Resampling Properties


Use this page to configure the way images are re-sampled. This page also selects which transformation is being used to achieve registration.

 

Image Registration Resampling Properties

Transformation

Specifies the mathematical mapping between the marker coordinates in the reference image and the target images.

Shift: Corrects a coordinate displacement in the x and y directions.

Shear: Corrects coordinate displacements, rotation, non-perpendicular axes, and unequal scale in the x and y directions.

Resampling method

Specifies the method used to compute image intensity at fractional pixel coordinates.

Bi-linear: Computes a linear interpolation between pixels in the x and y directions.

Bi-cubic: Computes a 4 term cubic polynomial interpolation between pixels in the x and y directions.

Nearest Neighbor: Uses the pixel nearest to the transformed coordinate instead of re-sampling the pixel values. This inflates the FWHM by about 0.3 pixels but preserves the noise structure of the image, which can have important consequences when aperture photometry or image cleaning will be done on the registered images.

Reference Image

Select the reference image onto which the transformation mapping is computed. This image is not resampled.

Residuals

Opens a window listing a table of residuals that result from the transformation equations. The residuals show the distance, in pixels, between the marker points and their predicted positions in the registered images. This can be used to spot bad points that can give a bad transformation solution and should be deleted before the transformation is recalculated without them.

 Conserve Flux

Check this box to conserve flux (sigma per unit time) in the transformation equations. For example, if conserving flux and the output pixel is 1/2 as wide and 1/2 as tall, then the signal is 1/4 as high.

 Save Undo Copy

Check this box to save an Undo copy of each image before registration is done. This allows you to recover the original images if you want to re-do the registration. Uncheck this box to save memory, which can be a critical issue when registering many, large images that may need all the memory available on the computer.

 Verbose

Check this option to give verbose listing of registration results.

Recommendations

Related Topics

Registration Properties Dialog, Background Properties