PhotoMill is intended for various operations involving images. It is actually a three-in-one application that combines an image converter, a metadata editor and a photo browser. Although it has a nice dark interface, I sometimes found it hard to navigate through its functions. Luckily, the product is accompanied with an excellent tutorial and you can even download a manual.
You should begin by adding the desired picture folders, which can be done by browsing for them in Finder or via drag-and-drop operations. The image browser has three different panels. One of them displays detailed information about the selected photograph. The second allows splitting images into groups, which responds to such criteria as a date, size and format. Moreover, you can create new group presets by using combinations of other criteria. The third panel is intended for searching and can be toggled on and off.
One of the advantages of the tool is that it allows converting batches of pictures to another format. In this regard, it supports BMP, GIF, HEIC, JPEG, PDF, PNG and TIFF. In addition to format conversion, it also allows other batch operations, including watermarking, scaling, correcting contrast automatically and adding keywords. In all cases, the tool supports live previewing the changes before the actual conversion.
It is good that PhotoMill can change your pictures’ metadata. Thus, by editing EXIF properties, it is possible to change the capture date, remove private tags, set a different GPS location, add keywords and provide ratings. Picture files can also be renamed and, luckily, you can use patterns to construct names.
In addition, the application lets you perform other operations, such as scaling, cropping, changing resolution, adding borders, trimming a given color, rotating and flipping. Likewise, it supports applying convert filters to change contrast, white balance, exposure, temperature and sharpness. Other more specific tools can add transparency by blending a source image and a grayscale mask, replace the chosen color with transparency or, reversely, replace transparency with a given color.
All in all, PhotoMill lets you modify and convert batches of pictures. I recommend this tool; yet, I would like to see its workflow improved. The product is free to try without any limitations, an opportunity you would probably like to take.