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{ RCSid $Id$ } |
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{ |
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Filter Kernal set-up for pcomb. |
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|
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5/22/92 Greg Ward |
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Usage: |
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pcomb -x xres -y yres -f kern.cal -f filt.cal input.pic > output.pic |
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The file "kern.cal" must define the constant function kern(x,y), which |
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describes how the kernal behaves as a function of offset in x and y |
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(measured in fractional pixels in the destination image). |
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} |
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hmag : xres/xmax; |
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vmag : yres/ymax; |
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step : (hmag+vmag)/8; |
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hsum(xmin,xmax,y) : if(step/2+xmin-xmax, 0, |
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kern(xmin+step/2,y) + hsum(xmin+step,xmax,y)); |
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sum(xmin,ymin,xmax,ymax) : if(step/2+ymin-ymax, 0, |
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hsum(xmin,xmax,ymin+step/2) + sum(xmin,ymin+step,xmax,ymax)); |
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k(ox,oy) : sum(ox-hmag/2,oy-vmag/2,ox+hmag/2,oy+vmag/2); |
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K00 : k(-1,-1); K01 : k(-1, 0); K02 : k(-1, 1); |
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K10 : k( 0,-1); K11 : k( 0, 0); K12 : k( 0, 1); |
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K20 : k( 1,-1); K21 : k( 1, 0); K22 : k( 1, 1); |
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sumtotal : K00+K01+K02+K10+K11+K12+K20+K21+K22; |
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|
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f(p) = ( K00*p(1,-1,-1) + K01*p(1,-1, 0) + K02*p(1,-1, 1) + |
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K10*p(1, 0,-1) + K11*p(1, 0, 0) + K12*p(1, 0, 1) + |
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K20*p(1, 1,-1) + K21*p(1, 1, 0) + K22*p(1, 1, 1) ) / sumtotal; |
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|
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ro = f(ri); |
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go = f(gi); |
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bo = f(bi); |
