Is there such a thing as a green screen generator?

[Starglider 2]

So we're all familiar with old green monitors that only output green not color.

And we're all familiar with scanline generators that emulate scanlines when using a retro computer with a modern flatscreen.

But is there such thing as a green picture generator that converts a color COMPOSITE picture into green for display on an HDMI TV?

[prowler]

The only old monitor that I am familiar with which outputs green only is an Apricot Hercules monochrome type with a resolution of 720x348 pixels, which I still own, and a Hercules graphics card to go with it.

It's hardly HD, but it produces a very nice, smooth text output for PC DOS applications, which is very easy on the eye.

[Starglider 2]

Ah, yes, well I own a Commodore 1084S-D1 which also has a green/color switch. As does the Phillips CM8833. But my question is more for a little gadget that can connect to a composite cable and turn the color picture green. Then I can plug into my composite to HDMI adapter.

[Sinphaltimus]

I dunno much about this but if you had component video cables I imagine you could just leave off the red and Blue connectors? So maybe a composite to component adaptor/cable?

That's if your TV accepts component.

[Starglider 2]

Originally Posted by Sinphaltimus

I dunno much about this but if you had component video cables I imagine you could just leave off the red and Blue connectors? So maybe a composite to component adaptor/cable?

That's if your TV accepts component.

Great idea! It's for an Apple II. Would that remove some pixels from the picture though, if they are red or blue natively?

Thanks!, Starglider
️ http://youtube.com/perifractic
️ http://patreon.com/perifractic

[Sinphaltimus]

I think all pixels are made of RGD signals and none of them are pure to each one. It maybe hard to see though if the values for red and blue on those pixels were very high. Might almost blend in with the green I'd imagine but I don't know for sure.

[solidcore]

You still require the blue and red channels for green rgb output.

see:
https://upload.wikimedia.org/wikiped...eel_10.svg.png

Also you need to translate red and blue predominant rgb colors to green, eg. A red door becomes a green door with a filter otherwise that door wouldn't show very well in a green only output with red/blue pixels disabled.

Another point to make is that white's show up greenish on the Apple II monitor simply because there is no white. A filter would be required to translate pure white into green hue.

[Sinphaltimus]

So not at all that easy.

[Starglider 2]

Isn't it funny that a black and white or green monitor was old technology and color was hard, but now we have color it's seemingly a big technical challenge to convert it to grayscale, or in this case greenscale.

Are you sure we aren't overthinking it?

Thanks!, Starglider

[solidcore]

Originally Posted by Sinphaltimus

So not at all that easy.

Agreed. However a middle-man between the analog input and digital hdmi output could do it with ease.

A few viable paths come to mind for a green screen HDTV experience from hard to easy:

- Build your own
- Look for products that take rgb analog input and offer a user-configurable filters for the rgb color and that support hdmi output.
- Emulators with Apple II color scheme

Originally Posted by Starglider 2

Isn't it funny that a black and white or green monitor was old technology and color was hard, but now we have color it's seemingly a big technical challenge to convert it to grayscale, or in this case greenscale.

May be plenty of electrical components out there that let you fine-tune the rgb channels to give you the same green output that you need but it certainly wasn't a desire by any means for people to remain in the past and we've all moved on to millions of colors haha.

Have you seen what the apple II looks like without the green crt?

[Starglider 2]

Have you seen what the apple II looks like without the green crt?

Oh yes, full 4 color glory!

Are you sure we aren't over thinking this though?

Thanks!, Starglider
️ http://youtube.com/perifractic
️ http://patreon.com/perifractic

[Rotareneg]

Originally Posted by Starglider 2

Are you sure we aren't over thinking this though?

Thanks!, Starglider
️ http://youtube.com/perifractic
️ http://patreon.com/perifractic

Yes, just get a sheet of transparent green plastic and put it in front of your display, problem solved.

[solidcore]

Originally Posted by Starglider 2

Oh yes, full 4 color glory!

