed; and connecting, by the image signal processor, the direction lines to extract an edge of the image. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
       The accompanying drawings are included to provide a further understanding of the inventive concept, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of the inventive concept and, together with the description, serve to explain principles of the inventive concept. In the drawings: 
         FIG. 1  is a block diagram exemplarily illustrating an image sensor according to an embodiment of the inventive concept; 
         FIG. 2  shows the pixel array of  FIG. 1  in more detail; 
         FIG. 3  is a flowchart illustrating an exemplary method of extracting an edge of an image according to an embodiment of the inventive concept; 
         FIG. 4  is a flowchart illustrating an example of detailed operations of operation S 130  of  FIG. 3 ; 
         FIG. 5  illustrates an example in which an image signal processor determines blocks that partition a pixel array according to operation S 130  of  FIG. 3 , including operations S 131  to S 135  of  FIG. 4 ; 
         FIGS. 6 to 8  illustrate an example in which an edge of an image is determined according to an embodiment of the inventive concept; 
         FIG. 9  illustrates an example in which the pixel arrays of  FIG. 1  are partitioned into blocks that are overlapped with each other according to an embodiment of the inventive concept; 
         FIG. 10  is a flowchart illustrating an example of detailed operations of operation S 140  of  FIG. 3 ; 
         FIGS. 11 and 12  exemplarily illustrate edge blocks having the same amplitudes of the first direction signals and the second direction signals; 
         FIG. 13  exemplarily shows edge blocks having the same amplitudes of the first direction signals; 
         FIG. 14  exemplarily shows edge blocks having the same amplitudes of the second direction signals; 
         FIG. 15  is a flowchart illustrating an example of detailed operations of operation S 140  of  FIG. 3 ; 
         FIG. 16  exemplarily shows an edge block in which the sum of the amplitudes of the third direction signals is larger than the sum of the amplitudes of the fourth direction signals; 
         FIG. 17  exemplarily shows an edge block in which the sum of the amplitudes of the fourth direction signals is larger than the sum of the amplitudes of the third direction signals; 
         FIG. 18  exemplarily shows an edge block in which the sum of the amplitudes of the direction signals of the upper pixels is greater than the sum of the amplitudes of the direction signals of the lower pixels and the amplitude of the direction signal of the left pixel is larger than the amplitude of the direction signal of the right pixel; 
         FIG. 19  exemplarily shows an edge block in which the sum of the amplitudes of the direction signals of the upper pixels is greater than the sum of the amplitudes of the direction signals of the lower pixels and the amplitude of the direction signal of the right pixel is larger than the amplitude of the direction signal of the left pixel; 
         FIG. 20  exemplarily shows an edge block in which the sum of the amplitudes of the direction signals of the lower pixels is greater than the sum of the amplitudes of the direction signals of the upper pixels and the amplitude of the direction signal of the left pixel is larger than the amplitude of the direction signal of the right pixel; 
         FIG. 21  exemplarily shows an edge block in which the sum of the amplitudes of the direction signals of the lower pixels is greater than the sum of the amplitudes of the direction signals of the upper pixels and the amplitude of the direction signal of the right pixel is larger than the amplitude of the direction signal of the left pixel; 
         FIGS. 22 and 23  illustrate an example in which an edge of an image is extracted according to an embodiment of the inventive concept; 
         FIG. 24  exemplarily illustrates a process of hierarchically extracting edges of an image according to another embodiment of the inventive concept; 
         FIGS. 25 and 26  illustrate a process of extracting a motion of an image according to another embodiment of the inventive concept; 
         FIG. 27  is a block diagram exemplarily illustrating an image sensor according to another embodiment of the inventive concept; and 
         FIG. 28  is a block diagram exemplarily illustrating an image sensor according to another embodiment of the inventive concept. 
     
    
    
