1. It can perform a unary (single-operand) operation on each pixel of an input image.
2. It can perform a binary (two-operand) operation between each pixel of an input image and a scalar value.
3. It can perform a binary (two-operand) operation between each pixel of an input image and the corresponding pixel of a second image. The mode, operation, and operands are specified by command line options. Input images come from a data file; the specified operation is performed on each to pro duce an output image of the same properties.
When the operation is a binary one between two images (case 3, above), the second input comes from a separate file, and it may have the same number of bands as the first input image, in which case band i of the output image is formed from band i of both input image; or formed from band i of the first input image and band 0 of the second.
By means of the -min and -max options, you can specify bounds for clipping output pixel values.
When -op specifies a binary operation, either -image or -value must be specified. The and, or, and xor operations can only be performed with images having integer pixel representations (not float or double). A floating point result (such as what exp produces) is rounded to the nearest inte ger for storing in an integer output pixel. Clipping of output pixel values and arithmetic exceptions are reported by means of warning messages.
vop
-in | Specifies a Vista data file containing the input images. These images serve as the first operand of a binary operation, or the only operand of a unary one. |
-out | output image |
-op | Specifies the operation. Possible values: abs,exp,log,not,sqrt,square,add,and,dist,div,max,min,mult,or,sub,xor |
-value | Specifies a scalar constant to be used as the second operand of a binary operation. |
-image | Specifies a Vista data file containing a single image to serve as the second operand of a binary operation. |
-min | Sets a lower bound for clipping output pixel values. Default: the minimum value that can be represented by an output pixel. |
-max | Sets an upper bound for clipping output pixel values. Default: the maximum value that can be represented by an output pixel. |