Described herein is a level I (overt) feature for security printing intended to deter unauthorized modification of text documents. The exemplary method includes generating a textured background that follows the contour of the text it surrounds and is difficult to modify. The background patterns may be generated with a two-step procedure that first creates a smooth function and then modulates it to produce patterns with sharp contrast. Tampering will be deterred as visible artifacts will be created when text is altered. Compared to the levels II and III features, the exemplary method relies on human vision for detection and does not require any special tools and instruments. It can be used in applications where fast, simple and inexpensive inspection is essential, or combined with other technologies for enhancing overall effectiveness.