--- name: "fitrans" section: "1" platform: "linux" package: "fitsh" version: "0.9.4-1" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/fitrans" --- # fitrans(1) performing spatial transformations on the input image ## NAME fitrans - performing spatial transformations on the input image ## SYNOPSIS **fitrans** \[*transformation and options*\] *\* \[*-o\|--output \*\] ## DESCRIPTION The main purpose of this program is to perform specific or generic geometric transformations on the input image. ## OPTIONS ### General options: - **-h**, **--help** Gives general summary about the command line options. - **--long-help**, **--help-long** Gives a detailed list of command line options. - **--wiki-help**, **--help-wiki**, **--mediawiki-help**, **--help-mediawiki** Gives a detailed list of command line options in Mediawiki format. - **--version**, **--version-short**, **--short-version** Gives some version information about the program. - **-i**, **--input** \ Name of the input FITS image file. - **-o**, **--output** \ Name of the output FITS image file. - **-b**, **--bitpix** \ Standard FITS output bitpix value. - **-D**, **--data** \ Output pixel data format specification. ### Spatial transformations: - **-T**, **--input-transformation** \ Name of the file which contains the transformation description.Such a file can be created e.g. by the programs \`grtrans\` or \`grmatch\`. This file contains basically the same set of \ = \ pairs as it is used after the **-t**\|--transformation option (see there). - **-t**, **--transformation** \ Comma-separated list of parameters for the spatial transformation, see section "Parameters for spatial transformations" below. - **-e**, **--shift** \,\ Imply a transformation that shifts the image by \,\. - **--reverse**, **--inverse** Apply the inverse transformation to the image rather than the original one. - **-m** Simple linear interpolation between pixels, with no exact flux conservation (just a multiplication by the Jacobian of the transformation). - **-l** Linear interpolation between the pixels involving exact flux conservation by integrating on the image surface. - **-c** Bicubic spline interpolation between pixels, with no exact flux conservation (just a multiplication by the Jacobian of the transformation). - **-k** Interpolation by integrationg the flux on a biquadratic interpolation surface, yielding exact flux conservation. - **-s**, **--size** \,\ The size of the output image if it should differ from the original image size. - **-f**, **--offset** \,\ Zero-point coordinate of the output image in the input image. ### Parameters for spatial transformations: - type=\ Type of the transformation. In the actual implementation, the only supported type for a transformation is "polynomial". - order=\ Polynomial order for the transformation. - dxfit=\ Comma-separated list of the polynomial coefficients for the X coordinate. The number of coefficients must be 1, 3, 6, ... for the orders 0, 1, 2, ... respectively. - dyfit=\ Comma-separated list of the polynomial coefficients for the Y coordinate. ### Other simple spatial geometric transformations: - **-z**, **--zoom** \, **--zoom-xy** \,\ Zoom the image by the given (integer) factor, involving a biquadratic subpixel-level interpolation and therefore exact flux conservation. - **-r**, **--shrink** \, **--shrink-xy** \,\ Shrink the image by the given (integer) factor(s). - **-d**, **--median** Use a median-based averaging during the shrinking operation. - **-v**, **--truncated-mean** \ Compute a truncated mean during the shrinking operation by rejecting the \ number of lower and upper points. - **--optimistic-masking** Imply some optimism during the shrinking operation: masked pixels are ignored during the averaging process and the final mask will be computed in a complement manner. - **-g**, **--magnify** \, **--magnify-xy** \,\ Same as zooming the image but there is no subpixel-level interpolation. ### Large-scale image smoothing: - **-a**, **--smooth** \ Perform a smoothing on the image. The parameters of the smoothing are the following: - spline Do a spline interpolation smoothing - polynomial Do a polynomial interpolation smoothing - \[xy\]order=\ Spatial order of the smoothing function. The order in the X and Y coordinates can be set independently, by setting "xorder=..." or "yorder=...". - unity Scale the resulting smoothed image to have a mean of 1. - detrend The resulting image will be the original image divided by the best fit smoothed surface. - \[xy\]hsize=\ Do a box filtering with the given halfsize. - mean Use the mean value of the pixels for the box filtering. - median Use the median value of the pixels for the box filtering. - iterations=\ Number of iterations to reject outlier pixels from the box. - lower, upper, sigma=\ Lower, upper or symmetric rejection level in the units of standard deviation. ### Noise estimation: - **-n**, **--noise** Derive an image which reflects the "noise level" of the image. ### Slicing or exploding data cube images: - **-y**, **--layer** \ Layer (z-axis index) of the desired image slice. - **-x**, **--explode** \ Explode the input image into individual planar (two dimensional) FITS image. The basename must contain at least one printf-like tag of %d, %i, %o, %x or %X that is replaced by the appropriate layer number index. - **-y**, **--first-layer** \ Use the specified value for the first layer index. The subsequent layer indices are incremented normally. By default, the index of the first data cube layer is 0. ### Multiple stamp extraction: - **-c**, **--cut** \ Extract stamps with a size defined by the **-s**\|--size argument. The stamps are extracted on a grid, defined by the **-p**\|--step and **-w**\|--count arguments where the stamp grid offset is defined by the **-f**\|--offset argument. The \ should contain two spefic printf-like elements of %x and %y which are replaced by the corresponding stamp indices in the X and Y directions. In order to have some sort of pretty-printing in the file names, the %x and %y parts may have the form of %.\x and %.\y. Note that despite of the %x convention, both %x and %y are printed in decimal system. - **-w**, **--count** \,\ Number of stamps to be extracted in X and Y directions, respectively. - **-s**, **--size** \,\ The size of the output image stamps. - **-p**, **--step** \,\ Step size between the stamps in the units of pixels and in the X and Y directions, respectively. Note that if \ is smaller than \ (or similarly, if \ is smaller than \), then the output stamps will overlap. This might also be intentional for various applications. - **-f**, **--offset** \,\ Zero-point coordinate of the lower-left pixel of the lower-left output stamp (having an index of %x=0 and %y=0) in the frame of the input image. ## REPORTING BUGS Report bugs to \, see also https://fitsh.net/. ## COPYRIGHT Copyright © 1996, 2002, 2004-2008, 2010-2016, 2018-2020; Pal, Andras \