LightZone is a "digital darkroom" for your JPEG and RAW images. It's been around for years and was once a commercial product, but is now open source.
Getting started can be as easy as opening an image and choosing a "Style", a built-in combination of editing settings. Examples are "Soft Skin Tones", "SLR Sharpen", "Midtones Sharpening", "Skin Glow", "Bright Scene", "Dark Scene", "Fill Flash", "Crisp", "Hard", and "Soft Toning".
There are also multiple tools available which allow you to take more control, including "Relight", "Sharpen", "Gaussian Blur", "Hue/ Saturation", "Color Balance", "White Balance", "Black and White", "Noise Reduction", "Clone", "Spot" and "Red Eyes".
Most of these give you plenty of scope for fine-tuning. Click "Sharpen", say, and you're able to set an amount, radius, threshold, blending mode, opacity, make a colour selection, and more.
LightZone's "regions" are vector masks which restrict a tool's effect to specific areas of an image.
Whatever tools you use are organised in a "stack", similar to layers in other applications. This means that if you carry out several operations on an image, you can always step back to any of these, modify or delete it, and view the results right away.
What's new in 4.1.8 (see changelog for more)?
- Add Spanish Help files by RobertoQ
- Show GPS metadata from EXIF on Metadata pane. Clicking the GPS metadata will open Google Maps in a web browser.
- Show more makernote metadata, especially lens names
- Support more Crop ratios (#199)
- Accept multiple files and folders as command line arguments or drag-and-drop onto LightZone icon
- Open recent file/folder in another frame when in Editor mode
- To release unused JVM memory, introduce G1 Garbage Collector. Both MinHeapFreeRatio and MaxHeapFreeRatio are set to 30.
- Do not show stack trace from BadImageMetadataException
- Append "_lzn" suffix for batch-processed images
- Windows - Support build on MSYS2
It's not quite Lightroom, but LightZone does have plenty of photo-tweaking technology, and is very usable even if you have no detailed photo editing experience at all.