User's Guide

CONJ

Computes the pixel-by-pixel complex conjugate of a complex-valued image

Function:

CONJ computes the pixel-by-pixel complex conjugate of a complex-valued image.

Parameters:

IN

Input complex image. Specifies the input complex-valued image. If a window is given for IN the window specifications are in terms of complex pixels or pairs of real values. The data type of IN must be Complex (Real*4).

OUT

Output complex image. Specifies the output image which represents the complex conjugate of the input image. OUT has the same size and data type as IN.

Example:

1. LAS> conj in=test.fft out=test.fft.conj

   The complex conjugate of each complex-valued input pixel of TEST.FFT is taken and placed in TEST.FFT.CONJ.

Description/Algorithm:

For each complex-valued input pixel, the real part (first half of the complex pair) is left unchanged, while the imaginary part (second half of the pair) is negated, such that a+ib becomes a-ib. (See User's Notes.)

Nonfatal Error Message:

None.

Fatal Error Message:

1. [Conj-type] Input file has wrong data type - must be real

   Input image is data type other than REAL*4. Respecify REAL*4 input image.

User's Notes:

1. LAS does not currently support a complex data type. Complex numbers are stored as pairs of reals. Thus, although the program does perform a check that the input data type is REAL, it remains the user's responsibility to ensure that the program is employed in a meaningful way.

2. In the event that a window is specified, the starting pixel and number of pixels parameters refer to complex pixels, that is, to pairs of real values.