Lightbrush can process images in many common formats, including most camera raw images:
- Camera raw images (e.g. uncompressed CR2 or NEF files) will provide the best results since they contain the maximum amount of unmodified information from the camera’s sensor. HDR files are fine as well.
- Linear 16-bit TIFF or EXR images derived directly from a camera raw image are reasonable alternatives. Make sure there are no saturation enhancements or color adjustments aside from white balancing.
- Standard camera JPEG format may work with these iamges, but since the colors and intensities do not obey correct physical relationships, the quality of the results are degraded.
In linear data, image values are proportional to the number of photons arriving at the sensor in the camera. For instance, if a value of 0.4 means the sensor counts 1,000,000 photons, then a value of 0.8 would mean the sensor counted 2,000,000 photons. Lightbrush, as a physics-based system, operates in a linear space.
In gamma-corrected data, linear values are transformed by a gamma curve similar to output = input2.2. Dark areas are brightened, revealing details, and the contrast in bright areas is decreased. Nearly all images displayed on computers and smartphones are in a gamma-corrected space.
Images with gamma compression or color enhancement do not accurately measure the light captured by the camera sensor and will produce lower quality results. Therefore, we recommend making Lightbrush the first step in your workflow, starting with the camera raw image.