Methods are provided for determining whether an image captured by a capturing device is clean or dirty. These methods include: receiving the image captured by the image capturing device; splitting the received image into a plurality of image portions according to predefined splitting criteria; performing, for each of at least some of the image portions, a Laplacian filter of the image portion to produce a feature vector including Laplacian filter features of the image portion; providing the feature vectors to a first machine learning module that has been trained to produce a clean/dirty indicator depending on corresponding feature vector, the clean/dirty indicator including a probabilistic value of cleanness or dirtiness of corresponding image portion; and determining whether the image is clean or dirty depending on the clean/dirty indicators produced by the first machine learning module. Systems and computer programs suitable for performing such methods are also provided.