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IP T - Triangular InterPolation

(01/13/94)

PURPOSE

Interpolates a 2-D picture using triangular interpolation

SEE ALSO

IP [interpolation, 2D and 3D]
FP [Fourier interpolation]

USAGE

.OPERATION: IP T

.INPUT1 FILE: H_PIC001
[Enter the name of the file to be interpolated.]

.OUTPUT FILE: H_IMG025
[Enter the file where the interpolated image is to be kept.]

.ENTER DIMS NSAM,NROW: 128,128
[Enter the dimensions of the interpolated image.]

NOTES

  1. This operation can be used for either interpolation or extrapolation.

  2. The output image does not have to have the same proportions (ratio NSAM/NROW) as the input picture.

  3. For a rectangular input image, only the new side length (NSAM) of the output image need be entered. The other side length (NROW) will then be computed assuming the same proportions as the input image. For example, let the input image have the size 60x40. Then the sequence .ENTER DIMS NSAM, NROW: 120 will have the same effect as .ENTER DIMS NSAM, NROW: 120,80

  4. For an output picture with dimensions exactly two times smaller than those of an input picture the adding of four neighbouring pixels is done. The resulting picture contains frequencies up to 0.25 (roughly) and has improved SNR (two times). For an output picture with dimensions exactly four times smaller than those of an input picture the adding of sixteen neighbouring pixels is done.

  5. The triangular interpolation scheme is used for any image sizes.

  6. THE MEMORY NEEDED IS (NSAM*NROW*NSLICE+NSAM) in MAXMEM.

  7. The triangular interpolation is for 2-D pictures only.

SUBROUTINES

TRINTER

CALLER

UTIL2

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