Interpolator

This is an extension of the document Helmut Dersch did on Testing Interpolator Quality

Panotools allows 7 different interpolator.  The interpolator is defined on the 'm' line of the script file using 'i'.  Valid values are 0-poly3 (default), 1-spline16, 2-spline36, 3-sinc256, 4-spline64, 5-bilinear, 6-nearest neighbor, 7-sinc1024

The following images have been rotated 5 degrees 36 separate times.  Then a lossless rotation of 180 deg to get back where it started.


Ken Turkowski's Zone Plate line image displayed here at 300% enlargement Image of my back yard displayed with 80% jpg Add to
3000
X
6000
pan
(*1)
rotate a
6000
X
8000
image
(*2)
Original original original original

[6]

Nearest
Neighbor

zp nn line nn picture nn 22 32

[5]

Bilinear

zp bl line bl picture bl 24 34

[0]

Poly 3

zp poly3 line poly3 picture poly3 22 39

[1]

Spline 16

zp spline16 line spline16 picture spline16 24 44

[2]

Spline 36

zp spline36 line spline36 picture spline36 24 56

[4]

Spline 64

zp spline64 line spline64 picture spline64 25 72

[3]

Sinc 256

zp sinc256 line sinc256 picture sinc256 51 548

[7]

Sinc 1024

zp sinc1024 line sinc1024 picture sinc1024 101 1436
Original original original original
PhotoShop
BiCubic
Normal
original original original
PhotoShop
BiCubic
Smoother
original original original
PhotoShop
BiCubic
Sharper
original original original

All times measured with stop watch.

*1 - Time in seconds to convert a 3.5 MP image into a 3000 X 6000 pan.  Image had hfov of 97.  Time includes: converting image, creating mask, feathering, and flattening image.

*2 - Time in seconds to rotate a 6000 X 8000 pixel image 180. Time includes converting image only.

When creating a panorama generally an image is transformed 5 or less times. 
Once to correct image from Chromatic Aberrations, light falloff, etc...
Second to transform from original into pan.
Third to transform patch area to rectangular.
Forth to transform patch back into pan.
Fifth to create cubes faces from pan.

The distortions above is after 36 separate transformations.  With only 5 transformations the distortion will be less.  When making a panorama I always shrink the final pan to 75% or smaller of original size.  This removes the interpolations introduced by the camera when creating pixels from the CCD.  Getting me to the true resolving power of my camera and lens.  Shrinking the image will also hide some of the distortion created from the transformations.
   

References, Links, and Notes:




Page last modified April 18, 2006
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