     DETAILED DESCRIPTION 
     In the following, embodiments of the inventive concept will be described in detail so that those skilled in the art easily carry out the inventive concept. 
       FIG. 1  is a block diagram exemplarily illustrating an image sensor according to an embodiment of the inventive concept. The image sensor  100  may include a pixel array  110 , a row decoder  120 , a column decoder  130 , a converter  140 , an image signal processor  150 , and a timing controller  160 . 
     The pixel array  110  may include pixels (not shown) arranged along the X and Y axes. The pixels may be arranged in a two-dimensional matrix form. The pixels may receive optical signals from a subject (or object) through a lens (not shown) and a filter (not shown). The pixels may generate electrical image signals corresponding to the intensities of the optical signals. For example, each of the pixels may include a photodiode and at least one transistor. The physical size of one pixel may represent image resolution or may correspond to a minimum line width of the image. 
     The row decoder  120  may receive a row address, a timing signal, a control signal, etc. of the pixel array  110  from the timing controller  160 . The row decoder  120  may generate at least one driving signal for controlling the pixel array  110  in row units. For example, the row decoder  120  may sequentially drive the rows of the pixel array  110  under the control of the timing controller  160 . 
     The column decoder  130  may receive a timing signal, a control signal, and the like from the timing controller  160 . The column decoder  130  may detect the image signals generated in the pixels of the pixel array  110  connected to the row selected by the row decoder  120  through the columns. The column decoder  130  may provide the image signals of the pixel array  110  to the converter  140  based on the control of the timing controller  160 . 
     The converter  140  may receive the image signals from the column decoder  130  and convert the image signals to digital signals. For example, the converter  140  may be an analog-to-digital converter (ADC) and may include an amplifier, a comparator, a logic gate, a flip flop, and the like. The converter  140  may provide the converted digital signals to the image signal processor  150 . 
     An image signal processor (ISP)  150  may receive and process the digital signals. For example, the image signal processor  150  may be a digital signal processor (DSP) used for image processing in mobile devices such as digital cameras, smart phones, or the like or other electronic devices. The image signal processor  150  according to the embodiment of the inventive concept may extract the edge of the image as well as the original information of the image and may output the edge information of the image. For example, the image signal processor  150  may be referred to as an edge signal processor ESP. 
     The timing controller  160  may generate timing signals and control signals for the row decoder  120 , the column decoder  130 , the converter  140 , and the image signal processor  150 . The timing controller  160  may control an operation sequence, operation timings, and the like of the row decoder  120 , the column decoder  130 , the converter  140 , and the image signal processor  150 . 
     In an embodiment, all or a part of the pixel array  110 , the row decoder  120 , the column decoder  130 , the converter  140 , the image signal processor  150 , and the timing controller  160  may be integrated into one semiconductor chip (e.g., A system on chip (SoC), an application specific integrated circuit (ASIC), etc.), or a semiconductor package. Alternatively, each of the pixel array  110 , the row decoder  120 , the column decoder  130 , the converter  140 , the image signal processor  150 , and the timing controller  160  may be independently fabricated on a plurality of semiconductor chips. 
       FIG. 2  shows the pixel array of  FIG. 1  in more detail.  FIG. 2  will be described with reference to  FIG. 1 . Referring to  FIG. 2 , 2×2 pixels P 11 , P 12 , P 21 , and P 22  which are adjacent (contiguous) may be allocated to one block having a square shape. Here, a pixel may be referred to as a basic cell (BC) and a block may be referred to as a primitive cell (PC). And, the numbers in the pixels P 11 , P 12 , P 21 , and P 22  may indicate relative coordinates on the X and Y axes. 
     According to an embodiment of the inventive concept, the pixel array  110  may be partitioned into blocks. The size of the block may be m×n pixels. Herein, m may represent the number of pixels arranged along the X axis in one block and n may represent the number of pixels arranged along the Y axis in one block. m and n are integers of 2 or more and may be the same or different from each other. 
     The image signal processor  150  may extract an edge of an image in block units. The image signal processor  150  may preset the block size based on the user&#39;s request, image resolution, edge precision, edge extraction speed, and the like. The image signal processor  150  may configure the blocks through address selection of the pixel array  110  without additional hardware components associated with the pixel array  110 . The image signal processor  150  may extract the edges of the image based on the amplitudes (magnitudes) of the digital signals obtained by converting the image signals outputted from the 2×2 pixels P 11 , P 12 , P 21 , and P 22  of each of the blocks using the converter  140 . 
       FIG. 3  is a flowchart illustrating an exemplary method of extracting an edge of an image according to an embodiment of the inventive concept.  FIG. 3  will be described with reference to  FIGS. 1 and 2 . 
     In operation S 110 , the pixel array  110  may output image signals based on the image. The image signals may be analog signals, and the amplitudes of the image signals may correspond to the intensities of the optical signals incident from the subject. 
     In operation S 120 , the converter  140  may convert the image signals (analog signals) transmitted from the pixel array  110  into digital signals. For example, the converter  140  may quantize the amplitudes of the image signals to k bits. In this case, the amplitudes of the image signals may be quantized in 2 k  operations. Herein, k may be determined based on the speed, area, power consumption, accuracy, etc. of the converter  140 . As k is larger, the area and power consumption of the converter  140  may be larger, but the accuracy may also be increased. 
     In operation  130 , the image signal processor  150  may add digital signals belonging to each of the blocks of the pixel array  110 . For example, the image signal processor  150  may include an adder, a counter, etc. for addition operations. The image signal processor  150  may determine the edge blocks among the blocks by calculating the sum of the amplitudes of the digital signals belonging to each of the blocks. The edge of the image (or the edge of the subject on the pixel array  110 ) may be located in edge blocks. 
     In operation S 140 , the image signal processor  150  compares the amplitudes of the digital signals and may determine the directions in which the direction lines of the edge blocks are directed. The image signal processor  150  may determine the direction line of the edge block as a horizontal line parallel to the X axis, a vertical line parallel to the Y axis, or an inclined line (grade line or slope) between the horizontal line and the vertical line. Herein, the angle between the inclined line and the horizontal line may be greater than 0° and less than 180°. The number of inclined lines determined by the image signal processor  150  may be at least one. 
     In operation S 150 , the image signal processor  150  may extract the edges of the image by connecting the direction lines of the edge blocks. The image signal processor  150  may output the extracted edge information to the outside of the image sensor  100 . 
       FIG. 4  is a flowchart illustrating an example of detailed operations of operation S 130  of  FIG. 3 .  FIG. 4  will be described with reference to  FIGS. 1  to 3. 
     In operation S 131 , the image signal processor  150  may determine whether the sum of the amplitudes of the digital signals belonging to each of the blocks is greater (higher) than or equal to a first reference value. For example, the image signal processor  150  may include a comparator and at least one register that stores a sum of the amplitudes of the digital signals belonging to each of the blocks and a first reference value. At least one of the register may be included in a memory device (e.g., cache memory, main memory, etc.) located outside the image signal processor  150 . The first reference value may be preset by the image signal processor  150 . If the sum of the amplitudes of the digital signals belonging to each of the blocks is equal to or larger than the first reference value, operation S 132  is performed. If not, operation S 134  proceeds. 
     In operation S 132 , the image signal processor  150  may determine whether the sum of the amplitudes of the digital signals belonging to each of the blocks is less (lower) than a second reference value. For example, the image signal processor  150  may further include a register for storing the second reference value. The second reference value may be preset by the image signal processor  150 . If the sum of the amplitudes of the digital signals belonging to each of the blocks is less than the second reference value, operation S 134  is performed. If not, operation S 135  proceeds. 
     In operation S 133 , the image signal processor  150  may determine that the blocks whose sum of the amplitudes of the digital signals is less than the first reference value do not have direction lines. That is, the image signal processor  150  may not determine the direction lines of the blocks in operation S 133 . Even if the image is not located in the blocks in operation S 133  or the edge of the image is located in the blocks in operation S 133 , the amplitudes of the image signals generated in the blocks may be very small. Thus, the image signal processor  150  may set the first reference value based on the accuracy of edge extraction of the image. 
     In operation S 134 , the image signal processor  150  may determine the blocks whose sum of the amplitudes of the digital signals is greater than or equal to the first reference value and is less than the second reference value as the edge blocks. That is, the image signal processor  150  may determine the directions in which the direction lines of the blocks in operation S 134  are directed. The edges of the image may be located in the blocks in operation S 134 . The amplitudes of the image signals generated in any block where the edge of the image is located may be less than the amplitudes of the image signals generated in other blocks located within the edge of the image. Thus, the image signal processor  150  may set the second reference value based on the accuracy of edge extraction of the image. 
     In operation S 135 , the image signal processor  150  may determine that the blocks whose sum of the amplitudes of the digital signals is greater than or equal to the second reference value have direction lines that may be directed in all directions. The blocks in operation S 135  may be omnidirectional blocks. The image signal processor  150  may determine the directions in which the direction lines of the blocks in operation S 135  are directed based on the sum of the amplitudes of the digital signals of the blocks adjacent to each of the blocks in operation S 135 . Alternatively, the image signal processor  150  may determine that the blocks in operation S 135  are located within the edge of the image and may not determine the direction lines of the blocks in operation S 135 . 
     In an embodiment, if there are edge blocks in operation S 134  among the blocks adjacent to the arbitrary first block in operation S 135 , the image signal processor  150  may determine the direction in which the direction line of the first block is directed based on the direction lines of the edge blocks in operation S 134 . In this case, the first block may be an edge block. The image signal processor  150  may determine the direction in which the direction line of the first block is directed, for connecting the direction lines of the blocks in operation S 134 . 
     In another embodiment, if the sum of the amplitudes of the digital signals of all the blocks adjacent to the arbitrary second block in operation S 135  (i.e., all the blocks surrounding the second block) is greater than or equal to the second reference value, the image signal processor  150  may not determine the direction in which the direction line of the second block is directed. In this case, the second block may not be located at the edge of the image, but may be located on the surface within the edge of the image. That is, the second block may not be an edge block. 
     In summary, the image signal processor  150  may not determine the direction line of the block corresponding to Equation 1. The image signal processor  150  may determine the direction in which the direction line of the block corresponding to Equation 2 is directed. The image signal processor  150  may determine that the direction line of the block corresponding to Equation 3 may be directed in all directions. Equations 1 to 3 are as follows. In Equations 1 to 3, B may represent a block, i and j may represent relative coordinate values on the Y and X axes, and n may be determined based on the size of the block. 
     
