Increase or decrease the overall brightness of an image.
This module has two modes of operation:
- Set the exposure, black level and clipping threshold manually
- automatic (RAW images only)
- Use an analysis of the image’s histogram to automatically set the exposure. Darktable automatically selects the exposure compensation that is required to shift the selected percentile to the selected target level (see definitions below). This mode is particularly useful for automatically altering a large number of images to have the same exposure. A typical use case of automatic mode is deflickering of time-lapse photographs.
- Choose the mode of operation (automatic/manual).
- compensate camera exposure (manual mode)
- Automatically remove the camera exposure bias (taken from the image’s Exif data).
- exposure (manual mode)
- Increase (move to the right) or decrease (move to the left) the exposure value (EV).
- clipping threshold (manual mode)
- Define what percentage of bright values are to be clipped in the calculation of the exposure and black level correction. Use the color picker to sample a portion of the image to be used for this calcuation.
- percentile (automatic mode)
- Define a location in the histogram to use for automatic exposure correction. A percentile of 50% denotes a position in the histogram where 50% of pixel values are above and 50% of pixel values are below that exposure.
- target level (automatic mode)
- Define the target level for automatic exposure correction (EV) relative to the white point of the camera.
- black level correction (manual and automatic modes)
- Adjust the black level point to unclip negative RGB values.
Note: Do not use the black level correction to add more density in blacks as this can clip near-black colors out of gamut by generating negative RGB values. This can cause problems with some modules later in the pixelpipe. Instead, use a tone mapping curve to add density to the blacks. For example, you can use the relative black exposure slider on the scene tab of the filmic rgb module, or establish a deeper toe in the base curve module.