1. An image recognizing method, recognizing at least one testing image according to a plurality of classes, wherein each of the classes comprises a plurality of sample images, the image recognizing method comprising: generating an average image of each of the classes according to the sample images; generating a feature enhancement mask according to differences between the average images of the classes; enhancing the sample images of each of the classes by using the feature enhancement mask to generate a plurality of enhanced sample images corresponding to the class; training a classifier according to the enhanced sample images corresponding to each of the classes; enhancing the at least one testing image by using the feature enhancement mask to generate at least one enhanced testing image; classifying the at least one enhanced testing image into one of the classes by using the classifier; and recognizing that the at least one testing image belongs to the one of the classes.