Raw Therapee is an open source image processing tool which provides a huge range of ways to enhance your digital photos and other images. (As the name suggests, it's intended for use with raw files from digital cameras, but the program can also import JPEG, TIFF and PNG files.)
The vast array of high-end novices will quickly confuse the image processing novice, but if you know what you're doing then there's a great deal to explore here.
RAW image quality may be enhanced by a good range of demosaicing algorithms, for instance: AMaZE, DCB, fast, AHD, EAHD, HPHD & VNG4.
Colour handling controls cover everything from simple channel mixing and RGB curves, to white balance, HSV, vibrance and more.
Would you like to enhance details? The Detail pane contains no less than seven options: Sharpening, Edges, Microcontrast, Impulse Noise Reduction, Noise Reduction, Defringe and Contrast by detail levels. And each of these is highly configurable, so for example select Sharpening and you can choose the algorithm (Unsharp Mask or RL Deconvolution), radius, amount, threshold and more.
And you also get great exposure controls, a stack of powerful lens/ geometry correction tools, EXIF/ IPTC metadata editing, batch processing, command line control, lots of configuration options, and the list goes on.
Beginners should look elsewhere, then, but if you're familiar with this kind of high-end image processing tool then you'll get a lot out of Raw Therapee. Its interface is occasionally clunky and performance isn't always as good as the authors appear to think, but there's an enormous array of processing power on offer and it's a great way to get the very most from your digital images.
V5. New Features
Monitor profile and rendering intent support.
Print soft-proofing support.
Automatic chroma noise reduction, manual luminance noise reduction using sliders and curves.
The "Inspect" tab in the File Browser lets you see a 100% preview of the image whose thumbnail your mouse cursor hovers over, which is either the largest JPEG image embedded in the raw file or the image itself when hovering over non-raw images.
The curve pipette allows you to pick the right point of a curve by clicking in the preview, and input/output values so that you can set the desired output value for a given input value.
Post-resize sharpening, to give your photos that subtle crispness after resizing them.
Dual-illuminant DCP support with curves, base tables, look tables and baseline exposure.
New exposure tone curve modes "Luminance" and "Perceptual".
Queue processing will stop if an error is encountered while saving, e.g. if you run out of disk space.
The Contrast by Detail Levels tool received the "Process Locate Before/After Black-and-White" option.
Rec. 2020 ICC profile added.
The Navigator can show RGB, HSV and L*a*b* values in a range of 0-255, 0-1 or %.
The Lockable Color Picker allows you to place multiple sample points over the preview to measure colors and see them change in real time as you manipulate the image. They support the same ranges as the Navigator.
Grayscale JPEG and TIFF images are now supported.
32-bit TIFF files are supported.
In addition to these new features, RawTherapee received over two years worth of amazing speedups, code cleanups and bug fixes, making it faster and more stable than ever before!
Powerful, professional and packed with high-end image processing features, Raw Therapee offers a host of ways to enhance and adjust your digital images.