shows is possible (see Fig. 43 in § 3) Luminance signal is Clipping at black or white. The colour of low NCL equally to R, G, B frequency component 3 signals and the results changes. CL exceed the legal value. The luma signal Y' is Mixed results of two images The output colour image formed by applying the in the CL domain may not be appearances after the nonlinear function to the the same as those in the R'G'B' mixing operation is similar sum of linear RGB domain. in some cases and is 4 CL signals. Then, the CB'CR' partially different in other signals are produced by cases (see § 4.2). subtracting the Y' from the gamma-corrected B'R'. The impact of different signal formats of NCL and CL on a studio post production and a delivery process was examined since the WP 6C meeting in September, 2011. The evaluation results are very briefly described in Table 19. TABLE 19 Summary of the evaluation results for the NCL and CL video signal formats NCL-Y'CB'CR' CL-Y'CB'CR' (1) Mixing Similar output appearance Comparing the output – – operations compared with that in nonlinear appearances between the NCL R'G'B' domain and the CL domains, the results Natural images – can be summarized as follows: (see § 4.2) Overall darker output – appearance compared with that In some cases, output • in linear RGB domain appearance differences are visible in parts of the image, but not in the entire image. Studio In other cases, no significant • post- difference is observed. Overall darker output – appearance compared with that in linear RGB domain (2) Larger loss (i.e. smaller Compared with the NCL, less – – in the original loss (i.e. larger PSNR-lightness) operations luminance information in the original luminance (see § 4.1) down-sampling process than in information after the CL colour difference signals Beneficial to improve – compression efficiency due to Delivery using HEVC Codec more orthogonal CL video (see § 4.4) signals (see § 2.5) compared with the NCL signals References
shows is possible (see Fig. 43 in § 3) 3 NCL CL Luminance signal is equally to R, G, B signals and the results exceed the legal value. Clipping at black or white. The colour of low frequency component changes. 4 CL The luma signal Y' is formed by applying the nonlinear function to the sum of linear RGB signals. Then, the CB'CR' signals are produced by subtracting the Y' from the gamma-corrected B'R'. Mixed results of two images in the CL domain may not be the same as those in the R'G'B' domain. The output colour image appearances after the mixing operation is similar in some cases and is partially different in other cases (see § 4.2). The impact of different signal formats of NCL and CL on a studio post production and a delivery process was examined since the WP 6C meeting in September, 2011. The evaluation results are very briefly described in Table 19. TABLE 19 Summary of the evaluation results for the NCL and CL video signal formats NCL-Y'CB'CR' CL-Y'CB'CR' Studio post- (1) Mixing operations – Natural images (see § 4.2) – Similar output appearance compared with that in nonlinear R'G'B' domain – Overall darker output appearance compared with that in linear RGB domain – Comparing the output appearances between the NCL and the CL domains, the results can be summarized as follows: • In some cases, output appearance differences are visible in parts of the image, but not in the entire image. • In other cases, no significant difference is observed. – Overall darker output appearance compared with that in linear RGB domain (2) operations (see § 4.1) – Larger loss (i.e. smaller in the original luminance information down-sampling process than in the CL – Compared with the NCL, less loss (i.e. larger PSNR-lightness) in the original luminance information after colour difference signals Delivery using HEVC Codec (see § 4.4) – Beneficial to improve compression efficiency due to more orthogonal CL video signals (see § 2.5) compared with the NCL signals References