Device, system and method for generating a photoplethysmographic image carrying vital sign information of a subject

System as claimed in claim 8, wherein said illumination unit is configured to emit modulated light having a modulation frequency outside the frequency band of the subject's pulse, in particular above 200 BPM.

Method for generating a photoplethysmographic image carrying vital sign information of a subject, said method comprising:

• obtaining image data of a skin region of a subject in at least two different wavelength channels, said image data comprising two or more image frames acquired by detecting light transmitted through or reflected from the skin region over time, wherein said image data comprise wavelength-dependent reflection or transmission information in said at least two different wavelength channels,
• combining, per pixel or group of pixels and per time instant, image data values of said at least two different wavelength channels to obtain a time-variant pulse signal per pixel or group of pixels, wherein the image data values of said at least two different wavelength channels are combined as a weighted combination of temporally normalized wavelength channels or of the logarithm of wavelength channels, wherein the sum of the weights used for the combination is substantially zero, and
• generating a photoplethysmographic image from a property of the respective pulse signals in a time window including at least two image frames.