Capabilities of various VDPs at parallax effects

[iNCEPTIONAL]

The PCE has a high resolution mode that allows blending colors to move beyond its palette. The Genesis can also do this... on composite output on a TV that filters composite input. Blending colors really eats into detail, though, which is why having the high resolution mode on the PCE makes blending easier than on the Genesis. A number of Genesis games use blending for more color - you can see the dithering of the pixels meant to blend together in emulators or on good TVs, especially if you're not using composite video.

I just noticed you mentioned both the PCE and Genesis can do some kind of colour blending to move beyond their palettes, and in PCE's case by using the higher resolution (512x224), but what about the SNES which also has the likes of its 512x224 pseudo high-res and 512x224 high-res modes and even the 512x448i mode?

https://youtu.be/AnEuk8Vj3w0?si=w88CJ-WsDHu7fGVT&t=123

Would the same thing work there in some way to allow it to display even more colours on-screen than normal as you mentioned for the two other consoles?

[Chilly Willy]

Yes, the same thing would apply to the 512 wide mode of the SNES. But with 256 colors from a palette of 32768, it's not nearly as needed as the 16 colors of the MD and PCE.

[iNCEPTIONAL]

Good to know. Thanks.

Yeah, it makes sense that the SNES' default Mode 3/4 colour options are obviously already capable of great looking 8bpp 256-colour images. But I guess since the idea/exercise is to find ways to push as many colours and as high a resolution as can be achieved to get the most visually beautiful images possible from these systems, it would certainly be worth trying the same on SNES to see just what's possible there too when taking full advantage of either the Mode 3/4 8bpp 256 GCRAM colours, Mode 3/4 2048 direct colours plus 128 CGRAM colours, or Mode 5/6 4bpp 128 CGRAM colours in 512x224 resolution options.

There's lots of options to be explored, which I honestly don't think really have been for the most part. In fact, I have not personally seen a single example of an image that shows truly just how many colours maximum at what kind of max resolution the SNES can manage, or at least not beyond just some generic image of a colour palette or something totally uninspired like that. There's the one that supposedly shows all 32,768 colours on-screen at once, assuming it's not fake, but it's literally just an image of a large colour palette with no indication it can be used to actually show proper images. So that's something I'd love to see.

[turboxray]

The SNES using of 512 pixel mode doesn't blend well though. The composite artifacts, at least in NTSC.. leaves a lot of garbage artifacts (you can see it when SNES games using interleaved pixels for pseudo transparency via 512px mode over composite - it looks horrible). PCE doesn't have this issue; PCE doesn't have the composite artifacts and doesn't rely on it to make color blending (it's not generic composite encoder - it's done on a digital level inside the chip to maximize detail output - and then combined from three analog component signals externally into a CVBS circuit).

So the effect is literally just a low-pass filter effect against that res, rather than chroma-luma interference. Of course, over composite the Chroma (color) signal is also filtered down to even less res compared to the Luma channel, but doesn't have that much of an effect to be honest (my "simulation" mode in the app doesn't account for this and looks extremely close to the actual output).

In order to achieve the same affect on SNES, you'd have to make your own external low-pass filter to apply to svideo or RGB output for the 512px res. And given there isn't enough vram for high color and high res (512x224), you'd need to use the 4bpp mode on the SNES for 512px res.. and it limits you to 8 subpalettes. From a lot of my tests trying to make snes 512px images using 8 subpalettes... most of them exhibit a lot of attribute artifacts. Even the much larger 32k main palette doesn't help here (originally I thought it would). To the point where it's just better to use 256px res and 8bpp modes. PCE just about gets away with it due to 16 subpalettes for BG (and separate 16 for sprites).. even at that, 16 is touch on some images which need manual correction afterwards.

These are raw captures of PCE hires mode over its composite video:





Notice the absence of NTSC color artifacts. I've also view these images over TurboGrafx PAL, which has the same low-pass look. It's not completely filtered out though, as some high res detail does pull though. From my measurements, details in the high bandwidth range come through (i.e. up to 370px range can be seen).

