HP LaserJet 3015 - Manual (Page 77)

Color
You can set the color values to the following settings when scanning.
Setting Recommended use
Color Use this setting for high-quality color photos or
documents in which the color is important.
Black and White Use this setting for text documents.
Grayscale Use this setting when file size is an issue or when
you want a document or photograph to be
scanned quickly.
ENWW Scanner resolution and color 67