A composition comprising a mixture, having a maximum molar ratio of acid to base of 0. The method and apparatus further calculate a correlation value between the error signal and the decision signal, and accumulate the correlation value to produce the accumulated value, thereby adaptively compensating for an inaccuracy in the AD converter. A color mixture correcting section is configured to correct a color mixture component contained in the mixed saturation signal read out of the holding section. The extracted information may include text strings and text characteristics of the text strings. At least one of the new code and the coherence code is executed. An optimal offset is determined based on the collected values and the corresponding tracking positions.