Density Histogram

To aid placing the markers and, in some cases, improve the scan quality the Density Histogram can be used. It depicts the grayscale density1 of the pixels along the horizontal and vertical cursor axis at the current position. Pixel 0 is the actual cursor position. The histogram covers ±5 pixels to the left (up) and right (down) of the current position. This is especially useful for fine adjustments with Alt (Option) + arrow. Launch it via View->Density Histogram or Ctrl+G (macOS: ⌘+G). By default the pixel along the horizontal (red) and vertical (blue) axis are shown. A pull-down menu in the upper left allows to hide either the horizontal or vertical axis density.

1 The grayscale density is obtained by converting a pixel into its grayscale equivalent and inverting the value so that high numbers indicate higher densities (blacker). White has a value of 0 and black is 255.