Bruce recently went to the eye doctor because he couldn't see clearly enough to do the crossword puzzle in the newspaper. He could see well enough to drive, just not well enough to do the puzzle. His eye doctor said he had presbyopia, a condition that is common in people who are middle aged. The doctor said that Bruce could continue to do the crossword puzzle, but he would need to wear reading glasses. Clearly, a manufacturer of reading glasses would benefit from using a _____ segmentation approach.