Batch Editing

color calibration

Batch Editing

A fully-featured color-space correction, white balance adjustment and channel mixer module.

This simple yet powerful module can be used in the following ways:

  • To adjust the white balance (chromatic adaptation), working in tandem with the white balance module. Here, the white balance module makes some initial adjustments (required for the demosaic module to work effectively), and the color calibration module then calculates a more perceptually-accurate white balance after the input color profile has been applied.

exposure

Batch Editing

Increase or decrease the overall brightness of an image.

This module has two modes of operation:

manual
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. Ansel 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.

module controls

mode
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). To adjust by more than the default limits shown on the slider, right click and enter the desired value up to +/-18 EV (see module controls).
The color picker tool on the right sets the exposure such that the average of the selected region matches the target lightness defined in spot exposure mapping options.
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.

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