4.1 Electron imaging for camouflage textile assessment in grey scale imaging versus chromatic intensity
SEM image of uncoated PA-6,6 (a2); NSSD-FM-01 coated PA-6,6 fabric (b2); NSSD-FM-02 coated PA-6,6 fabric (c2); five time post washed NSSD-FM-02 coated PA-6,6 fabric (d2); uncoated cotton fabric (a5); NSSD-FM1 coated cotton fabric (b5); NSSD-FM-02 coated cotton fabric (c5) and five time post washed NSSD-FM-02 coated PA-6,6 fabric (d5); red color thresholding of SEM image of uncoated PA-6,6 (a1); red color thresholding of SEM image of NSSD-FM-01 coated PA-6,6 fabric (b1); red color thresholding of SEM image of NSSD-FM-02 coated PA-6,6 fabric (c1); red color thresholding of SEM image of five time post washed NSSD-FM-02 coated PA-6,6 fabric (d1); red color thresholding of SEM image of uncoated cotton fabric (a4); red color thresholding of SEM image of NSSD-FM-01 coated cotton fabric (b4); red color thresholding of SEM image of NSSD-FM-02 coated cotton fabric (c4) and red color thresholding of SEM image of five time post washed NSSD-FM-02 coated PA-6,6 fabric (d4); grey value intensity of SEM image of uncoated PA-6,6 (a1); grey value intensity of SEM image of NSSD-FM-01 coated PA-6,6 fabric (b1); grey value intensity of SEM image of NSSD-FM-02 coated PA-6,6 fabric (c1); grey value intensity of SEM image of five time post washed NSSD-FM-02 coated PA-6,6 fabric (d1); grey value intensity of SEM image of uncoated cotton fabric (a4); grey value intensity of SEM image of NSSD-FM-01 coated cotton fabric (b4); grey value intensity of SEM image of NSSD-FM-02 coated cotton fabric (c4) and grey value intensity of SEM image of five time post washed NSSD-FM-02 coated cotton fabric (d4).
Figure 4b1, 4b2, 4b4, 4b5; a well cementing has been demonstrated without cracking mark for both PA-6,6 and cotton fabric surface which may decline the breathability of fabric but there is possibility of NSSD reflection of chromatic matching against surrounding CB materials of desertland. SEM image of NSSD coated PA-6,6 fabric is comparatively lighter than SEM image of NSSD coated cotton fabric due to high reflection of PA-6,6 base surface related to polymeric structure of -NH2 group. Figure 4a1, 4a2, 4a4, 4a5, 4a3, 4a6 defines the comparison between the electron imaging of PA-6,6 and cotton fabric. PA-6,6 fabric has circular cross section than cotton surface. Hence, PA-6,6 fabric may have chromatic reflection at different angle [37]. SEM image of raw cotton image shows comparatively darker than raw PA-6,6 fabric because of chromatic deviation of base fabric. Cotton fabric has cellulosic structure related to existing -OH group. Oppositely PA-6,6 fabric has polymeric structure of -NH2 group. There is deviation of chromatic intensity between -OH group and -NH2 group. The presence of NSSD has been observed after five time washing shown in Fig. 4d1, 4d2, 4d4, 4d5. RGB red color thresholding has been remarked in Fig. 4a1, 4b1, 4c1, 4d1, 4a4, 4b4, 4c4, 4d4 for clarification and comparison of lightness and darkness hue of NSSD coated and uncoated PA-6,6; and cotton fabric. These evidences may clarify the exact bonding and chromatic aberration between NSSD uncoated and coated PA-6,6; and cotton fabric surface. Grey value intensities have also been presented in Fig. 4a3, 4b3, 4c3, 4d3, 4a6, 4b6, 4c6, 4d6 for clarification and comparison of lightness and darkness hue of NSSD coated and uncoated PA-6,6; and cotton fabric under selected pixels of SEM images. In general, NSSD coated and uncoated cotton fabric tends to lower intensity compared to NSSD coated and uncoated PA-6,6 fabric. Raw PA-6,6 fabric and cotton fabric shows lower grey value intensity rather than NSSD coated fabric. The lower grey values of raw PA-6,6 fabric and cotton fabric are 116 and 92, cited in Fig. 4a3. The higher grey values of raw PA-6,6 fabric and cotton fabric are 122 and 135, cited in Fig. 4a4. The lower grey values of NSSD coated PA-6,6 fabric are 152, 129, 95 and the higher grey values of NSSD coated PA-6,6 fabric are 158, 134, 160, mentioned in Fig. 4b3, 4c3, 4d3. Similarly, the lower grey values of NSSD coated cotton fabric are 117, 100, 100 and the higher grey values of NSSD coated cotton fabric are 122, 170, 120, mentioned in Fig. 4b3, 4c3, 4d3. Therefore, NSSD formulated fabric may be proceeded for target application of camouflage textile in terms of reflection matching/chromatic matching against desertland CB.
