Which of the following techniques would NOT be used for improving image sharpness?

Increasing film speed refers to the sensitivity of the film to radiation, allowing for quicker exposure times. While this can be beneficial for patient comfort and operational efficiency, it does not contribute to image sharpness. In fact, higher film speeds can sometimes lead to decreased resolution and clarity, as the inherent grain structure of faster films can produce a less defined image.

On the other hand, decreasing the source to film distance typically enhances image sharpness, as it reduces the amount of scatter radiation and minimizes image blurriness. Increasing the source to object distance also enhances sharpness by reducing distortion and improving resolution. Maintaining parallelism is essential for ensuring that the image accurately represents the object being radiographed, further contributing to sharpness. Therefore, the technique that does not aid in improving image sharpness is indeed increasing film speed.