Images are essential for many Android applications or apps. Although images play a critical role in app functionalities and user experience, inefficient or improper image loading and displaying operations may severely impact the app performance and quality. Additionally, since these image loading defects may not be manifested by immediate failures, e.g., app crashes, existing GUI testing approaches cannot detect them effectively. In this paper, we identify five anti-patterns of such image loading defects, including image passing by intent, image decoding without resizing, local image loading without permission, repeated decoding without caching, and image decoding in UI thread. Based on these anti-patterns, we propose a static analysis technique, \textsf{IMGDroid}, to automatically and effectively detect such defects. We have applied \textsf{IMGDroid} to a benchmark of 21 open-source Android apps, and found that it not only successfully detects the 45 previously-known image loading defects but also finds 15 new such defects. Our empirical study on 1,000 commercial Android apps demonstrates that the image loading defects are prevalent.