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.\" RCSid "$Id: rcrop.1,v 1.8 2023/12/12 16:31:45 greg Exp $" |
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.TH RCROP 1 3/14/2022 RADIANCE |
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.SH NAME |
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rcrop - crop RADIANCE matrix or picture |
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.SH SYNOPSIS |
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.B "rcrop row0 col0 nrows ncols" |
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[ |
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.B input |
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[ |
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.B output |
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] |
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] |
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.SH DESCRIPTION |
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.I Rcrop |
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copies the indicated section of a matrix or RADIANCE picture. |
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The four required arguments are the initial row (scanline) to copy, |
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the initial column, the number of rows to copy, and the number of columns |
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to include per row. |
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Note that rows are numbered from 0 at the top of a matrix or picture, |
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and columns are changing fastest in the input, which can have any number |
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of components per matrix element. |
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.PP |
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The input must have a valid header, including dimensions and format, |
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and a header will always be produced. |
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This is similar behavior to |
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.I rmtxop(1). |
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If the input header is missing, one can usually be added with an |
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appropriate call to |
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.I rcollate(1). |
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If an output header is not desired, it can be removed using |
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.I getinfo(1). |
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.PP |
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One cannot specify crop boundaries outside the matrix dimension limits. |
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If a 0 value is specified for the number of rows to copy, then all rows |
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will be copied, starting from row0. |
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Similarly, a 0 value for the number of columns to copy implies all |
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columns >= col0 will be copied. |
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A negative count for the number of rows or columns cuts the |
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corresponding amount off the end(s). |
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.PP |
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Using |
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.I rcrop |
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on a RADIANCE picture rather than |
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.I pcompos(1) |
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corrects the view parameters if present, |
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and preserves the exposure in a way that is compatible with |
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.I evalglare(1). |
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However, one must remember that rows correspond to Y |
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coordinates, and the orientation is reversed from a standard |
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picture, where Y=0 is the bottom scanline. |
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Spectral pictures, as might be produced by |
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.I rtrace(1) |
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or |
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.I rfluxmtx(1), |
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are also supported. |
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.PP |
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All matrix formats are supported, including text (ASCII), binary float |
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and double. |
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The |
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.I rcrop |
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tool also works on encoded normal vector files produced by |
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.I rcode_norm(1) |
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and encoded depth files produced by |
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.I rcode_depth(1). |
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Data is copied verbatim, i.e., there is no internal conversion to |
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another representation, although white space may change in text files. |
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.PP |
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If no input file is given, data will be taken from the standard input. |
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If no output file is specified, data will be copied to the standard output. |
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.SH EXAMPLES |
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To crop a matrix down to 15 rows by 19 columns, |
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starting at row 10 and column 12: |
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.IP "" .2i |
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rcrop 10 12 15 19 input.mtx > output.mtx |
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.PP |
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To extract column 35 from a matrix: |
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.IP "" .2i |
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rcrop 0 35 0 1 orig.mtx > col35.mtx |
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.PP |
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To crop a picture to (X by Y) = (1500 by 1000), |
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starting from upper-left corner: |
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.IP "" .2i |
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rcrop 0 0 1000 1500 orig.hdr cropped.hdr |
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.PP |
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Two ways of computing the inner product of row 15 in matrix 1 by |
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column 27 in matrix 2 and extracting the result without a header, |
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the second command being more efficient: |
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.IP "" .2i |
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rmtxop -fa mat1.mtx mat2.mtx | rcrop 15 27 1 1 | getinfo - |
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.IP "" .2i |
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rmtxop -fa '!rcrop 15 0 1 0 mat1.mtx' '!rcrop 0 27 0 1 mat2.mtx' | getinfo - |
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.SH AUTHOR |
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Greg Ward |
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.SH "SEE ALSO" |
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evalglare(1), pcompos(1), rcalc(1), rcode_depth(1), rcode_norm(1), |
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rcollate(1), rcomb(1), rfluxmtx(1), rmtxop(1), rsplit(1), rtrace(1) |
