Abstract: An optical reader of a form is discussed where the form has a stored known boundary or boundaries. When the boundaries in a captured image do not match those of the stored known boundaries, it may be determined that an obstruction exists that will interfere with a correct reading of the form. The boundary may be printed, blank, and may include quiet areas, or combinations thereof in stored known patterns. A captured image of the form is compared to retrieved, stored boundary information and differences are noted. The differences may be thresholded to determine if an obstruction exists. If an obstruction is detected, the operator may be signaled, and the location may be displayed or highlighted. The form may be discarded or obstruction may be cleared and the form may be re-processed.

Abstract: A system and process for reading forms using a curvature distortion correction scheme is disclosed. A model image of a known form is partitioned into sectors defined by at least three alignment marks, and a transfer or correction function for each sector is generated by comparing the locations of alignment marks on a captured unread image of a form to those on a model image. The transfer function is then applied to the other marks within the sector to calculate a correct location of the marks. Each sector is sized to reasonably ensure curvature distortions are handled such that all the marks on a form are properly found and interpreted. Errors may be checked and, if they persist, smaller sectors may be defined and employed, if available.

Abstract: An optical reader of a form is discussed where the form has a stored known boundary or boundaries. When the boundaries in a captured image do not match those of the stored known boundaries, it may be determined that an obstruction exists that will interfere with a correct reading of the form. The boundary may be printed, blank, and may include quiet areas, or combinations thereof in stored known patterns. A captured image of the form is compared to retrieved, stored boundary information and differences are noted. The differences may be thresholded to determine if an obstruction exists. If an obstruction is detected, the operator may be signaled, and the location may be displayed or highlighted. The form may be discarded or obstruction may be cleared and the form may be re-processed.

Abstract: A system and process for reading forms using a curvature distortion correction scheme is disclosed. A model image of a known form is partitioned into sectors defined by at least three alignment marks, and a transfer or correction function for each sector is generated by comparing the locations of alignment marks on a captured unread image of a form to those on a model image. The transfer function is then applied to the other marks within the sector to calculate a correct location of the marks. Each sector is sized to reasonably ensure curvature distortions are handled such that all the marks on a form are properly found and interpreted. Errors may be checked and, if they persist, smaller sectors may be defined and employed, if available.