An image processing apparatus that distinguishes between alphanumeric symbols on a white background and those on a mesh pattern and performs individual image data processing includes an analog-to-digital converter for converting analog data to digital data, a first determiner for determining a region as a white picture element region when the region is composed of a predetermined white picture element and a plurality of white picture elements surrounding the predetermined white picture element in the digital data, a conditional variant setter for setting a conditional variant to white picture elements in the white picture element region, a potential thin line extractor for extracting a potential thin line pattern using a black picture element that has been corrected after being extracted from the digital data and a white picture element that has been corrected after being extracted from the digital data, and a second determiner for determining which one of an alphanumeric symbol on a white background, an alphanumeric symbol on a mesh pattern, and a design pattern is similar to the potential thin line pattern based on the conditional variant and the potential thin line pattern extracted by the potential thin line extractor, and for renewing the conditional variant based on a determination result of the second determiner.