When grayscale is selected only grayscale information is sent to a grayscale driver for increased speed. Selecting Send Color Bitmaps As Grayscale when using a color printer driver with a color printer should not affect output. It is a useful option for artwork containing a lot of black text, but it should be used with caution on artwork with a high graphics content. On , Off PostScript Level 2 uses a faster method for rendering vector curves and lines. This option specifies whether to compensate for resolution effects that may be noticeable when line thickness is a small number of device pixels.
Line width can vary when printed, depending on how they line up with pixels.
Sometimes this method can change the appearance of your images. If this happens, you can disable the PostScript 2 Stroke Adjust option. If they do this, make sure you find out whether the service bureau wants you to let them resolve the DCS links. If they want to resolve the links themselves, then you will have to change the Resolve DCS Links setting to Leave DCS Links Unresolved. This represents the number of pixels by which each bitmap chunk overlaps the next.