SELECTING OPTIMAL IMAGE FROM MOBILE DEVICE CAPTURES

Embodiments of the disclosed technologies include a method of capturing, using a mobile device, a best-focused image of a skin surface of a subject, the method including: setting a camera of the mobile device to a fixed focal length; capturing, using the camera, a current image of a plurality of images of the skin surface, the plurality of images having a sequence and including a first previous image captured, using the camera, previously to the current image and a second previous image captured, using the camera, previously to the first previous image; producing a modified image from the current image; transforming the modified image, using a Laplacian pyramid, to produce a plurality of first luminance values from the modified image and a plurality of second luminance values from the plurality of first luminance values; averaging a plurality of first squared values, each including a square of a corresponding first luminance value of the plurality of first luminance values, to produce a first energy value; averaging a plurality of second squared values, each including a square of a corresponding second luminance value of the plurality of second luminance values, to produce a second energy value; calculating a first ratio of the first energy value to the second energy value; calculating, as an average first energy value of the first previous image, an average of the first energy value, a corresponding first energy value of the first previous image, and a corresponding first energy value of the second previous image; calculating, as an average first ratio of the first previous image, an average of the first ratio, a corresponding first ratio of the first previous image, and a corresponding first ratio of the second previous image; determining that the first previous image is one of a plurality of valid images, where each valid image of the plurality of valid images is an image of the plurality of images and has: a corresponding average first energy value above an energy threshold value; and a corresponding average first ratio approximately equal to 1.0; determining that a first valid image of the plurality of valid images is the best-focused image, where the first valid image has a corresponding average first energy value that is greater than the corresponding average first energy values of: a previous valid image captured immediately before the first valid image; and a subsequent valid image captured immediately after the first valid image; and performing a