  Currently, most deep learning methods cannot solve the problem of scarcity of
industrial product defect samples and significant differences in
characteristics. This paper proposes an unsupervised defect detection algorithm
based on a reconstruction network, which is realized using only a large number
of easily obtained defect-free sample data. The network includes two parts:
image reconstruction and surface defect area detection. The reconstruction
network is designed through a fully convolutional autoencoder with a
lightweight structure. Only a small number of normal samples are used for
training so that the reconstruction network can be A defect-free reconstructed
image is generated. A function combining structural loss and $\mathit{L}1$ loss
is proposed as the loss function of the reconstruction network to solve the
problem of poor detection of irregular texture surface defects. Further, the
residual of the reconstructed image and the image to be tested is used as the
possible region of the defect, and conventional image operations can realize
the location of the fault. The unsupervised defect detection algorithm of the
proposed reconstruction network is used on multiple defect image sample sets.
Compared with other similar algorithms, the results show that the unsupervised
defect detection algorithm of the reconstructed network has strong robustness
and accuracy.
