A system and method for contactless blood pressure determination. The method includes: receiving a captured image sequence； determining, using a trained hemoglobin concentration (HC) changes machine learning model, bit values from a set of bitplanes in the captured image sequence that represent the HC changes of the subject； determining a blood flow data signal； extracting one or more domain knowledge signals associated with the determination of blood pressure； building a trained blood pressure machine learning model with a blood pressure training set, the blood pressure training set including the blood flow data signal of the one or more predetermined ROIs and the one or more domain knowledge signals； determining, using the blood pressure machine learning model trained with a blood pressure training set, an estimation of blood pressure； and outputting the determination of blood pressure.
