Abstract:
This invention provides a character recognition apparatus comprising: dictionary storage means for storing a plurality of dictionaries; deriving means for deriving a candidate character and an operation result from a character image data by using a first dictionary stored in said storage means; judging means for judging whether or not if the operation result derived by said deriving means satisfies a predetermined reference value; and controlling means for controlling to recognize said character again by using a second dictionary different from said first dictionary used for deriving said operation result, if said judging means judges that said operation result does not satisfy said reference value.

Description:
This application is a continuation-in-part continuation of application Ser. No. 07/844,862, filed Mar. 2, 1992, now abandoned, which is a continuation-in-part continuation of application Ser. No. 07/544,949 filed Jun. 28, 1990, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a character recognition apparatus providing a plurality of character recognizing methods. 
     2. Related Background Art 
     With the apparatus of this type, a character is cut out from image data and is recognized by using a recognizing method which follows a predetermined algorithm, the recognition results in an output of a candidate character. 
     Since a character has been recognized conventionally by using a recognizing method which follows a predetermined algorithm, the recognition factor can not be improved and it takes a long time in recognizing a character. 
     SUMMARY OF THE INVENTION 
     The present invention eliminates the above-described prior art disadvantages, and provides a character recognition apparatus capable of improving a recognition factor and saving a recognition time. 
     The present invention provides a character recognition apparatus comprising: 
     dictionary storage means for storing a plurality of dictionaries; 
     deriving means for deriving a candidate character and an operation result from a character image data by using a first dictionary stored in said storage means; 
     judging means for judging whether or not the operation result derived by said deriving means satisfies a predetermined reference value; and 
     controlling means for controlling to recognize said character again by using a second dictionary different from said first dictionary used for deriving said operation result, if said judging means judges that said operation result does not satisfy said reference value. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a block diagram showing the structure of a character recognition apparatus according to the embodiment of this invention; 
     FIG. 2 is a flow chart explaining the operation of a character recognition process according to a first embodiment; 
     FIG. 3 is a flow chart explaining the operation of a character recognition process according to a second embodiment; and 
     FIG. 4 is a flow chart explaining the operation of a character recognition process according to a third embodiment. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
      1st Embodiment! 
     Preferred embodiments of this invention will be described in detail with reference to the accompanying drawings. 
     FIG. 1 is a block diagram showing the structure of the character recognition apparatus according to the embodiment. In FIG. 1, an input interface (I/F) 1 receives a character image data from an input device such as an image scanner or tablet. A CPU 2 controls the apparatus in accordance with various programs stored in a ROM 3. ROM 3 stores therein control programs, error processing programs, programs shown as the flow chart in FIG. 2, and other data. As will be described later, ROM 3 stores a reference value which is used for checking the recognition result or operation result of one character by using a first dictionary 5 or second dictionary 6. 
     A RAM 4 is used as a working area for various programs described above, and a temporary saving area during an error processing. RAM 4 stores a character image data inputted from the input I/F 1. 
     The first dictionary 5 is formed by using a first character recognition algorithm, and the second dictionary 6 by using a second character recognition algorithm. The first and second dictionaries 5 and 6 are selectively used upon an instruction from CPU 2. The dictionary may be formed in a detachable storage medium such as an IC memory card, and a user selects a desired card and loads it in the character recognition apparatus. 
     An output I/F 7 outputs a recognition result to an external host computer. 
     The operation of this embodiment will be described next. 
     FIG. 2 is a flow chart used for explaining the operation of the character recognition processing according to the embodiment. 
     An original document is read with an image scanner (not shown), and a character image data is inputted and stored in RAM 4 at an image storage area (step S1). A single character is cut out (step S2). The recognition operation is executed by using the first dictionary 5 (step S3). The difference between the first and second dictionaries 5 and 6 is, for example, that the former has characters used frequently and the latter has characters used less frequently. Alternatively, the first dictionary may be formed by using a simple and fast algorithm, and the second dictionary by using an algorighm which is complex and recognizes a character precisely. The operation result (value) and a candidate character obtained by character recognition are temporarily stored in RAM 4. The operation result is compared with the reference value stored in ROM 3 (step S5). If the operation result satisfies the reference value, the candidate character stored in RAM 4 is outputted via the output I/F to a host computer (not shown)(step S11). The operations starting from step 2 to step S11 are repeated until all characters have been recognized. 
     If it is judged at step S6 that the operation result does not satisfy the reference value, the character recognition using the second dictionary is executed (step S7). The operation result (value) and a candidate character obtained through character recognition at step S7 are stored in RAM 4, and the operation result and the reference value are compared with each other in the similar manner at step S5 (step S9). If the operation result does not satisfy the reference value (step S10), an error message notifying inability of recognition is sent to the host computer (step S12). The processes starting from step S2 are repeated until all characters have been recognized. If the operation result satisfies the reference value (step S10), the candidate character stored in RAM 4 is outputted to the host computer via the output I/F (step S11). The processes starting from step S2 are repeated until all characters have been recognized. 
