where γ is a constant value of 1 2 or 2 for direct band gap or indirect band gap, respectively. We compute the direct band gap for FA 1-x MA x PbI 3 perovskites, hence, γ = 1 2 . The transformed Tauc curves are then recursively segmented into linear segments that are split in half until every segment achieves a coefficient of determination of R 2 ≥ 0.990. As shown in the bottom panels of Figure , the dark blue markers along the Tauc curve have a higher density along curved Figure : Automatic degradation testing of vision-segmented perovskite deposits. The aging test is started by taking a single image of a reference color chart on the sample holder plate. The chart is swapped with the samples that are continuously degraded under environmental stress for 6 hours and photographed using an RGB camera with 10-second intervals. The segmented color time series is averaged over the pixels in each sample, color calibrated, and analyzed by calculating the instability index from the data. regions, indicating a higher segmentation rate is required to form straight line segments. Once the recursion is complete, each pair of adjacent line segments is iteratively fit with a linear regression line, as shown by the thin red lines in the bottom panels of Figure . The root-mean-square error (RMSE) is computed between each regression line and the Tauc curve within the range of the x-intercept and the Tauc peak location minus one-half of the peak width. Enforcing the RMSE computation within this range was shown to increase fitting accuracy. The band gap, E g , is the x-intercept point of the regression line that minimizes the RMSE.