Acutance is a measure of the perceived sharpness of an image, describing how quickly tonal transitions from dark to light are reproduced on film or digital sensors. In high-contrast subjects, a film or developer with high acutance produces a steeper transition between densities, making edges appear more defined and the image visually sharper. Acutance is influenced by factors such as film type, developer formulation, lens quality, and image processing techniques. Photographers use acutance to enhance image detail, improve the perception of sharpness, and achieve professional-quality results in portrait, landscape, and fine art photography.