       
         
           
             
               
                 
                   
                       
                   
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       FIG. 5  illustrates an example in which an image signal processor determines blocks that partition a pixel array according to operation S 130  of  FIG. 3 , including operations S 131  to S 135  of  FIG. 4 .  FIG. 5  will be described with reference to  FIGS. 1  to 4. 
     In  FIG. 5 , it is assumed that the converter  140  converts the image signals output from the pixels of the pixel array  110  into 1-bit digital signals (for example, the above-described k is 1). The minimum and maximum values of the digital signal may be “0” and “1”, respectively. It is assumed that the block contains 2×2 pixels. In this assumption, the minimum and maximum values of the sum of the amplitudes of the digital signals of one block may be “0” and “4”. 
     In an embodiment, the image signal processor  150  may divide the blocks partitioning the pixel array  110  into an N block area  111 , an edge block area  112 , and an A block area  113  based on the sum of the amplitudes of the digital signals belonging to the block. In the N block region  111 , blocks whose sum of the amplitudes of the digital signals is less than the first reference value may be located. Here, N is an abbreviation of “Null”. The image signal processor  150  may not determine the direction lines of the blocks located in the N block area  111  (see operation S 133  of  FIG. 4 ). In the edge block area  112 , edge blocks whose sum of amplitudes of the digital signals is greater than or equal to the first reference value and is less than the second reference value may be located. The image signal processor  150  may determine the directions in which the direction lines of the blocks located in the edge block area  112  is directed (refer to operation S 134  of  FIG. 4 ). In the A block area  113 , blocks whose sum of amplitudes of digital signals is greater than or equal to the second reference value may be located. Here, A is an abbreviation of “All”. The image signal processor  150  may determine that the direction lines of the blocks located in the edge block area  113  may be directed in all directions (refer to operation S 135  of  FIG. 4 ). 
     For example, the image signal processor  150  may set the first reference value to 50% of the maximum value of the sum of the amplitudes of the digital signals of the block. The image signal processor  150  may set the second reference value to 75% of the maximum value of the sum of the amplitudes of the digital signals of the block. According to the above assumption, since the maximum value of the sum of the amplitudes of the digital signals of one block is 4, the first reference value may be 2 and the second reference value may be  3 . The above-described numerical values are all exemplary. 
     Referring to  FIG. 5 , blocks whose sum of the amplitudes of digital signals is 0 or 1 may be located in the N block area  111 . Blocks whose sum of the amplitudes of digital signals is 2 may be located in the edge block area  112 . Blocks whose sum of the amplitudes of digital signals is 3 or 4 may be located in the A block area  113 . 
     In the description of  FIG. 5 , it is assumed that the converter  140  converts the image signals output from the pixels of the pixel array  110  into 1-bit digital signals. The converter  140  may convert the image signals into digital signals of bits other than one bit. For example, the converter  140  may convert image signals to 3-bit digital signals, and the image signal may be quantized in 8 operations. According to an embodiment of the inventive concept, the image signal processor  150  may allocate codes of 0, 1, 2, 3, and 4 to the digital signals quantized in 8 operations. Specific examples of code allocation are described with reference to Table 1. 
     
       
         
           
               
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                 Amplitude of 3-bit 
                   
                   
                   
               
               
                 digital signal 
                 Signal amplitude [%] 
                 Code allocation 
                 Error [%] 
               
               
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                 000 
                 0 
                 0 
                 0 
               
               
                 001 
                 14 
                 1 
                 11 
               
               
                 010 
                 28 
                 1 
                 3 
               
               
                 011 
                 43 
                 2 
                 7 
               
               
                 100 
                 57 
                 2 
                 7 
               
               
                 101 
                 71 
                 3 
                 4 
               
               
                 110 
                 86 
                 3 
                 11 
               
               
                 111 
                 100 
                 4 
                 0 
               
               
                   
               
            
           
         
       
     
