1. A method for image automatic brightness detection, the method comprising: determining region of interest ROI candidates in an image; extracting features from each of the ROI candidates; selecting an optimum ROI candidate based on a weighted score of each of the ROI candidates by at least: queuing all the ROI candidates in descending order for each of the features, and determining a serial number of each of the ROI candidates in the queue as a score of the feature of the ROI candidate; and calculating the weighted score of each of the ROI candidates by multiplying the scores of the extracted features for each of the ROI candidates respectively by a predetermined weighting coefficient of the feature to obtain respective products and summing the products, wherein the ROI candidate with the smallest weighted score is selected as the optimum ROI; and calculating brightness value of the selected optimum ROI candidate as brightness feedback.