Why do blue and/or red areas appear on the image?

Why do blue and/or red areas appear on the image?

Nebulb allows you to display both the burned areas of the image (in red) and the areas that are completely black (in blue).

For this you can use the triangular buttons in the histogram:





  1. The blue triangular button is the warning button for black areas. Activating this button highlights in blue the pixels of the image that are completely black.
  1. The orange triangular button is for the burned area warning. When this button is activated, pixels in the image that are completely white are highlighted in red.