Many patients with heart disease face limited treatment options. Fortunately, stem cell biology has enabled researchers to produce large numbers of cardiomyocytes, which may be used in drug screens and cell-based therapies. However, current image analysis techniques don’t allow researchers to analyze heterogeneous, multidirectional, striated myofibrils typical of immature cells. Researchers showcase an algorithm that combines gradient methods with fast Fourier transforms to quantify myofibril structures in heart cells.