When line structured light is used in 3D measuring with wide view field, the extraction of light stripe center becomes difficult because of the complex image background and non-uniform illumination. A line structured light center extraction method based on peak intensity is proposed in the paper. The peak intensity value of every pixel is calculated and the image is segmented according to the threshold related to the peak intensity, thus the structured light stripe center is extracted. Line structured light stripe images with wide view field have been processed by the proposed method. The experimental results indicate that our proposed method extracts the line structured light stripe center accurately when the background is complex, the illumination is non-uniform and the view field is wide.
The contrast and color fidelity of aerial images are usually seriously weakened and many features are covered because of atmospheric scattering and other factors. By using global features, low contrast images can be improved globally and the enhanced images may have little noise and ringing artifacts, but overexposure or underexposure may occur on some parts. By using local features, the details appear better, but it may lead to noise and ringing artifacts when the contrast gain is too large. In the paper, a new contrast enhancement method with adaptive gamma correction based on the weighting of global and local gray-scale mean is proposed. The adaptive gamma parameter which is obtained by incorporating the global and local gray-scale mean into the weighting distribution, is used to correct the gray value of each pixel in the image. Aerial images taken by DJI unmanned aerial vehicle with Inspire 2 at an altitude of 500 meters have been processed in the proposed method. Experimental results indicated that the proposed algorithm performs even better than the current mainstream methods in contrast enhancement for low visibility aerial images.