     In Table 1, 5 codes of 5 operations may be allocated to the amplitude of a 3-bit digital signal quantized in 000 to 111. Since codes of 5 operations are allocated to the digital signals quantized in 8 operations, an error may exist. In an embodiment, if the image signal processor  150  uses a 3-bit digital signal quantized in 000 to 111 as is, there may be no error in Table 1. As the number of allocated codes is decrease, the error may increase, but the time required for the image signal processor  150  to extract an edge of the image may be reduced. 
     In the example of Table 1, the digital signal converted by the converter  140  from one pixel may have an amplitude from 0 to 4. If the block includes 2×2 pixels, the minimum and maximum values of the sum of the amplitudes of the digital signals of the block may be “0” and “16”, respectively. In this case, the first reference value may be 8 which is 50% of the maximum value of the sum of the amplitudes of the digital signals of the block, and the second reference value may be 12 which is 75% of the maximum value of the sum of the amplitudes of the digital signals of the block. Hereinafter, a specific example in which the image signal processor  150  determines an edge of an image will be described. 
       FIGS. 6 to 8  illustrate an example in which an edge of an image is determined according to an embodiment of the inventive concept.  FIGS. 6 to 8  will be described together and will be described with reference to  FIGS. 1, 3, 4, and 5 . 
     Referring to  FIG. 6 , the pixel array  110  may include 12×12 pixels arranged along the X and Y axes. The pixel array  110  may be partitioned by 6×6 blocks arranged along the X and Y axes. The sizes of the blocks are equal to each other and each of the blocks may include 2×2 pixels. For example, optical signals based on the image number of “2” may be incident on the pixel array  110 . 
     Referring to  FIG. 7 , the image signal processor  150  may determine the direction lines of the edge blocks among the 6×6 blocks based on the sum of the amplitudes of the digital signals of each of the 6×6 blocks (refer to operation S 130  in  FIG. 3 ). For example, the image signal processor  150  may determine that the direction line of the edge block is directed to any one of 0°, 45°, 90°, and 135° with respect to the X axis. The detailed operations of the image signal processor  150  to determine the direction in which the direction line of the edge block is directed will be described later with reference to  FIGS. 10 to 21 . Here, the values and the numbers of angles of the direction line that the image signal processor  150  may select are all exemplary. 
     Each of the 6×6 blocks may output image signals based on the image. For example, each of the sums of the amplitudes of the digital signals of the blocks B 16 , B 21 , B 22 , B 23 , B 24 , B 26 , B 31 , B 32 , B 33 , B 34 , B 36 , B 41 , B 45 , B 46 , B 51 , B 53 , B 54 , B 55 , B 56 , B 61 , and B 66  among the 6×6 blocks may be less than the first reference value (e.g., 50%). Each of the sums of the amplitudes of the digital signals of the blocks B 11 , B 12 , B 13 , B 14 , B 15 , B 25 , B 35 , B 42 , B 43 , B 44 , B 52 , B 63 , B 64 , and B 65  among the 6×6 blocks may be greater than or equal to the first reference value and may be less than the second reference value (e.g., 75%). The sum of the amplitudes of the digital signals of the block B 62  among the 6×6 blocks may be greater than or equal to the second reference value (e.g., 75%). 
     The image signal processor  150  determines that the blocks B 16 , B 21 , B 22 , B 23 , B 24 , B 26 , B 31 , B 32 , B 33 , B 34 , B 36 , B 41 , B 45 , B 46 , B 51 , B 53 , B 54 , B 55 , B 56 , B 61 , and B 66  among the 6×6 blocks belong to the N block area  111  of  FIG. 5  and does not determine the direction lines of the blocks (refer to operation S 133  of  FIG. 4 ). The image signal processor  150  determines that the blocks B 11 , B 12 , B 13 , B 14 , B 15 , B 25 , B 35 , B 42 , B 43 , B 44 , B 52 , B 63 , B 64 , and B 65  among the 6×6 blocks belong to the edge block area  112  of  FIG. 5  and respectively determine the direction lines of the blocks (refer to operation S 134  of  FIG. 4 ). The image signal processor  150  determines that the block B 62  among the 6×6 blocks belongs to the A block area  113  of  FIG. 5  and that the direction line of the block may be directed to all directions (refer to operation S 135  of  FIG. 4 ). 
     In the embodiment, the image signal processor  150  may determine the direction in which the direction line of the block B 62  is directed based on the direction lines of the other edge blocks B 52  and B 63  adjacent to the block B 62 . The image signal processor  150  may determine the direction line of the edge block B 52  as 90° and the direction line of the edge block B 63  as 0°. Accordingly, the image signal processor  150  may determine the direction line of the block B 62  as 135° so as to connect the direction line of the edge block B 52  and the direction line of the edge block B 63 . 
       FIG. 8  exemplarily shows direction lines of edge blocks among 6×6 blocks determined by the image signal processor  150 . For example, the direction line may correspond to any one of 0°, 45°, 90°, and 135° with respect to the X axis. The image signal processor  150  according to the embodiment of the inventive concept may position the direction line so that the direction line passes through the center of the block even if the image is located at a non-center portion in the block. Referring to  FIG. 8 , the image signal processor  150  may determine and reconstruct the edge of the image number of “2” in  FIG. 6 . 
       FIG. 9  illustrates an example in which the pixel arrays of  FIG. 1  are partitioned into blocks that overlap each other according to an embodiment of the inventive concept.  FIG. 9  will be described with reference to  FIGS. 1 and 6 to 8 . 
     Referring to  FIGS. 6 to 8 , the pixel array  110  may be partitioned by 6×6 blocks that do not overlap with each other. According to an embodiment of the inventive concept, the blocks partitioning the pixel array  110  may overlap each other. 
     In other words, the blocks may share at least one pixel. Referring to  FIG. 9 , the pixel array  110  may be partitioned into blocks that each include 2×2 pixels and overlap each other. 
     The image signal processor  150  may calculate the sum of the amplitudes of the digital signals of each of the blocks overlapping each other and determine the directions in which the direction lines of the edge blocks are directed based on the sum. For example, the image signal processor  150  may respectively determine the direction lines of the first to third blocks located along the X axis according to operation S 140  in  FIG. 4 . The direction line of the second block may be further determined by the image signal processor  150 . Therefore, the direction line of the second block is further determined more than when the image signal processor  150  determines only the direction lines of the first and third blocks, so that the edges of the image may be extracted more precisely. 
       FIG. 10  is a flowchart illustrating an example of detailed operations of operation S 140  of  FIG. 3 .  FIG. 10  will be described with reference to  FIGS. 1  to 3.  FIG. 10  will be described together with reference to the specific examples shown in  FIGS. 11 to 14 . In  FIG. 10 , it is assumed that each of the blocks partitioning the pixel array  110  includes 2×2 pixels P 11 , P 12 , P 21 , and P 22 . Then, the X-axis direction is the first direction and the Y-axis direction is the second direction. It is assumed that the amplitude of the digital signal converted by the converter  140  from one pixel in  FIGS. 11 to 14  is 0 to 4. 
     In operation S 141 , the image signal processor  150  may determine whether the amplitudes of the first direction signals and the second direction signals are the same or equal to each other. In operation S 141 , the image signal processor  150  may perform an operation based on Equation 4.
 
| P 11|=| P 12|=| P 21|=| P 22|  [Equation 4]
 
