Industrial radiography (RT) is one of the most important non-destructive testing (NDT) methods for the welding defects (e.g. cracks) identification. In the radiography film interpretation, the precise detection of the cracks depends on the interpreter person’ capabilities and skills as well as the image quality of the films.Industrial radiography films often suffer from the low image quality. Therefore, there is a need for accuracy increasing of the defect detection in these type of the radiography images. Cracks have the specific frequency domain feature due to the shape, i.e. very narrow width in comparison with its length. Different frequency and time based image processing techniques can be implemented for the analyzing of the cracks defects. In this research, a wavelet based method and an empirical mode decomposition (EMD) method were used and compared for the detection and analyzing of the welding crack zone. In both methods final image was created as a combination of the original image decomposition components. Then the crack defects have been surveyed in the processed images. The EMD method showed the better results in the crack detection in the comparison of the proposed wavelet method. Although the contrast of the processed images were decreased with EMD method, but also the location and the shape of the cracks clearly appeared.