4.2 Chromatic assessment of CIE L*, a*, b* value for camouflage textiles against desertland CB
Figure 5, CIE L* value of NSSD coated PA-6,6 (60.49) and cotton fabric (67.49) have been found almost nearest of raw NSSD material (57.3) denoted as desertland CB although L* value of NSSD coated PA-6,6 and cotton fabric increases after washing compared to white and black standard. Similarly, CIE a* and CIE b* value of PA-6,6 (2.57 and 15.3) and cotton coated fabric (2.6 and 15.26) were also found nearest value compared with raw NSSD material (a* = 4.76, b* = 17.1). Hence, CIE L*, a*, b* value of NSSD coated fabric has been found chromatic matching against desertland CB. Uncoated PA-6,6 (89.64) and cotton fabric (93.04) shows the highest value of CIE L* and lowest value of CIE a* (-0.53, 3.59) and CIE b* (1.75, -8.95) compared to standardized white and black; and coated PA-6,6 and cotton fabric. The supporting information of CIE L*, a*, b* has been attached in Table SI 2.
4.3 Chromatic assessment of reflection (%) for formulated camouflage textiles against desertland combat background
Figure 6, a nearest graphical state of reflection (%) has been found for NSSD coated PA-6,6 and NSSD coated cotton fabric against desertland CB. The reflection (%) of FM-01 and FM-02 coated PA-6,6 and cotton fabric has also been found minor variation before washing and after washing against desertland CB. Hence, a symmetric reflection (%) has been investigated for FM-2 formulated PA-6,6 fabric (18–46)% and FM-2 formulated cotton fabric (23–46)% against desrtland CB (11–33)% when the graphical state of reflection was also noted and compared for untreated PA-6,6 fabric (75)%, untreated cotton (31–100)%, black standard 0% and white standard (81–86)% [38]. The supporting information of reflection (%) has also been attached in Table SI 3.
4.4 Chromatic assessment of K-M reflection for formulated camouflage textiles against desertland combat background
Figure 7, partially it may be argued that K-M reflection state is the opposite nature of reflection (%), referred to the graphical state of chromatic property assessment shown in Fig. 6. The existing percentage of NSSD on fabric surface is related to the alternate reflection property referred to the Fig. 2 and Fig. 4. Higher K-M reflection signifies the maximum existence of NSSD material on fabric surface which can be compared and sequenced as raw NSSD, desertland CB > NSSD coated PA-6,6 fabric, FM-2 > NSSD coated PA-6,6 fabric, FM-2, post washing > NSSD coated cotton fabric, FM-2 > NSSD coated cotton fabric, FM-2, post washing > NSSD coated cotton fabric, FM-01 > NSSD coated PA-6,6 fabric, FM-1 > NSSD coated PA-6,6 fabric, FM-1, post washing > NSSD coated cotton fabric, FM-01, post washing > untreated PA-6,6 > untreated cotton. The imbrication plot of K-M reflection has been observed for NSSD coated PA-6,6 fabric, FM-2, post washing; NSSD coated cotton fabric, FM-2 and NSSD coated cotton fabric, FM-2, post washing. Similarly, the overlapping plot of K-M reflection-FM-01 was also investigated for NSSD coated cotton fabric, FM-01; NSSD coated PA-6,6 fabric, FM-1; NSSD coated PA-6,6 fabric, FM-1, post washing; NSSD coated cotton fabric, FM-01, post washing. There is also similar K-M reflection among untreated PA-6,6; untreated cotton and white standard referred to Fig. 3. This explanation of K-M reflection is also supported by electron imaging in terms of existing NSSD on fabric surface shown in Fig. 4. The supporting information of K-M reflection has also been attached in Table SI 4.
