Wednesday, January 20, 2021


The main difference between the LG BX vs CX and GX is due to the picture processor and the image enhancements it can perform, rather than any fundamental difference in the picture quality which is comparable between the LG BX, CX and GX (apart from the BX having slightly lower brightness output in comparison to the LG CX and GX).

Display Type and Resolution WRGB OLED with 4K (3840x2160) resolution
Color bit depth 10-bit; "Billion Rich Colors"
Picture Processor α7 Gen 3 Processor 4K α9 Gen 3 AI Processor 4K
Noise Reduction Process Double Step Quad Step
Smooth Gradation 1 pass 2 passes
Sharpness Enhancer Yes Yes (Frequency-based)
Resolution Upscaler 4K Upscaler AI Upscaling
Color Accuracy True Color Accuracy True Color Accuracy Pro
3D LUT Size 17x17x17 33x33x33
1D LUT Size 1024 entries; 15-bit precision
AI Brightness Control Yes
AI Picture Yes Yes; Pro
Auto Genre Selection Yes, (Dolby Vision only) Yes (SDR, HDR10, Dolby Vision)
AI Sound Yes Yes; Pro
Up-mix Virtual 4.0-ch Virtual 5.1-ch
Adaptive Sound Control Yes
AI Acoustic Tuning Yes
Speaker System 2.2-channel 4.2-channel
Audio Output Power 40 Watts (20W woofer) 60 Watts (20W woofer)
HDMI ports 4 (2 HDMI 2.1 + 2 HDMI 2.0) 4 (HDMI 2.1)
TV stand Yes (plastic) Yes (metal) Not included, optional
Wall-mount bracket Not included Yes: Flush Wall Mount (WB20GB)
VESA VESA 300x200 Compatible (77": VESA 400x200) VESA 300x300 Compatible

The difference between the picture processor used by the LG BX and the one that the LG CX and GX have is mainly evident with low quality content because the Alpha 9 Gen.3 processor is able to more effectively remove in-source posterization artifacts (in case the bit rate of the content is too low which causes quantization errors) due to the the smooth gradation filters being applied in two passes (vs single pass on the Alpha 7 Gen.3 processor).

Considering that even High Definition content can be overly compressed (in order for less bandwidth to be used during streaming, for example), the 2-pass Smooth Gradation is arguably one of the more meaningful advantages that the LG CX and GX have over the BX. Since the entire process on the LG CX and GX is quad-step, the two OLED TVs also perform noise reduction in two passes (in addition to the aforementioned 2-pass smooth gradation). The Smooth Gradation is done independently from the noise reduction, meaning that banding removal doesn't cause any loss of fine detail. The same applies to the BX as well, except that there is only a single pass of noise reduction and smooth gradation (for a two step process).

While the frequency-based sharpness enhancer provides the CX and GX with a slight advantage over the BX, it should be said that accentuating an object's edges is rarely needed unless the upscaling of low resolution content produces overly soft image.

The advantage of the AI Upscaling used by the LG CX and GX over the LG BX's 4K Upscaler is that the deep-learning algorithm may yield improved results over time but this is relevant only for low resolution content such as SD (standard definition).

The LG CX and GX have True Color Accuracy Pro because of their Cube 3D LUTs (Look-up Tables) size which is 33x33x33, meaning they contain 35,937 entries. The BX, on the other hand, utilizes 17x17x17 Cube 3D LUT so it relies on 4,913 color reference values for performing direct color corrections as well as color interpolation. The bigger 3D LUT size is prerequisite not only for achieving more accurate colors out-of-the-box, but also for being less error-prone during calculations of any colors without a direct correction value. All three LG OLED TVs support auto-calibration via the CalMAN Software (sold separately) which can directly access their 1D and 3D LUTs. While there are different profiling algorithms for evaluating their color rendering and (generating 3D LUT) you can choose from in the CalMAN software, it should be said that not all of 35,937 color correction entries that the LG CX and GX can store are measured (for example, the Intelligent Resolution Profile supports up to 10,000 measurements). With the Lightning LUT or Matrix LUT algorithms the difference between the Cube 3D LUT size on the BX vs CX and GX is even less relevant (due to the fewer measurements). Nevertheless, the point of the CX and GX having to perform less color interpolation (thus being less prone to errors in color calculations) in comparison to the BX still stands.

While all three LG OLED TVs utilize a deep-learning algorithm in order to determine the quality of the content and provide the needed enhancements, it should be said the the LG CX and GX have the AI Picture Pro technology (a database containing more than a million visual data points has been used for its development) whereas the BX relies on the standard AI Picture. The Auto Genre Selection on the BX is limited to only Dolby Vision HDR content while on the the CX and GX it can also be used for SDR and HDR10 content, meaning the latter two LG OLED TVs are able to recognise a wider range of movies, sports, animation films, and have the picture and sound automatically adjusted for the specific genre.

The AI Sound Pro found on the LG CX and GX uses a deep-learning algorithm that has been developed from over 17 million sound data points, meaning the CX and GX have an advantage over the BX (which uses the standard AI Sound) when it comes to identifying voices, sound effects and different frequencies so that they can provide optimizations accordingly.

Another difference is that the BX is able to up-mix 2-channel sound to a Virtual 4.0 channel whereas the CX and GX: up to a Virtual 5.1-channel. All three LG OLED TVs have Adaptive Sound Control and AI Acoustic Tuning. The latter equalizes the TV speakers based on the acoustics of your room by using the build-in microphone in the Magic Remote.

The LG BX and GX series have down-firing speakers whereas the CX, due to the form of its table-top stand which acts as a reflector, is able to direct sound towards the front of the TV. Therefore, the LG CX has a slight advantage in terms of sound clarity provided it's placed on the table-top stand. The speaker system is 2.2-channel on the BX and CX, and 4.2-channel on the GX. They all allocate 20 Watts to the subwoofers, and 10 Watts per channel for the speakers, so in case of the BX and CX the total audio power output is 40 Watts, and 60 Watts on the GX.

Since the LG GX is designed to be mounted on a wall, there is only a Flush Wall Mount (WB20GB) included with the TV and no table-top stand (although it can be purchased separately). Conversely, the LG BX and CX come with a table-top stand but no wall-mount bracket. The LG BX and CX are VESA 300x200 compatible except for the 77-inch class which is VESA 400x200 compatible. The LG GX is also VESA 300x300 compatible.

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