RGB565 to HAM8 RGB666

[BSzili]

I'd like to display a 16-bit RGB565 chunky image on a HAM8 screen. I found a C2P routine which works nicely, but it only produces an RGB555 bitmap, so the brightness is halved:
https://github.com/Kalmalyzer/kalms-...rgb555h8_040.s
I'm wondering if it'd be possible to modify this routine to produce an RGB666 bitmap instead

[robinsonb5]

Wouldn't it be much easier to shuffle the bitplane pointers so you move plane 5 -> plane 6, etc, making the blank plane the least significant rather than most significant?

[BSzili]

D'oh, thanks for the tip! I didn't even think of that I tried it and it looks fine, white comes out as (248,248,248) which works for me

[Karlos]

Id love to see what you're doing with it.

[BSzili]

A sneak peak:

[Karlos]

Doom RPG?

[pipper]

Wouldn't it be much easier to shuffle the bitplane pointers so you move plane 5 -> plane 6, etc, making the blank plane the least significant rather than most significant?

You could even go one step further and make it so that the screen is reusing the same bitplane for bit 0 and 1.

[Dunny]

Originally Posted by pipper

You could even go one step further and make it so that the screen is reusing the same bitplane for bit 0 and 1.

I was wondering about that. By bumping up by one bitplane you're effectively doubling the brightness of each pixel, which would render intentionally dark pixels lighter than intended?

[BSzili]

Not quite, bumping the bitplanes doesn't add to the color values, but multiplies them. It originally produced an image with colors in the 0-127 range, and that gets expanded back to 0-248. This would mean you lose some in-between colors, but since it's only RGB565 no channel gets squashed.

Originally Posted by Karlos

Doom RPG?

Yep Used to play the J2ME version a lot back in high school.

[paraj]

Originally Posted by pipper

You could even go one step further and make it so that the screen is reusing the same bitplane for bit 0 and 1.

Maybe that's what you mean, but you want to fill LSB's from MSB's, not other way round right, i.e 0b11110 -> 0b111101 not 0b111100?

Originally Posted by BSzili

Not quite, bumping the bitplanes doesn't add to the color values, but multiplies them. It originally produced an image with colors in the 0-127 range, and that gets expanded back to 0-248. This would mean you lose some in-between colors, but since it's only RGB565 no channel gets squashed.
Yep Used to play the J2ME version a lot back in high school.

Nice, also think this is the only mobile game I ever completed

[waldiamiga]

Originally Posted by paraj

Nice, also think this is the only mobile game I ever completed

Apart from DoomRPG, I also finished the similar Wolfenstein RPG, which was also great to play. Maybe BSzili will make a port of this game as well

[BSzili]

That's not likely as there's no source code for Wolfenstein RPG.