A method for monitoring a physiological parameter associated with a subject using a hand held device, the method comprising: capturing a video of a body part, in particular a fingertip, of a sample subject using the hand held device; obtaining by a processor a plurality of windows from the video, wherein each of the windows includes a predetermined number of frames; determining by the processor at least one quantized colour value for one or more colour models, for each frame in the plurality of windows; and determining by the processor consistency of the video by performing consistency analysis for a predetermined number of determinant windows from the plurality of windows, based on the at least one quantized colour value of each frame, wherein the consistency analysis is performed, in response to obtaining the predetermined number of the determinant windows, and wherein in particular the determining comprises assessing whether the at least one quantized colour value is in a predetermined range of quantized colour values, the consistency analysis being achieved based on the assessing; obtaining, by the processor, a plurality of sample photoplethysmographic features associated with the sample subject, from a sample PPG waveform based on the consistency analysis; selecting, by the processor, from among the plurality of sample PPG features, at least one relevant sample PPG feature associated with the physiological parameter, based on a ground truth value of the physiological parameter for the sample subject; and determining, by the processor, based on the at least one relevant sample PPG feature and the ground truth value of the physiological parameter, a mathematical model indicative of a correlation between the at least one relevant sample PPG feature and the physiological parameter, wherein the mathematical model is deployed for monitoring the physiological parameter in real time. capturing a video of a body part, in particular a fingertip, of a sample subject using the hand held device; obtaining by a processor a plurality of windows from the video, wherein each of the windows includes a predetermined number of frames; determining by the processor at least one quantized colour value for one or more colour models, for each frame in the plurality of windows; and determining by the processor consistency of the video by performing consistency analysis for a predetermined number of determinant windows from the plurality of windows, based on the at least one quantized colour value of each frame, wherein the consistency analysis is performed, in response to obtaining the predetermined number of the determinant windows, and wherein in particular the determining comprises assessing whether the at least one quantized colour value is in a predetermined range of quantized colour values, the consistency analysis being achieved based on the assessing; obtaining, by the processor, a plurality of sample photoplethysmographic features associated with the sample subject, from a sample PPG waveform based on the consistency analysis; selecting, by the processor, from among the plurality of sample PPG features, at least one relevant sample PPG feature associated with the physiological parameter, based on a ground truth value of the physiological parameter for the sample subject; and determining, by the processor, based on the at least one relevant sample PPG feature and the ground truth value of the physiological parameter, a mathematical model indicative of a correlation between the at least one relevant sample PPG feature and the physiological parameter, wherein the mathematical model is deployed for monitoring the physiological parameter in real time.