HDRMerge vs ON1 HDR

HDRMerge combines exposure-bracketed raw files, or bracketed frames within one raw file, to create raw images with extended dynamic range. It outputs DNG 1.4 images with floating-point data, drawing on less noisy input pixels to retain shadow detail. In its graphical interface, users can adjust the merge mask to address ghosts from objects that moved between exposures. The command-line interface supports batch processing of raw image sets. HDRMerge can align small translations and crop the output to the area shared by the inputs. Input images must match in size, orientation, Bayer pattern, and black and white levels; the manual says this usually means using images made with the same camera. Tone mapping can happen later in another program that supports high-dynamic-range raw DNG images. The maker identifies RawTherapee, darktable, and recent Adobe products as supporting the floating-point DNG output. HDRMerge is free software under the GNU General Public License, version 3 or later, and runs on Linux, macOS, and Windows. The maker describes it as a way to bring merged HDR images into a standard raw development workflow.

ON1 HDR has no write-up on Specifiction yet; its figures are above.