This work is motivated by the fact that existing no-reference sharpness metrics fail in predicting the correct amount of blurriness in images with different contexts. This paper presents a no-reference objective sharpness metric that can be applied to images with different contexts. The metric combines a Human Visual System (HVS)-based sharpness perception model as well as a local features extractor resulting in a content-invariant metric. The proposed HVS-based sharpness perception model is derived from performed subjective tests. Simulation results and comparison with existing no-reference sharpness metrics show that the proposed HVS-based sharpness metric correlates well with the perceived sharpness and is able to correctly predict the relative amount of blurriness in images with different contexts.