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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 "\-x xres" |
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would return the red component of the pixel from picture 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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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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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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.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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.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 AUTHOR |
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Greg Ward |
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.SH "SEE ALSO" |
