pi-camera response curves

OmniVision OV5647

In order to use the raspberry pi cameras within a more rigorous scientific framework (such as inverse modeling from PhenoPi data) I needed the full spectral response of the chipset used in these cameras, the OV5647 by OmniVision.

I set out to do acquire the response curves using a DIY diffraction grating approach. During this process I was contacted by Howard Shapiro who volunteered his old spectrofluorometer to accomplish this task faster and more precisely. Although, initial tests together with Howard showed promise, it would remain an arduous task to quantify the whole spectral response. Recently, Howard managed to dig up some documentation on the chipset which displayed the spectral response (quantum efficiency, QE) in a graph (given that the OmniBSI chipset as displayed is the one residing in the OV5647). This has made things considerably easier.

I used these slides to digitize the quantum efficiency of the OV5647 between 400 and 700 nm. A physical measurement will still be needed to quantify the remaining near infrared spectrum (> 700 nm).

Missing or uncertain edge values, at the beginning and end of each curve, were carried forward or backward when missing (2 values at most). Note that these values are scaled between 0-100% while the true QE peaks at an efficiency of 53.6% in the blue channels respectively. Relative amplitudes should be preserved, which matters most for applications using (bandpass) filters.

Sony IMX 219

More recent pi camera boards (v2) have a different chip on board. Similar to the OV5647 I digitized the spectral response from Sony IMX 219 spec sheets (mentioned in this forum thread).Ā Missing or uncertain edge values, at the beginning and end of each curve, were carried forward or backward when missing (2 values at most).quantum_efficiency_sony_imx219

You can download the spectral response curves for both Raspberry pi cameras HERE.