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{ RCSid $Id: sky2spectra.cal,v 1.2 2024/02/29 15:40:56 greg Exp $ } |
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{ |
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Convert RGB sky to spectral sky using, for example: |
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|
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rcomb -fc -c XYZ input_sky.hdr -f skyfact.cal -f sky2spectra.cal \ |
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-c `cnt 20 | rcalc -f skyfact.cal -e 'wl=780-20*($1+.5)' \ |
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-e '$1=S0(wl);$2=S1(wl);$3=S2(wl)'` \ |
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| getinfo -r 'WAVELENGTH_SPLITS= 780 588 480 380' \ |
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> output_sky.hsr |
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The above produces a 20-component output from 380 to 780 nm. |
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|
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Similarly, you can convert an RGB sky vector or matrix using: |
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|
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rcomb -ff -c XYZ color_sky.mtx -f skyfact.cal -f sky2spectra.cal \ |
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-c `cnt 20 | rcalc -f skyfact.cal -e 'wl=780-20*($1+.5)' \ |
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-e '$1=S0(wl);$2=S1(wl);$3=S2(wl)'` \ |
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| getinfo -r 'WAVELENGTH_SPLITS= 780 588 480 380' \ |
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> spectral_sky.mtx |
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|
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by G. Ward |
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2/29/2024 |
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} |
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|
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in_Y = ci(1,2); |
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xyzM = 1/(ci(1,1) + in_Y + ci(1,3)); |
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in_x = ci(1,1)*xyzM; |
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in_y = in_Y*xyzM; |
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|
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in_M1 = M1(in_x,in_y); |
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in_M2 = M2(in_x,in_y); |
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co_Multiplier = in_Y / (S0normf + in_M1*S1normf + in_M2*S2normf) / 179; |
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co(n) = co_Multiplier * select(n, 1, in_M1, in_M2); |
