While this module can provide a quick and convenient way to make simple adjustments to an image, it must be used with care. Normally exposure adjustments should come before input color profile in the pixelpipe, and color adjustments should come after. Because the basic adjustments module combines all of these functions into a single operation in the pixelpipe, it may not play nicely with other modules. Therefore, if you plan to use basic adjustments with other modules, please instead consider using the exposure + base curve / tone curve / filmic rgb + color balance modules so that these operations occur in the correct places in the pixelpipe.
- black level correction
- Equivalent to black level correction in the exposure module, this slider defines the threshold at which dark gray values are cut off to pure black. Reducing this can bring some dark colors back into gamut. Increasing this slider may appear to increase the contrast and pop of an image, but it can push dark colors out of gamut, and clipped data cannot be recovered further down the pixel pipe. To control the contrast in the shadows, it is better to use other modules such as tone curve or levels, which mitigate these negative impacts further down the pixel pipeline.
- Adjust exposure compensation. Adding 1 EV of exposure compensation is equivalent to doubling the exposure time in camera, opening the aperture by 1 stop, or doubling the ISO.
Positive exposure corrections will make the image brighter. As a side effect noise level is increased. Depending on the basic noise level of your camera and the ISO value of your image, positive exposure compensations with up to 1EV or 2EV should still give reasonable results.
Negative exposure corrections will make the image darker. Given the nature of digital images this can not correct for fully blown out highlights but allows you to reconstruct data if only some of the RGB channels are clipped (see the highlight reconstruction module for information on how to deal with clipped pixels).
- highlight compression
- Compress the highlights of the image in order to recover detail.
- Equivalent to the contrast slider in the color balance module, this is used to increase the separation of luminance values around a fulcrum point, in effect making the tone curve steeper. The middle grey slider sets the fulcrum point for the contrast, and any pixels whose luminance matches this middle grey point will be unaffected. Pixels brighter than the middle grey point will become even brighter, and pixels darker darker than the middle grey point will become even darker.
- preserve colors
- If a non-linear tone curve is applied to each of the RGB channels individually, then the amount of tone adjustment applied to each color channel may be different, and this can cause hue shifts. Therefore, the preserve colors menu provides different methods of calculating the “luminance level” of a pixel. The amount of tone adjustment is calculated based on this luminance value, and then this same adjustment is applied to all three of the RGB channels. Different luminance estimators can affect the contrast in different parts of the image, depending on the specific characteristics of that image. The user can therefore choose a particular estimator that provides the best results for the given image.
- middle grey
- Set the fulcrum point for the contrast slider. This is equivalent to the contrast fulcrum slider on the color balance module. If the contrast slider is set to 0 this slider will not have any effect.
- Equivalent to increasing the gamma factor slider in the color balance module. Moving the slider to the right will increase the brightness of the image, with an emphasis on the mid-tones.
- Equivalent to the output saturation slider on the color balance module, this slider affects the saturation, or brilliance and intensity of the colors. Moving the slider to the right will increase the amount of color in the image; moving the slider to the left will reduce the amount of color in the image.
- Accentuate the colors of the image without adding unnatural colors, as it’s often the case with the saturation slider. It works by reducing the lightness of already saturated pixels to make the colors more vivid. You can also achieve some interesting effects by combining it with the saturation slider to target more or less saturated areas of the image.
- Automatically adjust the exposure, taking into account the entire image, or use the color picker to select a rectangular area of the image – the exposure will be automatically adjusted based on the selected region. This allows you to prioritise which parts of the image should be well-exposed.
- This affects the number of pixels that will be clipped to black or white during the auto-exposure calculation. Moving this slider to the right will allow more pixels to be clipped and increase the contrast; moving this slider to the left will compress the image more and lower the contrast.