Compare letters from images for recognition (opencv, java) -

i have been working project lately in order detect letters , im little bit stuck right now.

so far have been able extract letters , crop them , save them new images. compare letters recognition. lets have saved letters using reference or template in order detect match between letters.

how can result compare example letter letters Å,Ä,a , tell match?

letter a

letter Ä

letter Å

i have tried matchtemplate not understand it. dont know how continue..

     mat img = highgui.imread("image.jpg");      mat templ = highgui.imread("aaa.jpg");                        int result_cols = img.cols() - templ.cols() + 1;      int result_rows = img.rows() - templ.rows() + 1;      mat result = new mat(result_rows, result_cols, cvtype.cv_32fc1);       imgproc.matchtemplate(img, templ, result, 1); 

i of course use tesseract, recognize letters in opencv letters same , not change font or that. there no need ocr engine.