A method of inspecting packaging welds comprises the steps of creating a light beam that produces at least one light transition (t) and acquiring a raw matrix image (B(N)) covering the light transition. For each image (B(N)) obtained, a measurement of the diffusion of the light transition is stored. For each of N successive scanning increments, the raw matrix image (B(N)) is used to create an image line in which each pixel receives as its value the measurement in the raw matrix image (B(N)) of the diffusion of at least the light transition. The at least N image lines are stored in succession to obtain a matrix image and the matrix image is analyzed to determine that the weld along said fraction is in conformity when its transverse width remains, at all points, greater than a given minimum.