1 Correction to: International Journal on Document Analysis and Recognition (IJDAR) https://doi.org/10.1007/s10032-021-00386-0

The original article was published with incorrect Eq. 4. The correct equation is

$$ L^{*{\prime }} = 100\,{_{0}} \left\lfloor {{1 - \left( {_{0} \left\lfloor {100 - L^{*} } \right\rceil^{1} + {}_{0} \left\lfloor {V + S - 1} \right\rceil^{1} } \right)} \mathord{\left/ {\vphantom {{1 - \left( {_{0} \left\lfloor {100 - L^{*} } \right\rceil^{1} +\,_{0} \left\lfloor {V + S - 1} \right\rceil^{1} } \right)} 2}} \right. \kern-\nulldelimiterspace} 2} \right\rfloor^{1} , $$
(4)

The original article has been updated.