USGS MIPS Derive Documentation

USGS MIPS Derive Documentation

This program calculates the first derivative, or first difference, between adjacent pixels in an image . The difference can be in any one of three user specified directions: horizontal, vertical, or diagonal. The following equations are used to calculate the difference:

Horizontal = A - B + Addback
Vertical   = A - C + Addback
Diagonal   = A - D + Addback

where,

A, B, C and D are pixels adjacent to each other in the image

---------
| A | B |
----+----
| C | D |
---------

and,

Addback is either a user specified constant or a default value used to ensure that positive unsigned 8-bit numbers are generated if the input is unsigned 8-bit, or to center the output DN range somewhere else than zero if the input file is 16 or 32-bit.

Files

This program requires as input an unsigned 16-bit , or one labels
Mosaic labels
Projection labels
Sonar labels
Navigation file
History file

Parameters

HORZ, VERT or DIAG: These parameters are used to select the desired direction of the first derivative and can be either horizontal, vertical or diagonal. The default direction is HORZ.
ADBK: This parameter is used to keep the output DNs in the desired range depending on the bit type of the input image. For unsigned 8-bit images the default is 127 so that only positive 8-bit integer values are generated(0 - 255), and for signed 16-bit and 32-bit floating point the default value is 0.

Uses

This program is useful for enhancing edges in an image; however, since it applies directional filters it will not enhance edges which are in the same direction as the filter. For example, the horizontal option will enhance vertical/all non-horizontal edges, but will not enhance horizontal edges(it will actually remove/suppress horizontal features/linear features). Also, if applied to either DEM or Bathy data it generates a shaded relief image having a 45 degree sun elevation angle.

Examples

From left to right, original Landsat MSS Band 6, horizontal derivative and vertical derivative.

[Example Image]