2. The character string recognition apparatus according to claim 1 ; wherein the means for determining the number of character string lines creates a frequency distribution on the number of first segments showing a predetermined number of character string lines according to data of the number of character string lines in each of the first segments, and determines the number of character string lines in the character string search area as a whole, with the number of character string lines having a maximum frequency.
2. The character string recognition apparatus according to claim 1 ; wherein the means for determining the number of character string lines creates a frequency distribution on the number of first segments showing a predetermined number of character string lines according to data of the number of character string lines in each of the first segments, and determines the number of character string lines in the character string search area as a whole, with the number of character string lines having a maximum frequency. 4. The character string recognition apparatus according to claim 2 ; wherein the means for preparing segments increases or decreases the number of segments for the character string search area to make up a second type of segments, being different from the first segments, if the frequency distribution on the number of first segments showing the predetermined number of character string lines is not normal.