Embodiments of the present disclosure provides an image processing method, comprising: acquiring an initial image comprising an image of pupil; acquiring an accumulative histogram set of grayscale values of pixels in the initial image; determining a threshold for binarizing the initial image according to a grayscale value corresponding to a target region in respective accumulative histograms in the accumulative histogram set, wherein the target region corresponds to the image of pupil in the initial image; and binarizing the initial image according to the threshold. An image processing apparatus and a wearable device are further provided.