How to do Semantic Segmentation using Deep learning

Unlike classification where the end result of the very deep network is the only important thing, semantic segmentation not only requires discrimination at pixel level but also a mechanism to project the discriminative features learnt at different stages of the encoder onto the pixel space. Different approaches employ different mechanisms as a part of the decoding mechanism. Let's explore the 3 main approaches: The region-based methods generally follow the "segmentation using recognition" pipeline, which first extracts free-form regions from an image and describes them, followed by region-based classification. At test time, the region-based predictions are transformed to pixel predictions, usually by labeling a pixel according to the highest scoring region that contains it. R-CNN (Regions with CNN feature) is one representative work for the region-based methods.