Graphics 8 colors

[+Philsan]

Is it possible to do this?

A foreground color (not standard white) with a black background in Graphics 8 mode (320X192 pixels).

Perhaps using PMG?

[Rybags]

Yes.

 

That image is kinda complex, but it might work better with horizontal reuse of PMGs in 2x mode. You'd probably need to rework the image a bit to get things to fit right.

 

Of course you get the odd PM overlap into normal bg area but if you're dealing with colours BG=$00 and PM=$30 then it'll barely be noticable.

[JayoK]

Yes.

 

That image is kinda complex, but it might work better with horizontal reuse of PMGs in 2x mode. You'd probably need to rework the image a bit to get things to fit right.

 

Of course you get the odd PM overlap into normal bg area but if you're dealing with colours BG=$00 and PM=$30 then it'll barely be noticable.

 

My memory is a little hazy but in Gr.8 can you only select the colour white? I knew you could have only two playfield colours, but I thought they could be any colours from the palette?

[Rybags]

You have 2 lumas of the one colour. PM overlaps override the colour.

 

Due to the way saturation doesn't increase, the colours tend towards white as they get brighter.

[JayoK]

You have 2 lumas of the one colour. PM overlaps override the colour.

 

Due to the way saturation doesn't increase, the colours tend towards white as they get brighter.

 

The PM overlap I understand, but can we not set the background to black and pick red as our only colour?

[PeteD]

You have 2 lumas of the one colour. PM overlaps override the colour.

 

Due to the way saturation doesn't increase, the colours tend towards white as they get brighter.

 

The PM overlap I understand, but can we not set the background to black and pick red as our only colour?

 

You can't pick colours from differnet hue groups. There's black to white then for a red (using the PM overlays) there's dark red to light pinky colours. You'd either end up with a dark red background with a lighter logo or as Rybags said, black bg with PRIOR PMs over it to alter the (what would be grey) logo to a red hue. As he pointed out though you'll get bleeding of the PM hue change into the black background as well.

 

*edit*

It probably wouldn't look too bad with some editing, here's a Gimp mockup of the "bleed" areas.

 

Ignore the odd colour choice The lighter colour is the original shape, darker red is what would show as bleed over the black. That's with 2x expanded pixels for the PMs, not sure there's enough to cover that much area at that size though..

 

Personally I think you may as well just go with a multicolour mode.

 

Pete

Edited February 26, 2010 by PeteD

[Rybags]

The bleed could actually enhance the effect to a degree.

 

Probably go with PF2=00, PF1=04 or 06, and PM overlay colour of 30.

[JayoK]

You have 2 lumas of the one colour. PM overlaps override the colour.

 

Due to the way saturation doesn't increase, the colours tend towards white as they get brighter.

 

The PM overlap I understand, but can we not set the background to black and pick red as our only colour?

 

You can't pick colours from differnet hue groups. There's black to white then for a red (using the PM overlays) there's dark red to light pinky colours. You'd either end up with a dark red background with a lighter logo or as Rybags said, black bg with PRIOR PMs over it to alter the (what would be grey) logo to a red hue. As he pointed out though you'll get bleeding of the PM hue change into the black background as well.

 

 

Pete

 

Ah, got it. Thanks for that, after all this time, I'm still learning.

[PeteD]

There's no way you're going to cover that area with 2x expanded though. It kind of looks ok at that res but you'll only have 160 pixels of coverage, the logo is ~254 (just checked) which means either some clever shuffling around of stuff or moving up to quad PMGs That's gonna look rather poo (like a bad spectrum attribute problem)

 

 

Pete

[PeteD]

 

 

Ah, got it. Thanks for that, after all this time, I'm still learning.

 

It's a real shame it didn't work either by letting you chose bg hue/luma and foreground hue/luma OR bg/fg hue/luma as it does now but the PMG overlays only altering the foreground colour. oh well.

