HDRMerge是开源的raw图像合并工具，它既提供了命令行接口也提供了GUI界面（支持Linux和Windows系统，macOS版本正在开发中）。
网站：http://jcelaya.github.io/hdrmerge/
HDRMerge combines two or more raw images into a single raw with an extended dynamic range. It can import any raw image supported by LibRaw, and outputs a DNG 1.4 image with floating point data. The output raw is built from the less noisy pixels of the input, so that shadows maintain as much detail as possible. This tool also offers a GUI to remove ‘ghosts’ from the resulting image.
HDR图片合成技术，是日本索尼公司图片处理算法。原理是放置两张曝光图片：一张暗和一张亮。经过合成处理生成一张更加接近现实美观的图片。
HDRMerge源代码：https://github.com/jcelaya/hdrmerge
另一个类似的工具：https://github.com/wjakob/hdrmerge
Ubuntu安装HDRMerge：
$ sudo add-apt-repository ppa:dhor/myway
$ sudo apt-get update
$ sudo apt-get install hdrmerge
查看帮助：
$ hdrmerge --help
Usage: HDRMerge [--help] [OPTIONS ...] [RAW_FILES ...]
Merges RAW_FILES into an HDR DNG raw image.
If neither -a nor -o, nor --batch options are given, the GUI will be presented.
If similar options are specified, only the last one prevails.
Options:
--help Shows this message.
-o OUT_FILE Sets OUT_FILE as the output file name.
The following parameters are accepted, most useful in batch mode:
- %if[n]: Replaced by the base file name of image n. Image file names are first sorted in lexicographical order. Besides, n = -1 is the last image, n = -2 is the previous to the last image, and so on.
- %iF[n]: Replaced by the base file name of image n without the extension.
- %id[n]: Replaced by the directory name of image n.
- %in[n]: Replaced by the numerical suffix of image n, if it exists.
For instance, in IMG_1234.CR2, the numerical suffix would be 1234.
- %%: Replaced by a single %.
-a Calculates the output file name as %id[-1]/%iF[0]-%in[-1].dng.
-B|--batch Batch mode: Input images are automatically grouped into bracketed sets,by comparing the creation time. Implies -a if no output file name is given.
-g gap Batch gap, maximum difference in seconds between two images of the same set.
--single Include single images in batch mode (the default is to skip them.)
-b BPS Bits per sample, can be 16, 24 or 32.
--no-align Do not auto-align source images.
--no-crop Do not crop the output image to the optimum size.
-m MASK_FILE Saves the mask to MASK_FILE as a PNG image. Besides the parameters accepted by -o, it also accepts:
- %of: Replaced by the base file name of the output file.
- %od: Replaced by the directory name of the output file.
-r radius Mask blur radius, to soften transitions between images. Default is 3 pixels.
-p size Preview size. Can be full, half or none.
-v Verbose mode.
-vv Debug mode.
RAW_FILES The input raw files.
