A method for identifying types of flaws in a composite object includes: a) rapidly heating the surface of the object; b) recording pixel intensities in a sequence of IR images; c) determining temperature-versus-time data for each of the pixels from the IR images; and d) determining what type of flaw if any corresponds to each of the pixels using the temperature-versus-time data determined in step (c). A contrast curve derived from the temperature-versus-time data may be used in determining what type of flaws if any corresponds to each of the pixels. The contrast curve may be determined by subtracting a synthetic reference curve from a temperature time curve from the temperature-versus-time data. The types of flaws may be determined from size and/or shapes of peaks in the contrast curves. Some flaws are delaminations, layers of porosity, and uniformly distributed porosity.