     In the flow chart shown in FIG. 2, if character recognition is not possible, an error message is sent to the host computer. Instead, a plurality of candidate characters may be sent to the host computer. 
     In the above embodiment, the output of the apparatus is sent to the host computer. This invention is not limited thereto, but the output may be sent to a display device such as a CRT display or a recording apparatus such as a printer. For the case of a display device, a plurality of candidate characters can be displayed as the results of recognition, and a keyboard may be used to select one of candidate characters. 
     Further, in the above embodiment, the first and second dictionaries are used. The invention is not limited thereto, but three or more dictionaries may be used within the scope of this invention. 
      2nd Embodiment! 
     The second embodiment of this invention will be described in detail with reference to the flow chart shown in FIG. 3. 
     The character recognition apparatus of this embodiment has the same structure as shown in the block diagram of FIG. 1 of the first embodiment, and the detailed description for FIG. 1 has been given above, so it is omitted herein. 
     The operation of this embodiment will be described. 
     FIG. 3 is a flow chart used for explaining the operation of the character recognition processing of this embodiment. 
     In FIG. 3 steps S1 to S10 are the same as steps S1 to S10 of FIG. 1, and the detailed description thereof has been given previously, so it is omitted herein. 
     The description will be directed to the processing, which is a characteristic feature of this embodiment, and is executed when the operation results at the first and second character recognition do not become larger than the reference value. 
     If the operation result does not satisfy the reference value at the second character recognition (step S10), CPU 2 judges if the candidate characters at the first and second recognition stored in RAM 4 are the same (step S14). If it is judged that they are the same (step S14), the candidate character is outputted to the host computer via the output I/F 7 (step S11). If it is judged at step S14 that the candidate characters at the first and second recognition are not the same, an error message notifying an inability of recognition is outputted to the host computer via the output I/F 7 (step S12). 
     If a candidate character is outputted (step S11) or an error message is outputted (step S12), CPU 2 judges if the character is the last one to be recognized or not (step S13). The processes starting from step S2 are repeated until all characters have been recognized. 
     In the flow chart shown in FIG. 3, if character recognition is not possible, an error message is sent to the host computer. Instead, a plurality of candidate characters may be sent to the host computer. 
     In the above embodiment, the output of the apparatus is sent to the host computer. This invention is not limited thereto, but the output may be sent to a display device such as a CRT display or a recording apparatus such as a printer. For the case of a display device, a plurality of candidate characters can be displayed as the recognition result, and a keyboard may be used to select one of candidate characters. 
     Further, in the above embodiment, the first and second dictionaries are used. The invention is not limited thereto, but three or more dictionaries may be used within the scope of this invention. 
      3rd Embodiment! 
     The third embodiment of this invention will be described in detail with reference to the flow chart shown in FIG. 4. 
     The character recognition apparatus of this embodiment has the same structure as shown in the block diagram of FIG. 1 of the first embodiment, the detailed description for FIG. 1 has been given above, so it is omitted herein. 
     The operation of this embodiment will be described. 
     FIG. 4 is a flow chart used for explaining the operation of the character recognition processing of this embodiment. 
     In FIG. 4, steps SI to S4 and steps S7 and S8 are the same as corresponding steps of FIG. 1, and the detailed description thereof has been given previously, so it is omitted herein. 
     In this embodiment, CPU 2 judges if the candidate characters at steps S4 and S8 at the first and second recognition stored in RAM 4 are the same (step S14). If it is judged that they are the same, the candidate character is outputted to the host computer via the output I/F 7 (step S11). If it is judged at step S14 that the candidate characters are not the same, the first and second recognition operation results at steps S4 and S8 stored in RAM 4 are compared with the reference value, and the candidate character having the operation result nearer to the reference value is selected (step S15) and outputted as a candidate (step S11). 
     The operation result of recognition or the result of comparison with the reference value may be stored in RAM 4. If a candidate character is outputted (step S11), CPU 2 judges if the character is the last one to be recognized or not (step S13). The processes starting from step S2 to step S10 are repeated until all characters have been recognized. 
     In the flow chart shown in FIG. 4, if character recognition is not possible, an error message is sent to the host computer. Instead, a plurality of candidate characters may be sent to the host computer. 
     In the above embodiment, the output of the apparatus is sent to the host computer. This invention is not limited thereto, but the output may be sent to a display device such as a CRT display or a recording apparatus such as a printer. For the case of a display device, a plurality of candidate characters can be displayed as the recognition result, and a keyboard may be used to select one of candidate characters. 
     Further, in the above embodiment, the first and second dictionaries are used. The invention is not limited thereto, but three or more dictionaries may be used within the scope of this invention.