RawTherapee is a cross-platform raw image processing program. Rather than being a raster graphics editor such as Photoshop or GIMP or a digital asset management program like digiKam, it is specifically aimed at raw photo post-production. And it does it very well - at a minimum, RawTherapee is one of the most powerful raw processing programs available.
DarkTable is an open source photography workflow application and raw developer. A virtual light table and darkroom for photographers. It manages your digital negatives in a database, lets you view them through a zoomable light table and enables you to develop raw images and enhance them.
digiKam is an advanced open-source digital photo management application that runs on Linux, Windows, and MacOS. The application provides a comprehensive set of tools for importing, managing, editing, and sharing photos and raw files.
You can use digiKam's import capabilities to easily transfer photos, raw files, and videos directly from your camera and external storage devices (SD cards, USB disks, etc.). The application allows you to configure import settings and rules that process and organize imported items on-the-fly.
digiKam organizes photos, raw files, and videos into albums. But the application also features powerful tagging tools that allow you to assign tags, ratings, and labels to photos and raw files. You can then use filtering functionality to quickly find items that match specific criteria.
The application provides a comprehensive set of editing tools. This includes basic tools for adjusting colours, cropping, and sharpening as well as advanced tools for, curves adjustment, panorama stitching, and much more. A special tool based on lensfun library permit to apply lens corrections automatically on images.
LightZone is professional-level digital darkroom software for Windows, Mac OS X, and Linux, that includes RAW processing and editing. Rather than using layers in the way that other photo editors do, LightZone lets the user build up a stack of tools which can be rearranged, readjusted, turned off and on, and removed from the stack. It's a completely non-destructive editor, where any of the tools can be re-adjusted or modified later - even in a different editing session. A tool stack can even be copied to a batch of photos at one time.
Photivo is a free and open source photo processor which handles RAW files as well as raster photos. Photivo tries to provide the best algorithms available; even if this implies some redundancy. It offers the most flexible and powerful denoise, sharpen and local contrast (fake HDR) algorithms in the open source world.
Photivo is intended to be used in a workflow together with digiKam/F-Spot/Shotwell and Gimp. It needs a quite strong computer and is not aimed at beginners.
Rawstudio is an open-source program to read and manipulate RAW images from digital cameras. The main focus of Rawstudio is to enable efficient review and fast processing of large image collections.
Rawstudio is intended as the first tool in your image processing chain. After you have made your overall image adjustments to your image, you can use an image editing application to further work on your images. Rawstudio itself is a highly specialized application for reviewing and processing RAW images, not a fully featured image editing application.
Luminance HDR is an open source graphical user interface application that aims to provide a workflow for HDR imaging.
Rapid Photo Downloader
Website: Rapid Photo Downloader
Improve your photographic workflow with Rapid Photo Downloader for Linux, which is written by a photographer for professional and amateur photographers. Its goal is to be the best photo and video downloader for the Linux Desktop.
Rapid Photo Downloader downloads from every camera supported by gphoto2, including smartphones. It downloads in parallel from multiple devices, as well as directly from your computer.
Unique to Rapid Photo Downloader is its Timeline, which groups photos and videos based on how much time elapsed between consecutive shots. Use it to identify photos and videos taken at different periods in a single day or over consecutive days.
Shotwell is an image organizer designed to provide personal photo management for Linux desktop environments. It replaces the popular F-Spot as the standard image tool for several GNOME-based Linux distributions, including Fedora and Ubuntu.
Shotwell can import photos and videos from a digital camera directly and automatically groups photos and videos by date, and supports tagging. Its image editing features allow users to straighten, crop, eliminate red-eye, and adjust levels and colour balance. It also features an auto "enhance" option that will attempt to guess appropriate levels for the image.
While not strictly a Lightroom alternative, Hugin is still a useful tool if you are creating panoramas. With Hugin you can assemble a mosaic of photographs into a complete immersive panorama, stitch any series of overlapping pictures and much more.