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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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][ |
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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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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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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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.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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.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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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 pictures with stored view parameters, |
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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 picture with a view is assumed to correspond to the |
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view of the output picture, which is written into the header. |
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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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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: |
