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{ RCSid $Id: fisheye_corr.cal,v 1.4 2016/09/14 18:17:59 greg Exp $ } |
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{ |
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Correct fisheye image using a distortion function: |
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rad(r) = function of r in [0,.5] range, returing same |
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This function takes the pixel distance from the image center, where |
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1.0 is the full width of the image constituting 180-degrees of view. |
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The output is the corrected distance from the center for the output. |
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(If your function is the inverse of this, set map_inverse=1.) |
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pcomb -f fisheye_corr.cal -e 'rad(r)=my_function(r)' \ |
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-o fisheye.hdr > corrected.hdr |
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We also clear the region outside the r=[0,.5] circle to black. |
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If this is all you want to do, use "rad(r)=r". |
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If you know you have a solid-angle preserving distortion, use |
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"rad(r)=mapsolid(r)" or leave off definition, as this is the default. |
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Note that you will need to add back the VIEW= line to the header, e.g.: |
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echo "VIEW= -vta -vh 180 -vv 180" > corrected.hdr |
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(above_command) >> corrected.hdr |
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Or: |
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(above_command) | getinfo -a "VIEW= -vta -vh 180 -vv 180" \ |
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> corrected.hdr |
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} |
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xc : xres/2; |
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yc : yres/2; |
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sq(x) : x*x; |
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map_inverse = -1; { change to 1 if rad(r) is inverse mapping } |
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inp_r = sqrt(sq((x-xc)/xres) + sq((y-yc)/yres)); |
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mapped_r = rad(inp_r); |
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rmult = if(map_inverse, inp_r/(mapped_r+1e-7), mapped_r/(inp_r+1e-7)); |
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xoff = (x-xc)*(1-rmult); |
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yoff = (y-yc)*(1-rmult); |
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ro = if(.5-inp_r, ri(1,xoff,yoff), 0); |
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go = if(.5-inp_r, gi(1,xoff,yoff), 0); |
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bo = if(.5-inp_r, bi(1,xoff,yoff), 0); |
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{ Radius adjustment for equisolid-angle projection to equidistant (-vta) } |
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mapsolid(r) : 2/PI*asin(sqrt(2)*r); |
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{ Default correction function } |
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rad(r) = mapsolid(r); |