 

 

Pete

[Rybags]

It'd be a lot less painful to do if you split the graphic so each word was on it's own line.

 

First hit on Google-Search:

 

[analmux]

In that case, maybe it's easier to use Antic's narrowscreen mode. Then you can always figure out when the most PM resources are needed, i.e. when using them for generating red OR white palette. Thus, when using PM as red underlays for the text, but when all PMs get outsourced, then switch to inverted gfx: Set playfield to red, and PM to white (at lum 0 = black).

 

This may vary depending on the scanline, changing palette by DLI.

 

F.e., the top word ("THE") is not that wide: then use PM's for the red parts inside the characters, and use a black playfield palette.

 

F.e., the word "HORROR" is very wide: then use PM's for black overlays outside the characters ( = inside inverted graphics), and use a red playfield palette.

 

...However, it's still very tricky.

[emkay]

Inerleaved graphics might be the solution

 

gr.8

gr.15

gr.8

gr.15

 

....

 

and the gr.8 line been overlayed with PM graphics.

 

 

[Irgendwer]

Inerleaved graphics might be the solution

 

gr.8

gr.15

gr.8

gr.15

 

....

 

and the gr.8 line been overlayed with PM graphics.

 

Not a bad idea. You even don't need to do PM overlays for PAL thanks to colour averaging.

http://www.atariage.com/forums/topic/34916-graph2fnt/page__st__725__p__1786016?do=findComment&comment=1786016

[potatohead]

Ataris only have 160 pixel color resolution... Edit @ 40 byte DMA.

 

So, with this overlay bit, what happens exactly? Is it like having control over the color for any two pixels that lie under the P/M graphic?

 

If the background is black, and foreground is some brigher luma, and a player is positioned over the pixels, colored say green, is the product then dark green, and light green in that area of overlap?

 

Too bad artifacting doesn't work on PAL, or that graphic would be really easy. On NTSC machines, just plot every other pixel, carefully positioning the graphic to make the tips align with the active even or odd pixel row required.

 

Otherwise, why not just use one of the 4 color modes, given the color will actually be at that resolution anyway?

 

What I mean is that artifacting reduces effective resolution to 160 pixels, but does do the little sharp tips nicely enough.

 

An overlay only works for a color clock, unless I'm missing something, meaning you get a bright red tip, with some very dark red surrounding it.

 

Either way, without artifacting, there isn't any means to get that sharp tip, unless it's monochrome.

Edited February 28, 2010 by potatohead

[flashjazzcat]

I was very impressed by the PM overlay technique but soon realized that all it does is set the base colour for a single colour clock-wide pixel. So yes - on a black background, you can have a 1 colour pixel wide red PMG and over that set a GR.8 pixel to give the impression that it's a red half-colour clock pixel on a black background. But really, it's just a bright red pixel on a dark red backgound.

[Irgendwer]

I was very impressed by the PM overlay technique but soon realized that all it does is set the base colour for a single colour clock-wide pixel.

...

 

That doesn't matter and is in most cases not really noticeable. It is also used by the JPEG compression

(Chroma Subsampling) to increase compression without disturbing the psycho visual system of humans to much.

[flashjazzcat]

That doesn't matter and is in most cases not really noticeable. It is also used by the JPEG compression

(Chroma Subsampling) to increase compression without disturbing the psycho visual system of humans to much.

I certainly didn't mean to imply it doesn't look good - just that it's an optical illusion. It looks particularly effective on things like BOSS-X, where the surrounding screen areas are white (making dark areas with colour appear black around PM overlays).

[Divya16]

I was very impressed by the PM overlay technique but soon realized that all it does is set the base colour for a single colour clock-wide pixel.

...

 

That doesn't matter and is in most cases not really noticeable. It is also used by the JPEG compression

(Chroma Subsampling) to increase compression without disturbing the psycho visual system of humans to much.

 

Sort of like putting three phosphers next to each other in TVs/Monitors to make it look like a solid color.