Titan: the anomalous "circular" surface features are "camera artifacts"

Caption NASA originale from Planetary Photojournal:"The large, bottom image shows a complex interplay between dark and bright material on Titan's surface. This image was taken at a range of about 340.000 Km and the entire view is approximately 2.000 Km across. The surface appears to have been shaped by multiple geologic processes. Although a few "circular features" can be seen, there are no features that can be definitively identified as impact craters. The 3 smaller images show details of some of the features seen within the larger scene. The image on the upper right shows a scene approximately 500 Km across in which bright and dark bands of material span Et to Wt. The upper middle and upper right images show bright material surrounded by dark material in scenes approximately 300 Km across. The dark circular feature that appears at the top of each of the upper images is an artifact that was not removed by the preliminary image processing. There are no shadows or topographic shading visible in these images".