332 J-M Deniel : Radioprotection 2024 , 59 ( 4 ), 327 – 337
Table 3 . Picture definition effects on the sum of form factors and the irradiance estimation . Only p pixels corresponding to incandescent materials are considered here .
Definition |
|
|
|
Difference with 4,6403,472 px |
|
Width px |
Height px |
P p ff p sr |
E IR
W / m 2
|
D P p ff p |
D E IR |
4,640 |
3,472 |
0.049252 |
1,797 |
|
|
2,320 |
1,736 |
0.048445 |
1,753 |
�64 % |
�2.45 % |
1,160 |
868 |
0.047411 |
1,651 |
�3.74 % |
�8.12 % |
580 |
434 |
0.046856 |
1,614 |
�4.87 % |
�10.18 % |
290 |
271 |
0.046552 |
1,556 |
�5.48 % |
�13.41 % |
145 |
109 |
0.046557 |
1,587 |
�5.47 % |
�11.69 % |
73 |
55 |
0.047112 |
1,617 |
�4.35 % |
�10.02 % |
Fig . 6 . Top : pictures of our metal furnace with black line silhouettes in the highest and lowest resolutions tested in this paper . Bottom : estimated temperatures at various image resolution , in false colors .
We explored definition effects on exposure assessment through E IR difference and the sum of relevant pixel form factors sum in the picture of the 1,000 ° C furnace . We reduced picture definition from 4640347px down to 7355 px by powers of two using Gimp 2.10 software ( Spencer Kimball , Peter Mattis , 2021 and The Gnome Project , 2021 ) and bicubic interpolation ( Rowe , 2018 ).
The results are compared to those of the original picture in Table 3 . The difference in evolution between the sum of the form factors and irradiance seems mainly due to pixel color interpolation influencing T temperature and m material estimation .
3.4 Combined effect of picture definition and item silhouette on irradiance estimation
We studied definition effects on the irradiance estimation , in the case where incandescent objects are not massive areas of pixels in the picture . This may be the case of forged pieces for example . Again , we used the 4,6403,472px picture of our metal furnace at 1,000 ° C . Black lines were added to this picture to make its silhouette stand out more clearly , as illustrated in Figure 6 . In this figure , we show the method result in terms of temperature estimation at various image resolution .
Table 4 should be read like Table 3 , for the combined effects of silhouette and resolution . In both tables , a decrease in E IR and Sff p is observed ( R 2 ( Sff p ; E IR )= 0.82 ): as shown in Figure 6 , lower resolution images show dark areas compared to full resolution . Color of pixels in a lower resolution image comes from mixing that of a higher resolution image . Then , ( g p / r p ; b p / r p ) hue of these p pixels may not match any ( m p ; T p ) material and temperature in the hue-to-temperature and material precomputed matrix ( Deniel , 2024 ). In this case , these p pixels are ignored in the E IR evaluation . In other case , ( g p / r p ; b p / r p ) may correspond to ( m p ; T p ) different from the full