By selecting the second tab using the green highlighted tab selector the local contrast and light corrections panel appears.
This filter serves very well when requiring to reveal very faint details by increasing their contrast. At the same time it will leave very distinct details that already had higher contrast mostly unharmed. This filter corresponds to the G'MIC filter "Enhance local contrast". Be aware that using this slider will significantly slow down the overall processing because this feature from G'MIC is quite slow. It is therefor disabled by default and can only be enabled by selecting the "unlock" checkbox.
Moreover there are 3 sliders that work on different detail size ranging from small to medium to large details. When increasing the value for small details it will increase the contrast on the smallest details found in the image. Medium details are usually cloud bands such as on Jupiter and Saturn. Large details will work on larger areas such as plaines on the moon. This function works in a similar way as the lower sliders in wavelet sharpening functions of other software..
This menu offers a couple of ways to improve the light, such as gamma, overall contrast, the brightness and background darkening. This menu is quite self explanatory. By increasing the brightness you can use the histogram window to prevent overexposing the image.
Lightness makes the overal image lighter. This slider may be useful to bring forward faint details such as the D and R rings on Saturn.
In order to prevent the background from lighting up you may want to select the "Preserve dark background" checkbox. This will keep the background as dark as it is in the unprocessed image stack, no matter what value is chosen for lightness.
Finally the darken background slider allows you to make the background darker. This can be useful when an image was taken during daylight or dusk/dawn.