1. A computer-implemented method for calculating an image quality metric for evaluating a quality of a digital image, comprising: receiving data of the digital image, the data including data of a plurality of pixels comprising the digital image; denoising the data of the digital image to obtain a denoised digital image; identifying a plurality of edges in the denoised digital image; determining an edge profile of each of the identified edges; determining a grayscale angle for each identified edge based on the edge profile associated with the identified edge; and calculating the image quality metric based on a weighted average of the grayscale angles for all of the identified edges for the digital image; denoising the digital image by decomposing the digital image using wavelet decomposition to create a decomposed and denoised image; and calculating the weighted grayscale angle using a normalized power spectrum associated with the wavelet decomposition.