1. A method for detecting blemishes in a RGB image captured by an electronic device, the method comprising steps of: reading the RGB image from the electronic device; converting the RGB image to a grey image and measuring a length and a width of the grey image; defining a center point of the RGB image by moving a rectangle finder on the grey image and calculating an average grey value of each area framed by the rectangle finder; analyzing pixels of each radial radiating from the center point of the RGB image for detecting blemishes in the RGB image; taking count of blemishes in the RGB image; comparing a total blemish number with a maximum tolerable blemish number; if the total blemish number in the RGB image exceeds the maximum tolerable blemish number, displaying an indication of test failure; and if the total blemish number in the RGB image does not exceeds the maximum tolerable number, displaying an indication of test pass; wherein a blemish is a change in a trend of the pixel values along each radial.