One of the main differences between the C8 and C7 is the enhanced processing capability on the C8 which allows the C8 to utilize more sophisticated picture quality enhancement techniques in comparison to the C7 in addition to running the AI (Artificial Intelligence) ThinQ system for providing intelligent voice control not only for the TV but also for controlling other compatible smart devices. Furthermore, only the C8 supports 4K content with High Frame Rate (up to 120 fps) but only via USB. Unlike the C7, the C8 is able to perform a Black Frame insertion (which intends to reduce the sample-and-hold induced motion blur). The C8 has certain calibration related features (such as providing direct access to the TV’s internal look-up tables to a specialized software that is sold separately).
1. Different processor (Alpha 9 vs M16P)
The C8 is equipped with the new Alpha 9 processor. As a result, the CPU performance on the C8 is improved by up 35% in comparison to the C7’s M16P SoC (system on chip), according to LG. The GPU performance is also enhanced by up to 35% on the C8 vs C7. Another area of significant improvement for the C8 when compared to C7 is memory. All these enhancements combined are the root cause for most of the remaining differences between the C8 and C7.
2. Difference in the peak brightness
Although not related to the increased processing power on the C8 vs C7, it should be mentioned that the peak brightness on the C8 is slightly higher in comparison to the C7. Thanks to the Ultra Luminance Pro technology and some adjustments to the ABL (Auto Brightness Limiter), the brightness headroom is somewhat increased on the C8 vs C7. That being said, the C7’s standard Ultra Luminance technology and the absence of ABL up until about 150cd/m2 on a full-field white (100% APL) means that even the C7 provides adequate headroom for making the overall image brighter in case of watching high-APL content under high ambient light conditions, for example. The C8 is able to render small specular highlights in HDR content slightly brighter than the C7 although tone-mapping cannot be completely avoided, even for HDR10 content that has been mastered to 1,000cd/m2, unless you’re using significantly colder color temperature.
3. HFR (High Frame rate) capabilities on the C8
The HEVC decoder on the C8 conforms to the Main10 Profile at level 5.2 while the C7’s HEVC decoder is for Main10 Profile at level 5.1. The Level 5.2 support allows the C8 to decode HEVC files up to 3840×2160 at 120fps (maximum bitrate 60Mbps), whereas the 5.1 level support leads to the C7 being limited to decoding HEVC files up to 3840×2160 @ 60fps. Therefore, the C8 supports HFR (High Frame Rate) content albeit only via USB because it cannot accept 4K HFR signal via HDMI due to the lack of any HDMI 2.1 ports which are required for transmitting 4K 120fps signal (the HDMI 2.0b inputs on the C8 don’t have sufficient bandwidth for carrying 4K @ 120fps).
4. Expanded Cube (3D) LUT (Look-up Table)
The panel used on both the C8 and C7 is capable of 10-bit color depth, meaning the two OLED TVs are able to show over a billion colors (“Billion Rich Colors” in LG terminology). In order to be able to calculate all these colors, the C7 utilizes 4,913 reference points in a 17x17x17 Cube LUT. The C8, on the other hand, employs a 33x33x33 Cube LUT so there are 35,937 reference points used for calculating all 1.07 billion colors. The approximately seven fold increase in the number of reference points reduces the number of calculations the C8 has to perform in comparison to the C7 in order to find the position of a certain color inside the cube that has no predefined reference point that can be looked up, thus there is less chance of any errors that may manifest themselves as color artifacts on the screen.