     For example, the image signal processor  150  may include at least one register that stores each of the amplitudes of the first direction signals and the second direction signals. If the amplitudes of the first direction signals and the second direction signals are equal to each other, operation S 142  may be performed. If not, operation S 143  proceeds. 
     The converter  140  may convert the image signals output from the pixels P 11  and P 12  arranged in the first direction into the first direction signals. The converter  140  may convert the image signals output from the pixels P 21  and P 22  arranged in the first direction into the first direction signals. For example, the pixels arranged along the first direction may have the same coordinate value in the second direction. 
     The converter  140  may convert the image signals output from the pixels P 21  and P 11  arranged in the second direction into the second direction signals. The converter  140  may convert the image signals output from the pixels P 22  and P 12  arranged in the second direction into second direction signals. For example, the pixels arranged along the second direction may have the same coordinate value in the first direction. 
     In operation S 142 , the image signal processor  150  may determine that the direction line is directed in all directions.  FIGS. 11 and 12  exemplarily illustrate edge blocks having the same amplitudes of the first direction signals and the second direction signals. Referring to  FIG. 11 , an image may be uniformly positioned on 2×2 pixels P 11 , P 12 , P 21 , and P 22 . The image shown in  FIG. 11  may be part of any image or may be itself. The amplitude of the digital signal output from each of the 2×2 pixels P 11 , P 12 , P 21 , and P 22  and converted by the converter  140  may be, for example, 2. Since the amplitudes of the first direction signals and the second direction signals are 2, the image signal processor  150  may determine that the direction line of the edge block  116 _ 1  may be directed in all directions. 
     Referring to  FIG. 12 , an image may be uniformly positioned on 2×2 pixels P 11 , P 12 , P 21 , and P 22 . The image shown in  FIG. 12  may be part of any image or may be itself. Although the image of  FIG. 12  differs from the image of  FIG. 11 , the amplitude of the digital signal output from each of the 2×2 pixels P 11 , P 12 , P 21 , and P 22  and converted by the converter  140  may be, for example, 2. Since the amplitudes of the first direction signals and the second direction signals are 2, the image signal processor  150  may determine that the direction line of the edge block  116 _ 2  may be directed in all directions. 
     In an embodiment, in operation S 142 , the image signal processor  150  determines that the direction line is directed in all directions and then determines the direction in which the direction line of the block in step S 142  is directed based on the direction line of any block adjacent to the block in operation S 142 . 
     In operation S 143 , the image signal processor  150  may determine whether the amplitudes of the first direction signals are equal to each other. In operation S 143 , the image signal processor  150  may perform an operation based on Equation 5.
 
(| P 11|=| P 12|)∩(| P 21|=| P 22|)  [Equation 5]
 
     If the amplitudes of the first direction signals are equal to each other, operation S 144  may be performed. If not, operation S 145  proceeds. 
     In operation S 144 , the image signal processor  150  may determine that the direction line of the edge block is directed in the first direction.  FIG. 13  exemplarily shows edge blocks having the same amplitudes of the first direction signals. The image may be formed along the first direction. The line width of the image may be varied, for example, 8, 10, 12, and the like, as shown in  FIG. 13 . Regardless of the line width of the image shown in  FIG. 13 , the amplitudes of the first direction signals output from the pixels P 21  and P 22  arranged along the first direction and converted by the converter  140  may be equal to each other as 4. If the line width of the image shown in  FIG. 13  is 10, the amplitudes of the first direction signals output from the pixels P 11  and P 12  arranged along the first direction and converted by the converter  140  may be equal to each other as 1. Similarly, if the line width of the image shown in  FIG. 13  is 12, the amplitudes of the first direction signals output from the pixels P 11  and P 12  arranged along the first direction and converted by the converter  140  may be equal to each other as 2. Accordingly, the image signal processor  150  may determine that the direction line of the edge block  117 _ 1  is directed in the first direction. 
     In operation S 145 , the image signal processor  150  may determine whether the amplitudes of the second direction signals are equal to each other. In operation S 145 , the image signal processor  150  may perform an operation based on Equation 6.
 
(| P 11|=| P 21|)∩(| P 12|=| P 22|)  [Equation 6]
 
     If the amplitudes of the second direction signals are equal to each other, operation S 146  may be performed. If not, the next operation (operation S 147  of  FIG. 15 ) may proceed. 
     In operation S 146 , the image signal processor  150  may determine that the direction line of the edge block is directed in the second direction.  FIG. 14  exemplarily shows edge blocks having the same amplitudes of the second direction signals. The image may be formed along the second direction. The line width of the image may be varied, for example, 8, 10, 12, and the like, as shown in  FIG. 14 . 
     Regardless of the line width of the image shown in  FIG. 14 , the amplitudes of the second direction signals output from the pixels P 21  and P 11  arranged along the second direction and converted by the converter  140  may be equal to each other as 4. If the line width of the image shown in  FIG. 14  is 10, the amplitudes of the second direction signals output from the pixels P 22  and P 12  arranged along the second direction and converted by the converter  140  may be equal to each other as 1. Similarly, if the line width of the image shown in  FIG. 14  is 12, the amplitudes of the second direction signals output from the pixels P 22  and P 12  arranged along the second direction and converted by the converter  140  may be equal to each other as 2. Accordingly, the image signal processor  150  may determine that the direction line of the edge block  117 _ 2  is directed in the second direction. 
     In the embodiment, the order of operations S 141 , S 143 , and S 145  is not limited to that shown in  FIG. 10 . 
     Referring to  FIGS. 10 to 14 , the order in which the image signal processor  150  determines whether the direction line of the edge block is directed to the first direction or the second direction (i.e., whether the direction line is the horizontal direction or the vertical direction) is described. Referring to  FIGS. 15 to 21 , operations of the image signal processor  150  to determine the direction in which the direction line is directed in the direction other than the first direction and the second direction will be described. 
       FIG. 15  is a flowchart illustrating an example of detailed operations of operation S 140  of  FIG. 3 .  FIG. 15  will be described with reference to  FIGS. 1  to 3.  FIG. 15  will be described together with reference to the specific examples shown in  FIGS. 16 to 21 . In  FIG. 15 , it is assumed that each of the blocks partitioning the pixel array  110  includes 2×2 pixels P 11 , P 12 , P 21 , and P 22 . Then, the X-axis direction is the first direction and the Y-axis direction is the second direction. It is assumed that the amplitude of the digital signal converted by the converter  140  from one pixel in  FIGS. 15 to 21  is 0 to 4. 
     The direction line of the edge block may not be determined through operations S 141  to S 146  of  FIG. 10 . In this case, the direction line of the edge block may be directed in a direction other than the first direction or the second direction. The other direction may be, for example, a third direction or a fourth direction. The angle between the third direction and the first direction may be 45°. The angle between the fourth direction and the first direction may be 135°. In an embodiment, the image signal processor  150  may further determine other directions having different angles as well as the first to fourth directions. 
     In operation S 147 , the image signal processor  150  may determine whether the sum of the amplitudes of the third direction signals is greater than the sum of the amplitudes of the fourth direction signals. The converter  140  may convert the image signals output from the pixels P 21  and P 12  arranged in the third direction into the third direction signals. The converter  140  may convert the image signals output from the pixels P 22  and P 11  arranged in the fourth direction into the fourth direction signals. The image signal processor  150  may perform an operation based on Equation 7.
 
