The Constrained Run-Length Algorithm (CRLA) is a well-known technique for page segmentation which is also known as the Run-Length Smoothing/Smearing Algorithm (RLSA). This is a very well known technique for segmenting a document image into homogeneous regions. The algorithm is very efficient for partitioning documents with
The previous two posts briefly describe the Constrained Run-Length Algorithm (CRLA) or Run Length Smoothing Algorithm (RLSA) and its related issue.
 Hung-Ming Sun, 2006, "Enhanced Constrained Run-Length Algorithm for Complex Layout Document Processing", International Journal of Applied Science and Engineering 2006.4, 3: 297-309