Modified image, saturation and contrast adjusted. This picture intrigues me. The picture was taken half way up a very steep climb in Brecon, UK. When I took the picture I did not see anything. The frame before and after have no markings, I have taken over 3000 pictures with this camera (Canon 650d fitted with a Canon 15 to 85 zoom) and have had no similar markings. The day was very windy, a forest was 600 to 700 feet below and the area we were walking in is short rough grassland, the spots of white in the far hillside are sheep this gives an idea of scale. The shutter speed was 160th sec at f7.1 at 15.0mm wide angle, 100 ISO, image size was 18mp. I am familiar with the use of Photoshop but nothing has been altered from the original image apart from contrast, saturation and crop to enable a large zoom image. I would be interested in any comments regarding what this object could be or any suggestions regarding where to look for an artifact which could have caused this strange effect.
Original image as produced by the camera.
Cropped to give a close up of object, contrast and saturation adjusted.