(| P 21|=| P 23|)&gt;(| P 22|=| P 11|)  [Equation 7]
 
     For example, the image signal processor  150  may include at least one register that stores each of the amplitudes of the third direction signals and the fourth direction signals. If the sum of the amplitudes of the third direction signals is greater than the sum of the amplitudes of the fourth direction signals, operation S 148  may be performed. If not, operation S 149  may proceed. 
     In operation S 148 , the image signal processor  150  may determine that the direction line of the edge block is directed in the third direction.  FIG. 16  exemplarily shows an edge block in which the sum of the amplitudes of the third direction signals is greater than the sum of the amplitudes of the fourth direction signals. The image may be formed along the third direction. The sum of the amplitudes of the third direction signals output from the pixels P 21  and P 12  arranged along the third direction and converted by the converter  140  may be 8. The sum of the amplitudes of the fourth direction signals output from the pixels P 22  and P 11  arranged along the fourth direction and converted by the converter  140  may be 4. Accordingly, the image signal processor  150  may determine that the direction line of the edge block  118 _ 1  is directed in the third direction. 
     In operation S 149 , the image signal processor  150  may determine whether the sum of the amplitudes of the fourth direction signals is greater than the sum of the amplitudes of the third direction signals. The image signal processor  150  may perform an operation based on Equation 8.
 
(| P 22|=| P 11|)&gt;(| P 21|=| P 12|)  [Equation 8]
 
     If the sum of the amplitudes of the fourth direction signals is greater than the sum of the amplitudes of the third direction signals, operation S 150  may be performed. If not, operation S 151  proceeds. 
     In operation S 150 , the image signal processor  150  may determine that the direction line of the edge block is directed in the fourth direction.  FIG. 17  exemplarily shows an edge block in which the sum of the amplitudes of the fourth direction signals is greater than the sum of the amplitudes of the third direction signals. The image may be formed along the fourth direction. The sum of the amplitudes of the fourth direction signals output from the pixels P 22  and P 11  arranged along the fourth direction and converted by the converter  140  may be 8. The sum of the amplitudes of the third direction signals output from the pixels P 21  and P 12  arranged along the third direction and converted by the converter  140  may be 4. Accordingly, the image signal processor  150  may determine that the direction line of the edge block  118 _ 2  is directed in the fourth direction. 
     In operation S 151 , the sum of the amplitudes of the third direction signals may be equal to the sum of the amplitudes of the fourth direction signals. The image signal processor  150  may determine whether the sum of the amplitudes of the direction signals of the upper pixels is greater than the sum of the amplitudes of the direction signals of the lower pixels. 
     The upper pixels may be disposed above the lower pixel along the second direction. The coordinate value in the second direction of the upper pixels may be greater than the coordinate value in the second direction of the lower pixels. The coordinate value on the first direction of the upper pixels may be the same as the coordinate value on the first direction of the lower pixels. For example, the upper pixels may be pixels P 11  and P 12  (e.g., may be referred to as first sub-pixels), and the lower pixels may be pixels P 21  and P 22  (e.g., referred to as second sub-pixels). The direction signals of the upper pixels are digital signals that are output from the upper pixels P 11  and P 12  and may be converted by the converter  140 . The direction signals of the lower pixels are digital signals that are output from the lower pixels P 21  and P 22  and may be converted by the converter  140 . The image signal processor  150  may perform an operation based on Equation 9.
 
(| P 11|=| P 12|)&gt;(| P 21|=| P 22|)  [Equation 9]
 
     If the sum of the amplitudes of the direction signals of the upper pixels is greater than the sum of the amplitudes of the direction signals of the lower pixels, operation S 152  may be performed. If not, operation S 155  proceeds. 
     In operation S 152 , the image signal processor  150  may determine whether the amplitude of the direction signal of the left pixel is greater than the amplitude of the direction signal of the right pixel. The right pixel may be disposed on the right of the left pixel along the first direction. The coordinate value in the first direction of the right pixel may be greater than the coordinate value in the first direction of the left pixel. The coordinate value in the second direction of the right pixel may be the same as the coordinate value in the second direction of the left pixel. For example, the left pixel and the right pixel may be pixels P 11  and P 12  arranged along the first direction, respectively. Alternatively, the left pixel and the right pixel may be pixels P 21  and P 22  arranged along the first direction, respectively. The image signal processor  150  may perform an operation based on Equation 10.
 
(| P 11|&gt;| P 12|)∩(| P 21|&gt;| P 22|)  [Equation 10]
 
