12. An image processing method to enable a computer to perform a process for document registration processing, the process comprising: inputting document data of a document; identifying a position of a string in the document; identifying a mark handwritten from a highlighter and is non-textual, the mark being separate from the string, given in the document; and detecting an orientation of the mark, wherein the mark is defined by a range from a start position and an end position based on the detected orientation, and extracting a new character string based on the position of the identified string and the identified mark, and the mark identified and defined based on the detected orientation.
12. An image processing method to enable a computer to perform a process for document registration processing, the process comprising: inputting document data of a document; identifying a position of a string in the document; identifying a mark handwritten from a highlighter and is non-textual, the mark being separate from the string, given in the document; and detecting an orientation of the mark, wherein the mark is defined by a range from a start position and an end position based on the detected orientation, and extracting a new character string based on the position of the identified string and the identified mark, and the mark identified and defined based on the detected orientation. 13. The image processing method of claim 12 , further comprising: extracting the string based on the identified position and whether the string overlaps the identified mark.