Color thermal printer having high precision dye donor web positioning

A thermal printer includes a web transport for positioning a dye donor web along a path; a sensor along the path and spaced from the print line for detecting the arrival of a leading edge of a dye frame, and a control for the web transport. The control is adapted to reposition the dye donor web along the path so that the leading edge of the dye frame is in substantial alignment with the print line before printing the dye frame begins. The web transport moves the dye donor web in both forward and reverse directions past the print line, and the sensor detects the leading edge of a frame while the donor web moves in a forward direction. The control stops the web and reverses it to thereby rewind the dye donor web until the edge of the dye frame is in substantial alignment with the print line. The control adjusts the amount of repositioning of the dye donor web that is effected as a function of the detected leading edge's location along dye donor web.