Stamp Detection in Color Document Images

An automatic system for stamp segmentation and further verification is needed especially for environments like insurance companies where a huge volume of documents is processed daily. However, detection of a general stamp is not a trivial task as it can have different shapes and colors and, moreover, it can be imprinted with a variable quality and rotation. Previous methods were restricted to detection of stamps of particular shapes or colors. The method presented in the paper includes segmentation of the image by color clustering and subsequent classification of candidate solutions by geometrical and color-related features. The approach allows for differentiation of stamps from other color objects in the document such as logos or texts. For the purpose of evaluation, a data set of 400 document images has been collected, annotated and made public. With the proposed method, recall of 83% and precision of 84% have been achieved.