A Method for Recovering JPEG Files Based on Thumbnail

File carving is a digital forensic technique which extracts file from unstructured data stream. Reassembling fragments data from disk to recover JPEG file is always a difficult problem. This paper presents an approach for recovering JPEG files from fragment data based on thumbnails. Using the mapping relation between the thumbnail and the original image, the image fragments can be rearranged to restructure the original image. Experimental results show that the proposed method is effective and accurate to recover JPEG files.