the preferred embodiments according to the present invention will be explained in detail with reference to the drawings . a first embodiment of the present invention will be explained with reference to the drawings . fig7 is a block diagram for explaining the first embodiment of the present invention . as shown in fig7 according to the first embodiment of the present invention , a cpu ( central processing unit ) 100 for arithmetic processing , data processing and controlling of each unit or the like , an image data memory 400 holding binary - value image data converted from an image signal , which is read from a manuscript by a reading sensor ( not illustrated ), a rom 200 , in which a program 201 a executed by the cpu for encoding image data in conformity with the jbig system and a probability estimation table memory 202 for converting image data into encoded data are disposed and stored , a learning table memory 300 to be referred in order to increase the probability that the color , i . e ., white or black of the encoding target pixel becomes as predicted and a fifo ( first in first out ) memory 500 are connected each other in an interior of a jbig system encoding processing apparatus 700 through a bus 600 . the learning table memory 300 , the image data memory 400 , and fifo memory 500 are comprised of ram ( random access memory ). rams 300 through 500 may be combined together within the same package , if storage areas are capable of being distinguished from one another . additionally , a recording medium driver 650 writes the data such as the jbig program 201 a , the probability estimation table memory 202 in the rom 200 and the learning table memory 300 or the like to a package media such as a floppy disk or the like . the cpu 100 operates in conformity with the jbig program , which is stored in the rom 200 . the cpu 100 includes a register 101 for holding image data , which is read out from every block in an encoding target line , a register 102 for holding image data read out from every block in a line preceding the encoding target line by one line , a register 103 for holding image data read out from every block in a line preceding the encoding target line by two lines , a register 104 for holding a prediction result , a register 105 for holding a predicted value and a status value , which are read out from the learning table memory 300 and a register 106 for holding a range width for prediction - miss , which is read out from the probability estimation table memory 202 . here , a block mean a unit for reading out , for example , sixteen pixels or eight pixels as one block from each line in the image data memory 400 . furthermore , the cpu 100 has a register 107 for holding the contents of a context and a register 108 for holding flags indicating a result of investigating whether all the pixel in the encoding target line are white or not , a result of investigating whether all the pixels in the line preceding the encoding target line by one line are white or not and a result of investigating whether all the pixels in the line preceding the encoding target line by two lines are white or not . in response to the jbig program 201 a , the data , which are necessary for each register , are stored . the cpu 100 realizes the first embodiment of the present invention by executing the jbig program 201 a in conformity with the jbig system as will be explained later . an example in which the rom 200 stores the jbig program 201 a and the probability estimation table memory 202 fixedly was explained . however , in the case of altering this program , a memory such as a flash memory and an eeprom or the like may be used . alternatively , the jbig program , which is read from an outer recording medium , may be stored in a dram or an sram . the learning table , which is written in the ram 300 , stores a learning result as a table status while the cpu 100 repeatedly executes the jbig program . the fifo memory 500 stores encoded data , which have been generated by the cpu 100 from image data stored in the image data memory 400 . additionally , the recording medium driver 650 drives a recording medium to install contents of the jbig program 201 a to rom 200 or the like . the recording medium driver 650 also drives a recording media , which stores , for example , the jbig program 201 a and the contents of the table of the probability estimation table memory 202 and the content of the learning table of the learning table memory 300 . the jbig system encoding processing apparatus 700 includes the cpu 100 , the rom 200 , the ram 300 , the ram 400 , the ram 500 and the recording medium driver 650 , and it performs compression encoding processing in conformity with the jbig system . an image memory 800 comprises a recording medium for inputting the image data from a scanner , a digital camera and an optical converting apparatus or the like to record the image data temporarily . a transmission system 900 outputs the encoded image data supplied from the jbig system encoding processing apparatus 700 to a receiving side such as a facsimile and a personal computer through a transmission line . next , a procedure of the jbig program 201 a in conformity with the jbig system according to the first embodiment will be explained with reference to flowcharts shown in fig8 through fig1 . first , the whole operation will be explained with reference to fig8 . at the beginning of the encoding processing for one page , three all - white - line flags , i . e ., the first all - white - line flag pix for the encoding target line , the second all - white - line flag h 1 for the line preceding the encoding target line by one line , and the third all - white - line flag for the line preceding the encoding target line by two lines , are set ( step s 20 ). step s 20 is performed to assume that there are a line preceding the first line of the image by one line and a line preceding the first line by two lines to cope with a case of encoding the first line . next , it is determined whether or not to perform a typical prediction in which the encoding target line pix is compared with the line h 1 , which is preceding the encoding target line by one line ( step s 21 ). if the typical prediction should not be performed , one line investigation process is performed in which it is investigated whether or not all the pixels in the target line are white ( step s 22 ). if all the pixels in the target line are white , the all - white - line flag pix is set , otherwise the all - white - line flag pix is reset . next , it is determined whether or not all the three all - white - flags pix , h 1 , and h 2 are set ( step s 23 ). if all the three all - white - flags are set , that is , all the pixels in a region composed of the target line , the line preceding the target line by one line , and the line preceding the target line by two lines are white , it is determined whether or not the predicted value based on the context of which all the pixels are white is white ( step s 24 ). if the predicted value is white , a second single - line encoding process provided for a case where all the pixels in the region concerned is white is performed ( step s 25 ). if the result of determination at step s 23 is negative , that is , at least one pixel in the region composed of the target line , the line preceding the target line by one line , and the line preceding the target line by two lines is not white , a first single - line encoding process provided for a case where at least one pixel in the region concerned is not white is performed ( step s 26 ). if the result of determination at step s 23 is positive but the result of