You can see the rest here: https://twitter.com/turboxray/status/16 ... 4478017536
Note: These are old conversions. These didn't take into account the special VCE internal palette (which isn't actually RGB, but 9bit RGB is an index into a 15bit YUV table).. my conversion app has since been updated to better color match on the new palette, giving improved results both in detail and gradients.

[iNCEPTIONAL]

Until someone tries to truly push the SNES to output something beyond the 8bpp 256-colour 256x224-resolution images that are possible as standard in Modes 3 and 4 on the system, the following representative examples of stock-SNES-spec accurate images as they would be viewed in pixel perfect mode on a typical modern monitor are about as good as we're going to see (created using Rilden's Tiled palette Quantization tool):

8bpp 256-colour 2x scale.png (225.28 KiB) Viewed 21355 times

Here's an example of a screenshot from an actual SNES game with a lovely 8bpp title screen image (taken in Mesen-S):

Aero2 2x Scale.png (56.37 KiB) Viewed 21146 times

We clearly haven't seen anywhere near the best the SNES is capable of outputting with these high quality images though, especially given we still don't have any great examples of 8bpp 256-colour plus colour math and HDMA images, or 2048 direct colour plus 128-CGRAM-colour images, or 512x224 or possibly 512x448 resolution images with any kind of blending and the like, or even anything that actually tries to go beyond the standard built-in options for static images, and definitely not anything that shows how the stock SNES can also display all of these standard image options during actual gameplay too if so desired.

Not that most people wouldn't be totally happy with and indeed probably blown away by the quality of even the standard Mode 3/4 256x224 8bpp 256-colour representative images above, but maybe one day we will get to see what SNES is truly capable of in this area, with actual real limit-pushing viewable and even playable examples in some cases that everyone can appreciate, which I think will be very cool.

For now though, here are some additional representative mockups I made of what the stock SNES is basically be capable of with Mode 4's 8bpp images plus gameplay, give or take a couple of minor tweaks here and there, some of which I've already altered in my latest local versions to be even more accurate, but basically this:

https://www.youtube.com/watch?v=tqCj2Sa6l5Y

https://www.youtube.com/watch?v=_KKWVDbFUQ8

https://www.youtube.com/watch?v=1sDXq-tByfc

And here's a link that explains how I would maybe go about doing some of the stuff in my examples above for anyone who's curious:

https://inceptionalnews.wordpress.com/2 ... d-be-done/

Edit: Interestingly, here are a couple of example images that would be 512x224 and 4bpp with 16x8 tile size on SNES as best as I can represent them, which have been colour converted using Rilden's tiled palette quantization tool:

512x224 4bpp DitherDiag4and2.png (143.71 KiB) Viewed 20554 times

These images don't use any HDMA, colour math, pixel blending, composite signal manipulation, or anything like that either. It's also just the pure pixels as they again would be viewed on a typical modern monitor rather than how they might look when seen on a CRT that softens and blends the pixels more, where they would look even nicer. Rilden's tool isn't even properly setup for this also, as there's no true way to convert an image at 512x224 resolution that has pixels half as wide as they are high without making all the pixels the same aspect ratio again. So I literally had to use it with a vertically squashed 512x224 image, convert everything, and then change the size in Photoshop to 512x448 using nearest neighbour scaling to represent the pixels that are half as wide as they are high in 512x224 mode on SNES, which clearly isn't optimal.

So, yeah, I'd definitely like to see more of what can be done in this space.

[iNCEPTIONAL]

To get back to something more in line with the original topic, I was just curious if you are able to set the background tiles to high and low priority on Genesis, SNES and PC Engine, so you can move objects in front and behind different parts of a single background layer on a per-tile basis?

This was something I saw recently on this website:

https://rasterscroll.com/mdgraphics/gra ... scrolling/

Specifically the bit where it mentions "How does Mickey walk behind the tree? Priority for planes is set per-tile, so the tree tiles are set to high priority, while the rest of Plane A is set to low priority. Mickey’s sprites are set to low priority, so they pass behind the tree but in front of everything else."

So, I know you can do this on Genesis, which is kinda cool, and just want to check if you can similarly do it with the backgrounds on SNES and PC Engine?