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Firebrandx
Level 8

TCL 65R625 scaling doesn't allow for nearest neighbor on integer resolutions:

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It took several months to go through the process of contacting TCL about this issue and getting a ticket escalated to their engineers, but here's the problem in a nutshell:

On the previous series (R615) in 'computer mode', any integer resolution of the native display image is properly upscaled via nearest neighbor, which is great for retro-gamers that want the absolute sharpest digital image as possible for various FPGA or OSSC solutions. So what's an example of nearest neighbor integer scaling? Lets take 1280x720p. If you multiply that by 3x, you get the native resolution of the TCL display (3840x2160). So ideally for retro-gaming this source resolution of 1280x720 is simply upscaled via nearest neighbor, which gives razor-sharp pixel edges. Retro-gamers LOVE this.

However when the R625 series came out, nearest neighbor upscaling was removed from computer mode (or any other mode for that matter), making for soft edges and rounded corners on pixels. This is very disappointing. So at any rate, after several months of back and forth from TCL on my ticket for this issues, they finally got back to me and stated the following:

"Start a case with Roku to influence them to change the scaling method back for the Reno builds."

Now I have no idea how to 'influence' Roku to do that, but I figured I might as well post here to get started. Who do I have to beg to see the light on why this is so important for retro-gamers? I'm only requesting this optional scaling for Computer Mode, or even better would be if Roku added a "Retro-Gamer" mode, where it's similar to "Game Mode" but includes nearest neighbor scaling for integer scales of the TCL native display resolution. Most specifically, 1280x720, and 1920x1080.

Much appreciated for your time on this, and if Roku doesn't read these posts, hopefully someone can put me in touch with someone from Roku that will listen to this request for a firmware update.

1 Solution

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Salvor
Level 8

Re: TCL 65R625 scaling doesn't allow for nearest neighbor on integer resolutions:

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When’s the last time you tested this? I can see the subpixels in my photos and I see no obvious signs of bicubic interpretation in 720p.
I’m using the latest Roku update from April that added a auto game-mode feature so it’s possible they did add address this problem, I am using computer mode btw.

The biggest problem is how they are handling 480p which looks like garbage because it can’t integer scale to 4K without back bars, instead we get pixel wobble with lots of blurring, ideally we could have a black bar “pixel perfect” mode or a fullscreen mode using something like the sharp bilinear filter which is popular with Retroarch.

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13 REPLIES 13\
the_blur
Level 8

Re: TCL 65R625 scaling doesn't allow for nearest neighbor on integer resolutions:

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I have a 43" TCL Roku TV that I use as a computer monitor and I am wondering the same thing.

Harvini
Level 11

Re: TCL 65R625 scaling doesn't allow for nearest neighbor on integer resolutions:

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Actually, through this post you have done the rest of the ROKU TV user community a great service.  From the dialog you report with the TCL engineers, it is obvious that they are only in charge of the hardware.  All internal operations are now controlled by the ROKU OS, and so ANY malfunctions of the sorts described in thread after thread in this forum can be laid directly at the feet of ROKU and no one else.

the_blur
Level 8

Re: TCL 65R625 scaling doesn't allow for nearest neighbor on integer resolutions:

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The most disappointing thing is that it will happily turn off filtering in 3840 x 2160 mode. All I want is for the TV to do less work than it is currently doing.

Salvor
Level 8

Re: TCL 65R625 scaling doesn't allow for nearest neighbor on integer resolutions:

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Are you sure it isn’t using NN scaling for 720 and 1080? I haven’t noticed any blur or oddities when using those but if I set my Switch to 480 everything  looks awful so it’s certainly not using NN there. I’ve had this TV for over a year and 1080 has always looked razor sharp to me on it

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Salvor
Level 8

Re: TCL 65R625 scaling doesn't allow for nearest neighbor on integer resolutions:

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I took some extreme closeups photos of Super Mario World being played on Switch at 1080p with the app’s pixel perfect setting on, to my eyes the pixels are being scaled faithfully with no bilinear blur or pixel wobble, 720p looks extremely similar if not identical but 480p exhibited hellish pixel wobble and blurring. 

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Firebrandx
Level 8

Re: TCL 65R625 scaling doesn't allow for nearest neighbor on integer resolutions:

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I absolutely confirmed everything is bicubic upscaled on the 65R625. Took extreme closeups at over 6000 pixels resolution. Every resolution merely gets a little sharper as you get closer to the native res of the display. So 1080p will look better than 720p, but going 1440p will look even sharper than 1080p.

So yes, I am quite certain about this. We even compared it to the 65R615, which did have NN scaling, and the difference was blatantly obvious.

 

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Salvor
Level 8

Re: TCL 65R625 scaling doesn't allow for nearest neighbor on integer resolutions:

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When’s the last time you tested this? I can see the subpixels in my photos and I see no obvious signs of bicubic interpretation in 720p.
I’m using the latest Roku update from April that added a auto game-mode feature so it’s possible they did add address this problem, I am using computer mode btw.

The biggest problem is how they are handling 480p which looks like garbage because it can’t integer scale to 4K without back bars, instead we get pixel wobble with lots of blurring, ideally we could have a black bar “pixel perfect” mode or a fullscreen mode using something like the sharp bilinear filter which is popular with Retroarch.

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Salvor
Level 8

Re: TCL 65R625 scaling doesn't allow for nearest neighbor on integer resolutions:

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Thinking about this more I realize the 480p issue I’m talking about shows signs that it is performing nearest neighbor scaling because the pixel wobble Is an example of what happens when the resolutions don’t match for a full screen integer scale but you force it anyway without using bilinear or bicubic filtering, Mario’s left eye is squished into a thin line of two half sized pixels, the back pixel outline on the title screen shifts from square pixels to rectangular ones.

To quote https://tanalin.com/en/articles/integer-scaling/ 

At fractional scales (e. g. 4.5 when scaling 640×480 to 4K), “Nearest Neighbour” leads to image distortionand so called pixel shimmering. This is due to different sizes of pixels in the same image: for example, at 150% scale, some pixels are 1×1, while others are 2×2, 2×1, and 1×2.

With integer-ratio scaling, the scale is always integer (e. g. exactly 4 in the 640×480→4K case) — regardless of the native-to-logical resolution ratio. The space that might be left empty due to nondivisibility of the resolutions is filled with black like in the “Center” mode.”

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Firebrandx
Level 8

Re: TCL 65R625 scaling doesn't allow for nearest neighbor on integer resolutions:

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I will check again today and report back. However, I seriously doubt they addressed this issue as I was completely blown off in my complaints. Miracles can happen, so I won't completely dismiss it and will check it out.

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