determination at step s 24 is negative , the first single - line encoding process provided for the case where at least one pixel in the region concerned is not white is performed ( step s 26 ). after performing step s 25 or s 26 , it is determined whether or not all the lines in the manuscript are processed ( step s 27 ). if the result of determination at step s 27 is negative , the flow returns to step s 22 . otherwise , the operation is terminated . if the result of determination at step s 21 is positive , that is there is a typical prediction , the target line is compared with the line preceding the target line by one line ( step s 29 ). then , it is determined whether or not the target line is the same as the line preceding the target line by one line ( step s 210 ). if they are not the same , the first single - line encoding process is performed ( step s 26 ). if they are the same the step s 26 is skipped . after performing or skipping the step s 26 , it is determined whether or not all the lines in the manuscript are processed ( step s 27 ). if the result of determination at step s 27 is negative , the flow returns to step s 29 . otherwise , the operation is terminated . the first single - line encoding process ( step s 26 ) was explained with reference to fig3 and explanation thereof is omitted here . the first single - pixel encoding process ( step s 95 ) in the first single - line encoding process ( step s 26 ) was also explained with reference to fig4 and the explanation thereof is omitted here . next , the detail of step s 22 will be explained with reference to fig9 a . referring to fig9 a , the all - white - line flags are shifted from line to line , that is , the all - white - line flag h 1 is substituted to the all - white - line flag h 2 , and the all - white - line flag pix is substituted to the all - white - line flag h 1 ( step s 32 ). next , the top address of the target line in the image data memory 400 is loaded to the address pointer ( not shown ) of the cpu 100 ( step s 33 ). image data are read from the address loaded to the address pointer , and are loaded to the register 101 ( step s 34 ). here , in the prior art , it was not possible load the image data to the register 101 fully across the whole register width . on the other hand , according to the present invention , because it is not needed to form a context , it is possible to store the image data to the register fully across the whole register width , whereby the number of loading operations is decreased . next , it is determined whether or not all the pixels in the read image data are white ( step s 35 ). if the result of determination at step s 35 is positive , the address in the address pointer is updated to the top address of the following pixels in the target line ( step s 36 ). that is , the address in the address pointer is increased by the width of the register 101 . next , it is determined whether or not all the pixels in the target line have been examined ( step s 37 ). if the result of determination at step s 37 is negative , the flow returns to step s 34 . otherwise , the all - white - flag pix for the target line is set ( step s 38 ). if the result of determination at step s 35 is negative , the all - white - flag pix for the target line is reset ( step s 39 ). next , the detail of step s 25 will be explained with reference to fig9 b . referring to fig9 b , in the second single - line encoding process , a second single - pixel encoding process ( step s 30 ), instead of the first single - pixel encoding process ( step s 95 ), for pixels in the target line is repeated until all the pixels in the target line are encoded ( step s 31 ). here , the steps s 90 , s 91 , s 92 , s 93 , s 94 , and s 96 in fig3 are omitted as compared with the first single - line encoding process . the reason why such omission is possible is that if all the pixels in the three lines are white , a unique template ( or context ) of which all the pixels are white ( i . e ., zero ) is applied to all the pixels in the target line , and it is not necessary to change a template ( or context ) every encoding target pixel . next , the detail of the second single - pixel encoding process ( step s 30 ) will be explained with reference to fig1 as follows : at first , the predicted value and the status value which correspond to the index which is formed of a context ( 0 ) are read from the learning table 300 ( step s 40 ). here , context ( 0 ) represents the context of which all the pixels are white . then , using the status value as an index , the range width for prediction - miss is read from the probability estimation table memory 202 , together with the status value when the prediction is successful ( step s 41 ). furthermore , by deducting the range width for prediction - miss from the range width showing probability that combination of white and black appears , the latter range width is updated ( step s 42 ). here , the probability estimation table memory 202 conforms with the standard of the jbig encoding system ( recommendation t . 82 ) and explained before with reference to fig6 . here , in the first single - pixel encoding process ( step s 95 ) in the first single - line encoding process ( step s 26 ), the process of determining whether the actual value of encoding target pixel is identical with the predicted value or not ( step s 110 ) is necessary . on the other hand , in the second single - pixel encoding process ( step s 30 ) in the second single - line encoding process ( step s 25 ), the process of determining whether the actual value of encoding target pixel is identical with the predicted value or not ( step s 110 ) is not necessary . next , it is determined whether the normalization process is required to be performed or not ( step s 43 ). if the determination result at step s 43 is affirmative , a prediction - hit process is performed ( step s 44 ) and then , the normalization process is performed ( step s 45 ). if the determination result at step s 43 is negative , the step s 44 and s 45 are skipped . step s 44 and step s 45 were explained and the explanations thereof are omitted here . after performing or skipping steps s 44 and s 45 , it is determined whether or not the block has been terminated ( step s 46 ). if the block has not been terminated , the encoding processing returns to the processing for renewing the range width ( step s 42 ). this is because the predicted value , the status value and the range width for prediction - miss are not changed , and are not needed to be read out . it is obvious that the present invention is especially effective for the image mainly composed of white pixels , such as a document image , which is frequently treated by a facsimile or the like . this jbig encoded image data is transmitted to a facsimile in receiver side via the transmission system 900 . copying the above program in the jbig system to the recording medium , which is inserted in the recording medium driver 650 , it may be possible to output this copied program as a recording package . further , it may be possible to use the present recording package as an application in the jbig system by other personal computer . in the above embodiment , a case where a model template is composed of three lines was explained . however , the present invention is not limited to such model template , but may be generalized to cope with a case where a model template is composed pixels in two lines , a case where a model template is composed pixels in four lines , a case where a model template is composed pixels in several lines , and a case where a model template is composed pixels in a number of lines .