An effective approach for skew detection and correction of geophysical log image using Hough transform and a priori knowledge

To meet the needs of the log curves vectorization, roller scanner can be used to acquire geophysical log images. However, skews are inevitably introduced during the process of long image scanning. Skew correction is an important step to obtain precise digital log curves. Grid lines in log curves can be applied as the basis for skew detection. The arrangement of both depth line and scale line is analyzed first in the paper; secondly depth line is set as detection target; thirdly Hough transform is used for detection; then image is corrected using rotation transform according to the angle of depth line which varies with depth; at last, an example is given in this paper. Results show that this method is fast with high efficiency and stable running, which is of great practicality.