An approach to estimation of text recognition algorithm parameters (character templates) is proposed, based upon the learning sample that consists of samples of text line images and corresponding character sequences and doesn't require segmentations of these images into images of separate characters. Also a method is proposed for template size estimation along with the estimation of its value. Formulation of the general learning problem in such a way allows us to simplify the process of template estimation for a given text image source significantly by removing the need to estimate manually template sizes and mark character regions on each image, and leaving only the need to type in the text that corresponds to learning images from the sample.