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.\" RCSid "$Id" |
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.\" RCSid "$Id$" |
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.TH PCOMB 1 8/31/96 RADIANCE |
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.SH NAME |
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pcomb - combine RADIANCE pictures. |
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pcomb - combine RADIANCE pictures and/or float matrices |
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.SH SYNOPSIS |
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.B pcomb |
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[ |
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.B -h |
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][ |
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.B -w |
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][ |
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.B -ff |
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][ |
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.B "\-x xres" |
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][ |
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.B "\-y yres" |
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] |
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.SH DESCRIPTION |
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.I Pcomb |
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combines equal-sized RADIANCE pictures and sends the result to the |
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standard output. |
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combines equal-sized RADIANCE pictures or raw float matrices |
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and sends the result to the standard output. |
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By default, the result is just a linear combination of |
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the input pictures multiplied by |
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the input pixels multiplied by |
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.I \-s |
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and |
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.I \-c |
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.I \-e |
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and |
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.I \-f |
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options. |
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options, similar to |
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.I rcalc(1). |
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(The variable and function definitions in each |
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.I \-f source |
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file are read and compiled from the RADIANCE library |
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where it is found.)\0 |
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Negative coefficients and functions are allowed, and |
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.I pcomb |
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will produce color values of zero where they would be negative. |
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will produce color values of zero where they would be negative |
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unless the |
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.I \-ff |
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option is used to specify floating-point matrix output. |
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.PP |
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The variables |
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.I ro, |
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.I gi(n) |
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and |
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.I bi(n) |
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give the red, green and blue input values for |
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picture |
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give the red, green and blue values for |
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input |
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.I n. |
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To access a pixel that is nearby the current one, these functions |
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also accept optional x and y offsets. |
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For example, |
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.I ri(3,-2,1) |
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would return the red component of the pixel from picture 3 |
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would return the red component of the pixel from input 3 |
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that is left 2 and up 1 from the current position. |
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Although x offsets may be as large as width of the picture, |
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y offsets are limited to a small window (+/- 8 pixels) due to efficiency |
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Although x offsets may be as large as width of the input, |
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y offsets are limited to a small window (+/- 32 pixels) due to efficiency |
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considerations. |
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However, it is not usually necessary to worry about this problem -- |
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if the requested offset is not available, the next best pixel is |
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.PP |
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For additional convenience, the function |
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.I li(n) |
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is defined as the input brightness for picture |
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is defined as the input brightness for input |
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.I n. |
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This function also accepts x and y offsets. |
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.PP |
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gives the number of input files present, |
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and |
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.I WE |
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gives the white efficacy (lumens/brightness) for pixel values. |
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gives the white efficacy (lumens/brightness) for pixel values, |
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which may be used with the |
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.I \-o |
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option or the le(n) values to convert to absolute |
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photometric units (see below). |
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The variables |
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.I x |
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and |
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.I "re(n), ge(n), be(n)," |
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and |
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.I le(n) |
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give the exposure values for picture |
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give the exposure values for input |
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.I n, |
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and |
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.I pa(n) |
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gives the corresponding pixel aspect ratio. |
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Finally, for pictures with stored view parameters, |
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Exposure values will be set to 1.0 for inputs with the |
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.I \-o |
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option set. |
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Finally, for inputs with stored view parameters, |
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the functions |
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.I "Ox(n), Oy(n)" |
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and |
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.I Oz(n) |
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return the ray origin in world coordinates for the current pixel |
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in picture |
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in input |
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.I n, |
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and |
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.I "Dx(n), Dy(n)" |
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will return a negative value, and |
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.I S(n) |
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will return zero. |
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The first input input with a view is assumed to correspond to the |
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view of the output, which is written into the header. |
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.PP |
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The |
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.I \-h |
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option may be used to reduce the information header size, which |
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can grow disproportionately after multiple runs of |
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.I pcomb |
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and/or |
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.I pcompos(1). |
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The |
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.I \-w |
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option can be used to suppress warning messages about invalid |
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calculations. |
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The |
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.I \-o |
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option indicates that original pixel values are to be used for the next |
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picture, undoing any previous exposure changes or color correction. |
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input, undoing any previous exposure changes or color correction. |
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.PP |
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The |
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.I \-x |
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and |
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.I bo |
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will be used to compute each output pixel. |
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This is useful for producing simple test pictures for various |
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This is useful for producing simple test inputs for various |
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purposes. |
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(Theoretically, one could write a complete renderer using just the |
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functional language...) |
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.PP |
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The standard input can be specified with a hyphen ('-'). |
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A command that produces a RADIANCE picture can be given in place of a file |
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A command that produces a RADIANCE picture or float matrix |
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can be given in place of a file |
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by preceeding it with an exclamation point ('!'). |
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.SH EXAMPLES |
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To produce a picture showing the difference between pic1 and pic2: |
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.IP "" .2i |
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pcomb -e 'ro=ri(1)-ri(2);go=gi(1)-gi(2);bo=bi(1)-bi(2)' pic1 pic2 > diff |
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pcomb \-e 'ro=ri(1)\-ri(2);go=gi(1)\-gi(2);bo=bi(1)\-bi(2)' pic1 pic2 > diff |
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.PP |
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Or, more efficiently: |
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.IP "" .2i |
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pcomb pic1 -s -1 pic2 > diff |
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pcomb pic1 \-s \-1 pic2 > diff |
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.PP |
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To precompute the gamma correction for a picture: |
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.IP "" .2i |
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pcomb -e 'ro=ri(1)^.4;go=gi(1)^.4;bo=bi(1)^.4' pic > pic.gam |
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pcomb \-e 'ro=ri(1)^.4;go=gi(1)^.4;bo=bi(1)^.4' inp.hdr > gam.hdr |
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.PP |
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To perform some special filtering: |
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.IP "" .2i |
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pcomb -f myfilt.cal -x xmax/2 -y ymax/2 input.pic > filtered.pic |
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pcomb \-f myfilt.cal \-x xmax/2 \-y ymax/2 input.hdr > filtered.hdr |
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.PP |
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To make a picture of a dot: |
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.IP "" .2i |
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pcomb -x 100 -y 100 -e 'ro=b;go=b;bo=b;b=if((x-50)^2+(y-50)^2-25^2,0,1)' > dot |
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pcomb \-x 100 \-y 100 \-e 'ro=b;go=b;bo=b;b=if((x-50)^2+(y-50)^2\-25^2,0,1)' > dot |
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.SH ENVIRONMENT |
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RAYPATH the directories to check for auxiliary files. |
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.SH AUTHOR |
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Greg Ward |
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.SH "SEE ALSO" |
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calc(1), getinfo(1), pcompos(1), pfilt(1), rpict(1) |
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getinfo(1), icalc(1), pcompos(1), pfilt(1), rcalc(1), |
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rmtxcomb(1), rmtxop(1), rpict(1) |
