How much handwritten text is needed for text-independent writer verification and identification

The performance of off-line text-independent writer verification and identification increases when the documents contain more text. This relation was examined by repeatedly conducting writer verification and identification performance tests while gradually increasing the amount of text on the pages. The experiment was performed on the datasets Firemaker and IAM using four different features. It was also determined what the influence of an unequal amount of text in the documents is. For the best features, it appears that the minimum amount of needed text is about 100 characters.