     If the amplitude of the direction signal of the left pixel is greater than the amplitude of the direction signal of the right pixel, operation S 153  may be performed. If not, operation S 154  proceeds. 
     In operation S 153 , the image signal processor  150  may determine that the direction line of the edge block is directed in the third direction.  FIG. 18  exemplarily shows an edge block in which the sum of the amplitudes of the direction signals of the upper pixels is greater than the sum of the amplitudes of the direction signals of the lower pixels and the amplitude of the direction signal of the left pixel is greater than the amplitude of the direction signal of the right pixel. The image may be formed along the third direction. However, the image of  FIG. 18  may be located above the image of  FIG. 16  with respect to the second direction. 
     Referring to  FIG. 18 , the sum of the amplitudes of the direction signals of the upper pixels P 11  and P 12  may be 6. The sum of the amplitudes of the direction signals of the lower pixels P 21  and P 22  may be 2. The amplitude of the direction signal of the left pixel P 11  may be 4. The amplitude of the direction signal of the right pixel P 12  may be 2. The amplitude of the direction signal of the left pixel P 21  may be 2. The amplitude of the direction signal of the right pixel P 22  may be 0. Accordingly, the image signal processor  150  may determine that the direction line of the edge block  118 _ 3  is directed in the third direction. 
     In operation S 154 , the image signal processor  150  may determine that the direction line of the edge block is directed in the fourth direction.  FIG. 19  exemplarily shows an edge block in which the sum of the amplitudes of the direction signals of the upper pixels is greater than the sum of the amplitudes of the direction signals of the lower pixels and the amplitude of the direction signal of the right pixel is greater than the amplitude of the direction signal of the left pixel. The image may be formed along the fourth direction. However, the image of  FIG. 19  may be located above the image of  FIG. 17  based on the second direction. 
     Referring to  FIG. 19 , the sum of the amplitudes of the direction signals of the upper pixels P 11  and P 12  may be 6. The sum of the amplitudes of the direction signals of the lower pixels P 21  and P 22  may be 2. The amplitude of the direction signal of the left pixel P 11  may be 2. The amplitude of the direction signal of the right pixel P 12  may be 4. The amplitude of the direction signal of the left pixel P 21  may be 0. The amplitude of the direction signal of the right pixel P 22  may be 2. Accordingly, the image signal processor  150  may determine that the direction line of the edge block  118 _ 4  is directed in the fourth direction. 
     In operation S 155 , the image signal processor  150  may determine whether the amplitude of the direction signal of the left pixel is greater than the amplitude of the direction signal of the right pixel. Operation S 155  may be the same as operation S 152 . If the amplitude of the direction signal of the left pixel is greater than the amplitude of the direction signal of the right pixel, operation S 156  may be performed. If not, operation S 157  proceeds. 
     In operation S 156 , the image signal processor  150  may determine that the direction line of the edge block is directed in the third direction.  FIG. 20  exemplarily shows an edge block in which the sum of the amplitudes of the direction signals of the lower pixels is greater than the sum of the amplitudes of the direction signals of the upper pixels and the amplitude of the direction signal of the left pixel is greater than the amplitude of the direction signal of the right pixel. The image may be formed along the fourth direction. However, the image of  FIG. 20  may be located further below the image of  FIG. 17  based on the second direction. 
     Referring to  FIG. 20 , the sum of the amplitudes of the direction signals of the upper pixels P 11  and P 12  may be 2. The sum of the amplitudes of the direction signals of the lower pixels P 21  and P 22  may be 6. The amplitude of the direction signal of the left pixel P 11  may be 2. The amplitude of the direction signal of the right pixel P 12  may be 0. The amplitude of the direction signal of the left pixel P 21  may be 4. The amplitude of the direction signal of the right pixel P 22  may be 2. Accordingly, the image signal processor  150  may determine that the direction line of the edge block  118 _ 5  is directed in the fourth direction. 
     In operation S 157 , the image signal processor  150  may determine that the direction line of the edge block is directed in the third direction.  FIG. 21  exemplarily shows an edge block in which the sum of the amplitudes of the direction signals of the lower pixels is greater than the sum of the amplitudes of the direction signals of the upper pixels and the amplitude of the direction signal of the right pixel is greater than the amplitude of the direction signal of the left pixel. The image may be formed along the third direction. However, the image of  FIG. 21  may be located further below the image of  FIG. 16  based on the second direction. 
     Referring to  FIG. 21 , the sum of the amplitudes of the direction signals of the upper pixels P 11  and P 12  may be 2. The sum of the amplitudes of the direction signals of the lower pixels P 21  and P 22  may be 6. The amplitude of the direction signal of the left pixel P 11  may be 0. The amplitude of the direction signal of the right pixel P 12  may be 2. The amplitude of the direction signal of the left pixel P 21  may be 2. The amplitude of the direction signal of the right pixel P 22  may be 4. Accordingly, the image signal processor  150  may determine that the direction line of the edge block  118 _ 6  is directed in the third direction. 
     The image signal processor  150  according to the embodiment of the inventive concept may determine the direction lines of the blocks  118 _ 1  and  118 _ 2  when the image is located at the center in the blocks  118 _ 1  and  118 _ 2  in  FIGS. 16 and 17 . Also, even if the image is not located at the center in the blocks  118 _ 3  to  118 _ 6  in  FIGS. 18 and 21 , the image signal processor  150  may determine the direction lines of the blocks  118 _ 3  to  118 _ 6 , respectively. The image signal processor  150  may place the direction line at the center of the block, regardless of whether the image is located at the center in the block. 
       FIGS. 22 and 23  illustrate an example in which an edge of an image is extracted according to an embodiment of the inventive concept. For example, optical signals based on an image of a triangular shape may be incident on the pixel array  110 . 
     Referring to  FIG. 22 , pixels of the pixel array  110  may generate image signals based on the triangular shaped image. The converter  140  may convert these image signals into digital signals. The sum of the amplitudes of the digital signals of each of the blocks corresponding to the outside of the image of the triangular shape may be less than the first reference value. The sum of the amplitudes of the digital signals of each of the blocks corresponding to the edges of the triangular shaped image may be greater than or equal to a first reference value and may be less than the second reference value. The sum of the amplitudes of the digital signals of each of the blocks corresponding to the inside of the image of the triangular shape may be greater than or equal to the second reference value. The image signal processor  150  may classify blocks that partition the pixel array  110  into a block having no direction line, an edge block E having a direction line, and a block A having a direction line that may be directed in all directions based on operation S 130  of  FIG. 3  including operations S 131  to S 135  of  FIG. 4  Then, the image signal processor  150  may determine the direction of the direction line of the edge block E based operation S 140  of  FIG. 3  including operations S 141  to S 146  of  FIG. 10  and operations S 147  to S 157  of  FIG. 15 . 
       FIG. 23  exemplarily shows the edge of the triangular-shaped image extracted according to operations S 130  and S 140  in  FIG. 3 . If the adjacent blocks of a block A may have directional lines that may be directed in all directions of A (i.e., if the sum of the amplitudes of the digital signals of the adjacent blocks is greater than or equal to the second reference value), the image signal processor  150  may determine that the block A does not have a direction line corresponding to an edge of the image. 
