The B8 and C8 differ in their processing capabilities, picture enhancements techniques (mainly low bitrate content is affected, though), the number of color data points in their internal Cube (3D) LUTs (look-up tables), the screen sizes they comes in (only the C8 has a 77-inch class model).
1. Different processor (Alpha 7 vs Alpha 9)
The B8’s Alpha 7 chip has more limited processing capabilities in comparison to the C8’s Alpha 9 chip. As a result, the B8 only employs dual step instead of the quad step noise reduction on the C8. The internal Cube (3D) look-up table on the B8 has fewer color data points in comparison to the C8. There is a potential difference when it comes to processing HFR (High Frame Rate) content in conjunction with HDR (High Dynamic Range) but more on this in the next paragraph.
2. HFR (High Frame Rate) capabilities
Although both the B8 and C8 are equipped with a HEVC decoder conforming to the Main10 profile at Level 5.2, meaning the two OLED TVs can decode HEVC files up to 3840×2160 at 120 fps, it should be said that due to the lack of HDMI 2.1 ports on either B8 or C8, they cannot accept 4K HFR signal via HDMI. The reason being is that the bandwidth on the B8 and C8’s HDMI 2.0b ports in not sufficient for 4K@120fps. In other words, HFR content is supported only via USB on both the B8 and C8. Although the C8’s Alpha 9 chip currently doesn’t have any advantage over the B8’s Alpha 7 processor in terms of HFR, it should be said that according to LG the more limited processing power on the Alpha 7 chip results in the B8 being capable of either 4K HDR or 4K HFR (but not both) whereas the C8’s Alpha 9 processor is powerful enough for 4K HDR HFR content. It’s not clear, though, when such content may become available, and whether or not the C8’s internal streaming apps are compatible with 4K HDR HFR content (HDMI connection cannot be used due to the lack of sufficient bandwidth).
3. Different Cube (3D) LUT (Look-up table)
The B8 employs a 17x17x17 Cube (3D) Look-up table whereas the C8 uses a 33x33x33 Cube (3D) LUT. This translates to 4,913 color data points on the B8 vs 35,937 color data points on the C8. Considering these data points are used as a reference when the TV calculates the position of any of the 1.07 billion colors on the B8 or the C8 that cannot be directly looked up, the C8 has an advantage in terms of the color accuracy, which is made evident by the fact that the True Color Accuracy Pro is present on the C8 while the B8 has the standard True Color Accuracy. Although both the B8 and C8 provide a direct access to their Cube LUTs to the CalMAN software by SpectraCal (sold separately), not all reference points are individually auto-calibrated (not least because the amount of time it would take for all measurements to be completed, even with the B8’s 17x17x17 Cube LUT). Nevertheless, the C8’s enhanced Cube LUT in comparison to the B8 makes it less likely for any errors in color calculations to occur. The B8 and C8 also provide the CalMAN software with a direct access to their 1D LUT which contains 1024 data reference points on both TVs, and is intended for calibrating grayscale and gamma.
4. Difference in the noise reduction and picture enhancements
The C8 utilizes a quad step noise reduction process in which two of the steps are intended to smoothen out the gradation (by removing any banding caused by quantization errors that low bitrate content is prone to). In contrast, the decountouring and temporal noise reduction filters are not applied twice on the B8 which makes it less effective in removing posterisation artifacts with low bitrate content, for example. The C8 is equipped with Object Depth Enhancer so that it can clearly separate an object from the background. The Frequency-based Sharpness Enhancer on the C8 allows edges and textures to be separately analyzed and processed accordingly so that not only the sharpness of the edges is boosted, but so are fine details in textures.