The cost of display-referred is an early loss of the relationship between pixel luminosity and saturation (usually also involving hue shifts), which is responsible for the infamous “HDR look” when the dynamic range increases. A tone curve is automatically (and irreversably) applied to this data to make the image look “good” on your display and subsequent edits are carried out on top of this already highly-modified image data. In display-referred processing the data from your Raw file is initially compressed into a range that represents pure black as 0 and pure white as 1, fixing mid-gray at 0.5. This approach is used extensively in cinematography and is known to be much more robust than the traditional display-referred approach. If you have used other Raw software in the past (or darktable prior to version 3.0) you may notice some significant differences from what you are used to – darktable now uses a scene-referred approach for most of its processing modules. □scene-referred workflow: a new approach If the scene dynamic range is lower than that of your camera, you may wish to dial in some over-exposure (decrease shutter speed or increase aperture) to capture more light and reduce noise. As a general rule of thumb, in cases where the scene-dynamic-range exceeds that of your camera, it is safe to underexpose all images by 0.5 to 1 EV (by reducing the ISO sensitivity if possible) even if the in-camera preview looks darker than expected (the preview is not the raw data). Where possible, you are advised to use exposure to-the-right (ETTR) techniques to maximize the amount of data available for processing while avoiding clipping. Under- or over-exposure can be “fixed” by darktable to some extent but no software can recover information that is not present in the Raw image (clipped highlights). Good image processing techniques start in the camera – a well-exposed image (without blown highlights or heavily crushed blacks) will always make post-processing much more straightforward. □getting started □take a well-exposed photograph You are advised to follow the guidelines provided below, up to the end of the image processing in 3 modules section and then choose other areas to learn as-and-when you need to use those techniques in your images. This section is intended to get you comfortable processing images in the darkroom view using a scene-referred workflow.
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