       FIG. 24  exemplarily illustrates a process of hierarchically extracting edges of an image according to another embodiment of the inventive concept.  FIG. 24  will be described with reference to  FIGS. 1 and 3 . 
     As described above, the pixel array  110  of  FIG. 1  may include pixels arranged along the X and Y axes. Referring to  FIG. 24 , in the first layer, the pixel array  110  may be partitioned into blocks each including 2×2 pixels. Also, in the second layer, the pixel array  110  may be partitioned into hyper cells (HCs) each including 2×2 blocks. Here, the size of the block and the size of the hyper cell are not limited to the above-described values, and may be determined based on the user&#39;s request, image resolution, edge precision, edge extraction speed, and the like. 
     The direction lines of the blocks of the hyper cell may be determined by the image signal processor  150  based on operation S 130  of  FIG. 3  including operations S 131  to S 135  of  FIG. 4 , and operation S 140  of  FIG. 3  including operations S 141  to S 146  of  FIG. 10  and operations S 147  to S 157  of  FIG. 15 . The image signal processor  150  may include at least one counter configured to count the directions of the direction lines of the blocks of the hyper cell. The image signal processor  150  may determine the direction in which the direction line of the hyper cell is directed based on the counting result. The image signal processor  150  may determine the direction in which the direction line of the hyper cell is directed based on a majority operation. 
     For example, if the direction lines of the blocks of the hyper cell are 0°, 0°, 0°, and 90°, respectively, the image signal processor  150  may select the direction line of the hyper cell as 0°. If the direction lines of the blocks of the hyper cell are 0°, 45°, 90°, and 135°, respectively (i.e., when the frequency numbers indicating the first to fourth directions are the same), the image signal processor  150  may determine that there is no direction line of the hyper cell. 
     In an embodiment, the hyper cells shown in  FIG. 24  may be the first hyper cells, and the pixel array  110  may be partitioned into second hyper cells (not shown), each of which includes at least four first hyper cells, in a third layer (not shown). The image signal processor  150  may determine the direction in which the direction line of the second hyper cell is directed in a manner similar to that of the first hyper cell. As the layer in which the pixel array  110  is partitioned increases, the edge precision may be reduced, but the edge extraction speed may increase. 
       FIGS. 25 and 26  illustrate a process of extracting a motion of an image according to another embodiment of the inventive concept.  FIGS. 25 and 26  will be described together and will be described with reference to  FIGS. 1 and 3 . In  FIG. 25 , the pixel array  110  may be partitioned into hyper cells of an arbitrary size. 
     The image signal processor  150  may extract the edges of the image at the time points t 1 , t 2 , and t 3 , respectively, based on operation S 130  of  FIG. 3  including operations S 131  to S 135  of  FIG. 4 , operation S 140  of  FIG. 3  including operations S 141  to S 146  of  FIG. 10  and operations S 147  to S 157  of  FIG. 15 , and the direction line determination method of the hyper cell described above with reference to  FIG. 25 . The image signal processor  150  may compare the image edges of the time points t 1 , t 2 , and t 3  and may determine the motion of the image over time. The edges of the image extracted at the time points t 1 , t 2 , and t 3  by the image signal processor  150  are shown in  FIG. 25 . The image signal processor  150  may detect the centers of the edges of the image as representative points t 1 , t 2 , and t 3  at the time points t 1 , t 2 , and t 3 . 
     In  FIG. 26 , the pixel array  110  may be partitioned into time cells (TC) having the same physical size as the hyper cell of  FIG. 25 . A time cell has physically the same size as a hyper cell, but may represent hyper cells at different time points. For example, the time cell T 11  may represent a hyper cell H 11  of a time point t 1 , a hyper cell H 11  of a time point t 2 , and a hyper cell H 11  of a time point t 3 . The image signal processor  150  stores the information (e.g., the addresses of the hyper cell, block, and pixel where the representative point is located) on the representative points t 1 , t 2 , and t 3  in  FIG. 25  and writes it in time cells. The image signal processor  150  may determine the motion of the image by connecting the representative points t 1 , t 2 , and t 3  of  FIG. 25  in the time cells. 
       FIG. 27  is a block diagram exemplarily illustrating an image sensor according to another embodiment of the inventive concept. The image sensor  1000  may include a lens  1100 , a filter  1200 , a pixel array  1300 , a converter  1400 , a block memory  1500 , an edge signal processor  1700 , and a timing controller  1800 . 
     The lens  1100  may collect the optical signals reflected from the subject, and the filter  1200  may filter the optical signals incident through the lens  1100 . The filtered optical signals may be provided to the pixel array  1300 . The pixel array  1300 , the converter  1400 , and the timing controller  1800  may be similar to the pixel array  110 , the converter  140 , and the timing controller  160  described above with reference to  FIG. 1 . 
     The block memory  1500  may store the amplitudes of the digital signals of each of the blocks converted by the converter  1400  and the sum thereof. The amplitudes of the digital signals stored in the block memory  1500  may configure an edge map of the image. The block memory  1500  may further store the address information of the pixel array and the address information of the blocks. The address information of the blocks stored in the block memory  1500  may be changed by the edge signal processor  1700 . 
     The edge signal processor  1700  may be the image signal processor  150  described above with reference to  FIG. 1 . The edge signal processor  1700  may extract edge information  1710  based on the digital signals of each of the blocks stored in the block memory  1500 . The edge signal processor  1700  may store the edge information  1710  in the block memory  1500 . 
       FIG. 28  is a block diagram exemplarily illustrating an image sensor according to another embodiment of the inventive concept. The image sensor  2000  includes a lens  2100 , a filter  2200 , a pixel array  2300 , a converter  2400 , a block memory  2500 , a pixel memory  2600 , an edge signal processor  2700 , a timing controller  2800 , and an image signal processor  2900 . The lens  2100 , the filter  2200 , the pixel array  2300 , the converter  2400 , the block memory  2500 , the edge signal processor  2700 , and the timing controller  2800  may be similar to the lens  1100 , the filter  1200 , the pixel array  1300 , the converter  1400 , the block memory  1500 , the edge signal processor  1700 , and the timing controller  1800 , respectively. Compared to the image sensor  1000  of  FIG. 27 , the image sensor  2000  may further include a pixel memory  2600  and an image signal processor  2900 . 
     The pixel memory  2600  may store the amplitude of the digital signal of the pixel that is converted by the converter  1400 . In other words, the pixel memory  2600  may store information of an image in pixel units, and the block memory  2500  may store information of an image in block units. Although not shown in  FIG. 28 , the image sensor  2000  may further include another memory for storing information of an image in hyper cell units or time cell units. 
     According to an embodiment of the invention, the image signal processor  2900  may receive both pixel-by-pixel image information from the pixel memory  2600  and edge information of the image from the edge signal processor  2700 . The image signal processor  2900  may use the edge information of the image to process the image. 
     According to the embodiment of the inventive concept, the amplitudes of the signals output from the pixels may be compared and the edge information of the image may be extracted. The image sensor according to the embodiment of the inventive concept may extract the edge information of the image at a high speed and the power consumption of the image sensor required for the extraction may be reduced. 
     Although the exemplary embodiments of the inventive concept have been described, it is understood that the inventive concept should not be limited to these exemplary embodiments but various changes and modifications may be made by one ordinary skilled in the art within the spirit and scope of the inventive concept as hereinafter claimed.