4.5 Chromatic assessment of color rendering image for formulated camouflage textiles against desertland combat background
RGB-color rendering of NSSD coated cotton fabric, FM-02; RGB-color rendering of NSSD coated PA-6,6 fabric, FM-02; RGB-color rendering of NSSD coated cotton fabric after five-time post washing, FM-02; RGB-color rendering of NSSD coated PA-6,6 fabric after five-time post washing, FM-02 have been exposed sequentially in Fig. 8a, 8b, 8c, 8d. Figure 8a, 8b; RGB Khaki shading was generated by the image of color rendering in Vis wavelength. Figure 8c, 8d; RGB light shading of khaki was also showed after five-time washing.
Similarly; CIE RGB, L*, a*, b* chromatic hues of RGB color rendering images have been presented in Fig. 8a1-8d6.
4.6 Field trialling (phase 1–4) of coated and printed fabric/garment against multidimensional CBs under Vis imaging
4.6.1 Field trialling phase-01 for camouflage textiles against woodland CB, Shorea Robusta Gaertin
Figure 9a1, 9a2, 9a3 shows the raw image of digital RGB imaging. Figure 9b1, 9b2, 9b3 individually shows the CIE L* chromatic hue of RGB raw image. Figure 9c1, 9c2, 9c3 denotes the a* stack of digital image. Figure 9d1, 9d2, 9d3 signifies the b* chromatic hue of raw image. Figure 9e1, 9e2, 9e3 are the reddish tone of woodland CB. Figure 9f1, 9f2, 9f3 clarifies the greenish tone against woodland CB. Figure 9g1, 9g2, 9g3 reflects bluish tone of raw image, captured against woodland CB.
In Fig. 9a2, 9a3, RGB image; a nearest chromatic hue of NSSD coated and printed part has been pictured against woodland CB. CIE L* image of NSSD coated and printed part shown in Fig. 9b2, 9b3; CIE a* image of NSSD coated and printed part shown in Fig. 9c2, 9c3; CIE b* image of NSSD coated and printed part shown in Fig. 9d2, 9d3; red stack image of NSSD coated and printed part shown in Fig. 9e2, 9e3; green stack image of NSSD coated and printed part shown in Fig. 9f2, 9f3 and blue stack image of NSSD coated and printed part shown in Fig. 9g2, 9g3 appearances blending with background and signified camouflage against wooden bridge, woodland CB and concrete CB due to photonic response to the digital camera sensor relates to lower reflection and higher K-M reflection of NSSD coated and printed fabric, also shown in Figs. 6 and 7.
4.6.2 Field trialling phase-02 for camouflage textiles against woodland CB, Eucalyptus Citriodora, Bamboo Vulgaris; and concrete CB
Figure 10a1, 10a2 are the raw image of digital RGB imaging; Fig. 10b1, 10b2 shows the red chromatic hue against wooden bridge and Bamboo Vulgaris, woodland CB; Fig. 10c1, 10c2 are the green chromatic hue against woodland CB; Fig. 10d1, 10d2 are the blue chromatic hue against woodland CB; Fig. 10e1 and 10e2 are the CIE L* chromatic hue against woodland CB; Fig. 10f1 and 10f2 are the CIE a* chromatic hue against woodland CB; Fig. 10g1 and 10g2 are the CIE b* chromatic hue against woodland CB.