5. Auto calibration (C8 only)
The C8 provides direct access to its hardware LUT (Look-up tables) to the CalMAN software by SpectraCal (sold separately) for the purpose of auto calibration (some calibration equipment is also needed for taking measurements off the screen). There are 5 SDR picture presets (including Game mode) on the C8 that can be calibrated using this method. When it comes to HDR, there are 3 modes for Dolby Vision and 3 modes for other HDR formats such as HDR10 and HLG that can be used for auto calibrating. There is a dedicated Dolby Vision Game mode as well as HDR10 Game mode. In addition to the 3D (Cube) LUT, the CalMAN software can directly address a 1D LUT on the C8. This look-up table contains 1024 reference points, and it’s used for calibrating grayscale and gamma. The C8 is therefore able to perform all calculations related to lighting in a non-linear space, thus preserving shadow detail. The C7 also allocates more bits for the lower end of the grayscale (in accordance to the non-linear response of human eyes to light intensity) so that it can render near-black gradation in cleaner fashion. That being said, the C7 doesn’t provide direct access to its look-up tables, and cannot be auto calibrated.
6. Black frame insertion (C8 only)
The C8 is able to further improve the motion clarity than the C7 thanks to the black frame insertion feature. The reason being is that the C8 provides a break in the continuous light output which in turn allows the retinal persistence to be cleared so that a moving object doesn’t appear blurred across subsequent frames. It should be said, though, that a brightness reduction is possible in the event you engage the Motion Pro on the C8 which controls the black frame insertion. Due to the nature of this feature, you may also exhibit some flickering, depending on how susceptible to noticing you are.
7. Improved Image Noise reduction
The Alpha 9 chip on the C8 employs a 4-step process that involves temporal noise reduction as well as banding removal. The latter is particularly useful in case of watching lower bitrate content which may be prone to quantization errors that manifest themselves as posterisation artifacts on the screen.The MPEG Noise reduction setting on the C8 controls whether or not the TV will attempt to remove any contouring artifacts. In contrast, the C7 doesn’t apply the decontouring or the temporal noise reduction filters twice when the MPEG noise reduction is used, meaning the C7 relies on two step noise reduction process vs the quad-step on the C8. The depth enhancement on the C8 is object-based rather than edge-based one. For the sharpness enhancements, textures and edges on the C8 are separately analyzed and processed accordingly in order for edges to become sharper whereas textures remain clear.
8. WebOS 4.0 and AI (Artificial Intelligence) ThinQ
The C8 comes with the latest version of the webOS Smart TV system. Furthermore, the C8 is equipped with the AI ThinQ system that provides intelligent voice control, and unlike the C7, it allows the C8 to become the IoT hub for other connected smart devices. The C8 is also compatible with Amazon Alexa devices (sold separately).
The C8 and C7 have a table top stand made of aluminum but the form factor and the finish of the stand is different on the C8 vs C7. The front portion of the C8’s stand is significantly wider than the rear support column. The front portion is slightly curved so that the sound coming from the down-firing speakers can be directed towards you. The C7’s stand, on the other hand, has a front and a rear side of identical width, hence the smaller footprint in comparison to the C8’s stand. Another difference between the C8 and C7 is the color of the section where the electronics and inputs are located. The bottom half of the rear panel is white on the C7 whereas it’s dark gray on the C8.
10. Image retention/burn-in prevention features
The C8 has one additional feature under OLED Panel settings in comparison to the C7. It’s called “Logo Luminance Adjustment” which may be useful if you watch TV network broadcasts for long periods of time. Both the C8 and C7 have the Pixel Refresher feature which triggers an hour long (or more) compensation cycle that detects and corrects any irregularities in the voltage supplied to different areas of the panel, thus visible image retention can be cleared. However, you don’t normally have to use the Pixel Refresher because the two OLED TVs are configured to automatically run a shorter compensation cycle at predefined intervals of time. Unless a static image is displayed on the C8 or C7 for prolonged periods of time (e.g. they’re exclusively used as a computer monitor), the risk of permanent image burn-in is minimal.
Check availability and pricing on Amazon.com for the C8 in the 65-inch OLED65C8PUA and 55-inch OLED55C8PUA class, as well as the C7 in the 65-inch OLED65C7P and 55-inch OLED55C7P class (affiliate links).