What major change in enhanced definition TV (EDTV) improves picture quality over standard definition TV (SDTV)?

The major change in enhanced definition TV (EDTV) that improves picture quality over standard definition TV (SDTV) is progressive scanning mode. In a progressive scanning system, each frame is drawn sequentially, which means that all the lines of the picture are displayed in one pass. This results in a smoother and clearer image, particularly during fast motion scenes, as it reduces the chances of motion blur and artifacts that can occur with interlaced scanning.

In contrast, standard definition TV typically uses interlaced scanning, where the display alternates between two fields of lines (odd and even), which can lead to jagged edges and less detail in moving images. Progressive scanning effectively doubles the perceived frame rate because it shows all lines simultaneously, leading to improved overall sharpness and detail. This is especially noticeable in larger screens or when viewing HD content.

While higher pixel resolution, increased frame rate, and interlaced scanning can contribute to image quality, the key enhancement that distinguishes EDTV from SDTV in terms of how images are rendered is the adoption of progressive scanning. This technique fundamentally changes how the image is displayed, leading to the enhanced viewing experience that EDTV offers.