The color picker reads a color from an image or from a document and sets this color as foreground color.
By holding Shift the background color is set.
The Tool Settings allow to control the size of the area used to read the color values. Beneath fixed values like 1x1 pixel or 3x3 pixel there is the mode Auto. Using this mode PhotoLine calculates the size by itself depending on the current zoom factor of the document. A zoom factor of 100% or larger results in a 1x1 pixel area. On smaller zoom factors a 3x3 pixel or 5x5 pixel area is used.