Fig. 2

Test cases of photoreceptors against output from Butler’s model. a–d A red/green photoreceptor that satisfies the assumptions required for the photoconversion cross-sections to be calculated using Butler’s method. a Circles are the target photoconversion cross-sections used to create the synthetic data (denoted ‘Input’); blue and green lines show the photoconversion cross-sections calculated using Butler’s model (denoted ‘Butler’); black and red lines show the photoconversion cross-sections obtained using our optimisation algorithm (denoted ‘Opt’). b Quantum yields obtained from Butler’s model (denoted ‘Butler’) and our optimisation algorithm (‘Opt’) compared to the target values (‘Input’). c, d Simulations of absorption spectra (red lines) created using the optimal values from our algorithm compared to synthetic datasets (circles). e–h Same as in a–d except for a photoreceptor with photoconversion cross-sections that do not satisfy the conditions required to be calculated by Butler’s model