Depth of field (DoF) fusion is a digital image processing technique designed to expand the sharp depth range of an image. In optical imaging, constrained by the lens’s inherent depth of field, a single frame rarely renders both foreground and background in full sharpness. DoF fusion captures a sequence of shots focused at different distances across the same scene. Algorithms then extract the sharpest segments from each frame and merge them together, outputting one high-quality image with crisp detail spanning the entire depth from near foreground to far background.

Its core workflow generally consists of three steps: image alignment, sharpness evaluation, and pixel-level fusion. First, the multi-focus image sequence undergoes precise registration to eliminate tiny positional shifts introduced during shooting. Next, local sharpness metrics (such as gradient magnitude and frequency-domain energy) are calculated to select the sharpest source pixel for every coordinate position. Finally, weighted blending or optimal region compositing generates a fully focused final image.

This technology sees widespread adoption in macro microscopy, industrial inspection and general macro photography. It effectively breaks the physical limitations of optical depth of field, supplying digital data with more complete fine details and richer information for subsequent image analysis workflows.