Figure 10a1, 10a2; the RGB image of coated and printed part looks blending against wooden bridge made by the combination of Eucalyptus Citriodora, Bamboo Vulgaris; Musa Acuminata and some unknown species of woodland CB; and a concrete road of concrete CB. Figure 10b1 and 10b2, red stack image; Fig. 10c1 and 10c2, green stack image; Fig. 10d1 and 10d2, blue stack image; Fig. 10e1 and 10e2, CIE L* stack image; Fig. 10f1 and 10f2, CIE a* stack image and Fig. 10g1 and 10g2, CIE b* stack image looks camouflage against wooden bridge, woodland and concrete CB due to response of digital camera sensor relates to lower reflection and higher K-M reflection of NSSD coated fabric, also cited in Figs. 6 and 7.
4.6.3 Field trialling Phase-03 for camouflage textiles against desertland CB
Figure 11a1, 11a2, 11a3, 11a4 are the raw image of digital RGB imaging; Fig. 11b1, 11b2, 11b3, 11b4 are the red chromatic hue against desertland CB. Figure 11c1, 11c2, 11c3, 11c4 are the green chromatic hue against desertland CB. Figure 11d1, 11d2, 11d3, 11d4 are the blue chromatic hue against desertland CB.
Figure 12a1, 12a2, 12a3, 12a4 are the raw image of digital RGB imaging; Fig. 12b1, 12b2, 12b3, 12b4 are the red chromatic hue against desertland CB. Figure 12c1, 12c2, 12c3, 12c4 are the green chromatic hue against desertland CB. Figure 12d1, 12d2, 12d3, 12d4 are the blue chromatic hue against desertland CB.
Considering RGB image, CIE L*, a* and b* of NSSD coated and printed part shows camouflage against desertland CB which are sequentially shown in Fig. 12a1, 12a2, 12a3, 12a4; Fig. 12b1, 12b2, 12b3, 12b4; Fig. 12c1, 12c2, 12c3, 12c4; Fig. 12d1, 12d2, 12d3, 12d4. Standardized white part of garment and white color of sky background looks bluish hue against desertland CB shown in Fig. 12d1, 12d2, 12d3, 12d4.
4.6.4 Field trialling phase-04 for camouflage textiles against simultaneous CB of rockland and water/marine
Figure 13a1, 13a2 are the raw image of digital RGB imaging; Fig. 13b1, 13b2 shows the red chromatic hue against rockland and water CB. Figure 13c1, 13c2 are the green chromatic hue against simultaneous CB of rockland and water. Figure 13d1, 13d2 are the blue chromatic hue against rockland and water CB. Figure 13e1, 13e2 are the L* chromatic hue against rockland and water CB. Figure 13f1, 13f2 are the a* chromatic hue against rockland and water CB. Figure 13g1, 13g2 are the b* chromatic hue against rockland and water CB.
Under the chromatic assessment of coated and printed part of garment; RGB image, Fig. 13a1 and 13a2; red stack of RGB image, Fig. 13b1 and 13b2; green stack of RGB image, Fig. 13c1 and 13c2; blue stack of RGB image, Fig. 13d1 and 13d2; and CIE L* stack of RGB image, Fig. 13e1 and 13e2; looks completely blending against rockland and sandy river water when compared with standardized white part of garment. CIE a* stack of RGB image in Fig. 13f1 and 13f2 shows blurred and intermingled image against rockland and sandy river water. CIE b* stack of RGB image in Fig. 13g1 and 13g2 also signifies camouflage of coated and printed part of garment against CBs of rockland and water/marine. Due to discrepancy of refractive index of water and rock at different temperature in Vis wavelength, the chromatic saturation of red, green, blue, L*, a*, b* may be altered for seasonal and sky background variation because of chromatic blending with sky background [39, 40].