J . -M . Deniel et al .: Radioprotection 2024 , 59 ( 3 ), 225 – 234 233
Fig . 11 . Zoom on four 99 pixel areas denoted ( a ) to ( d ) in the 1100 ° C furnace picture ( top ). These areas are centered on the cross in the bottom pictures .
inter-reflections tend to make light spectral distribution even over the visible to NIR infrared wavelength range . In pictures , materials may appear as grey bodies , which corresponds the most to graphite . This hypothesis could be tested using the multispectral radiosity method ( Cohen et al ., 1998 ).
Our second remark is that irradiance estimated from picture analysis will have to account for
* the increased emissivity of metals with temperature ( Watanabe et al ., 2003 ; Touloukian et al ., 1970 ),
* a decrease of emissivity when water leaves porous materials , then an increase with temperature as we could measure it .
To account for these potential changes in the emissivities we measured , it will reasonable to increase the calculated irradiance by þ 20 %.
5 Conclusion
We propose a method to estimates irradiance from incandescent opaque materials on [ 780 ; 3000 nm ] by analyzing color pictures . The first principle in the method is estimating the temperature and the emissivity of incandescent materials from pixels color . Our results show that temperature estimations are consistent with that of observed sources , a blackbody as well as a furnace .
This method requires a kind of device several to tens of times less expensive than a radiometer or a spectroradiometer . In reality , such a device – a smartphone – is already present in the pocket of every preventer and makes our method virtually free .
To make this method genuinely usable in industry , several perspectives on the principle presented in this paper are planned .
The camera requires an easy and cheap calibration method . This is currently under investigation .
It must be usable with sensors having a low dynamic range , for example through the use of bracketing techniques ( Debevec et al ., 2023 ). This will also solve the problem with the method neglecting the darkest areas in the picture although they correspond to incandescent materials .
In a second paper , we will explain how to exploit these temperature and emissivity estimations , to prevent from cataracts in various industrial sectors .
Funding This research did not receive any specific funding .
Conflicts of Interest The author declares that he has no conflict of interest .
Data availability statement
The data that support the findings of this study are openly available in Open Science Framework ( OSF ) at https :// osf . io , under : - reference DOI 10.17605 / OSF . IO / VGFWK and - data public link .
Ethics approval Ethical approval was not required .
Informed consent This article does not contain any studies involving human subjects .
References
Avantes . 2020a . AvaSpec-NIR256 / 512-1.7-EVO – Avantes . 2020 . https :// www . avantes . com / products / spectrometers / nirline / avas pec-nir256-512-1-7-evo /.
Avantes . 2020b . AvaSpec-ULS2048XL-EVO . Avantes . 2020 . https :// www . avantes . com / products / spectrometers / sensline / avaspeculs2048xl-evo /.
Barlier A . 1994 . Rayonnements optiquesdans une forge – mesures et moyens de protection . Cahier Des Notes Documentaires 155 : 181 – 93 .
Barlier A , Salsi S . 1995 . Rayonnement infrarouge et cataracte -evaluation des risques a proximite d ’ un four a induction . Cahier Des Notes Documentaires 161 : 469 – 75 .