What is the point of the pseudo hi-res mode?

[Ronian53]

Some games like Kirby Dreamland 3 use a psuedo hi res mode that makes the dithering on the layer high resolution to fake transparency. But why do this if the SNES has real transparency?

[tepples]

One difference I know is that pseudo-hires allows mixing 50% sub with 25% main and 25% COLDATA, or 75% sub with 25% main. Another difference that might (I'm not 100% sure) be relevant is limits on how sprites participate in color math, including which sprite palettes can and can't.

[Nikku4211]

Pseudo hi-res mode can also be used to get a 512px horizontal resolution in modes other than 5 or 6. It does require joining 2 layers, so you still might as well use modes 5 and 6, but at least you can get 2 2BPP layers with mode 0 if you want both layers' tileset graphics to take less space(which is important when your tiles have to be twice as wide in memory just to take the same amount of space in 512px horizontal resolution).

[LucianoTheWindowsFan]

The SNES has real transparency. It was the half mode of color math.

[93143]

No, Kirby and some other games used pseudo-hires to fake half transparency. The advantage is that while it uses up the subscreen the same as a real half blend, it doesn't use up the colour math hardware, so you can still do math with the constant colour in addition to the fake blend (which looks like a real blend on a period TV).

[Nikku4211]

No, Kirby and some other games used pseudo-hires to fake half transparency. The advantage is that while it uses up the subscreen the same as a real half blend, it doesn't use up the colour math hardware, so you can still do math with the constant colour in addition to the fake blend (which looks like a real blend on a period TV).

And would still look like a real blend even on a modern HDTV if you're still using composite or RF.

Not sure about S-Video, though.

[tepples]

On S-Video you can see the vertical stripes, which are 60% finer than the vertical stripes you already see in half of the Genesis library.