## IP T - Interpolate/Resize - using Triangular interpolation

(08/8/08)

PURPOSE

Interpolates/resizes an image using triangular interpolation. Not for use with volumes. Very poor quality interpolation, use another interpolation method instead!   Example.

 IP [Interpolate/Resize using bilinear/trilinear interpolation] IP FS [Interpolate/resize image/volume - using Fourier based cubic spline ||] IP FT [Interpolate/Resize - using Fourier Transform ||] DC [Decimate image/volume]

USAGE

.OPERATION: IP T

.INPUT FILE: PIC001
[Enter the name of the file to be resized.]

.OUTPUT FILE: IMG025
[Enter the file where the resized image is to be kept.]

.OUTPUT DIMENSIONS, NX & NY: 128, 128
[Enter the dimensions for the output 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 NX/NY) as the input picture.

3. For a rectangular input image, only the new row length (NX) of the output image need be entered. The other side length (NY) 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:
.OUTPUT DIMENSIONS, NX & NY: 120
will have the same effect as:
.OUTPUT DIMENSIONS, NX & NY: 120, 80

4. For an output picture with dimensions exactly two times smaller than those of an input picture, addition 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 addition of sixteen neighbouring pixels is done.

5. This operation works on images only, not for volumes.

SUBROUTINES

TRINTER

CALLER

UTIL2