The histogram shows the color density of the area that is selected
in the preview window. The top histogram represents the scanned raw image,
the bottom histogram represents the enhanced image. In grayscale mode,
there are three sliders in the gray range. The black slider defines the
black point, the white silder the white point and the gray slider the gray
point (gamma). If the rgb default button (in the xsane main window)
is not selected in color mode there are also sliders in the red, the green
and the blue range. In this case a move of a slider of the gray range also
moves the sliders of the color ranges.
The I, R, G and B buttons define if the
intensity, red, green and/or blue
histogram components are shown.
The curve-type button defines if the histogram curves are shown with
pixels or with lines.
The LOG button defines if the densities are displayed linear