Are you sure we aren't over thinking this though?

Thanks!, Starglider
️ http://youtube.com/perifractic
️ http://patreon.com/perifractic

Can you access the monitor's engineer mode / factory settings and adjust the rgb channels manually haha. Go GREEN!

http://cdn1.goughlui.com/wp-content/...2/IMG_0084.jpg

[Supamax]

Originally Posted by Starglider 2

is there such thing as a green picture generator that converts a color COMPOSITE picture into green for display on an HDMI TV?

Hi ,
I read your question and the posts but I didn't understand why you are wanting such an effect on a modern TV/monitor.. retro-nostalgia?

[Starglider 2]

Originally Posted by Supamax

Hi ,
I read your question and the posts but I didn't understand why you are wanting such an effect on a modern TV/monitor.. retro-nostalgia?

Exactly. I have only ever owned an amber monitor as a child so I only ever experienced the Apple 2E in Amber or green.

Thanks!, Starglider
️ http://youtube.com/perifractic
️ http://patreon.com/perifractic

[Supamax]

Originally Posted by Starglider 2

Exactly. I have only ever owned an amber monitor as a child so I only ever experienced the Apple 2E in Amber or green.

Nice .
After all, we all are still childs in our hearts and want to feel again those '80-'90s magic sensations

[pandy71]

Originally Posted by Starglider 2

But is there such thing as a green picture generator that converts a color COMPOSITE picture into green for display on an HDMI TV?

Just hook Luminance signal (i.e. composite made from RGB) to Green input on your converter... alternatively you can create RGB to Gray (i.e. Luminance aka BW) converter (simple resistor matrix should be sufficient) and hook this to Green input in your HDMI converter.

[Starglider 2]

Originally Posted by pandy71

Just hook Luminance signal (i.e. composite made from RGB) to Green input on your converter... alternatively you can create RGB to Gray (i.e. Luminance aka BW) converter (simple resistor matrix should be sufficient) and hook this to Green input in your HDMI converter.

Aha! So just take the full color output and connect it to the green input and it will look green and contain all the picture data? I thought we were overthinking it.

My switch box is actually an XRGB Mini. The RGB input is essentially SCART. It's going to be used by my Amiga.

Therefore I'll need a cable that goes from the composite out of the Apple IIe, to SCART, wired to Green in the SCART. Or basically with the R & B pins removed from the SCART plug.

Then a SCART splitter cable between Amiga and Apple. All doable! Something like this?:

Apple IIe Composite RCA ---> SCART Green pin only ---> SCART Y-cable ---> XRGB Mini ---> TV

Any reason that wouldn't work? Might the picture be too bright if all the signals are pushed into green?

Thanks!, Starglider
️ http://youtube.com/perifractic
️ http://patreon.com/perifractic

[Stedy]

Hi,

The attached circuit will convert RGB to YPbPr but if you use the Y part, circled in Blue, you'll have a lumuinance signal. I grabbed the circuit from here: http://cds.linear.com/docs/en/applic...ote/an57fa.pdf

If you play about with the 1070R, 549R and 2940R resistors, you can tweak the RGB levels to get the best green level. Feed the output of this to the SCART/RGB to HDMI converter and depending on the converter type, either use the reduced CSync signal (680R in series) if it's SCART input or the composite video signal from the Amiga. Then it should all work.

Ian

[Starglider 2]

Originally Posted by Stedy

Hi,

The attached circuit will convert RGB to YPbPr but if you use the Y part, circled in Blue, you'll have a lumuinance signal. I grabbed the circuit from here: http://cds.linear.com/docs/en/applic...ote/an57fa.pdf

If you play about with the 1070R, 549R and 2940R resistors, you can tweak the RGB levels to get the best green level. Feed the output of this to the SCART/RGB to HDMI converter and depending on the converter type, either use the reduced CSync signal (680R in series) if it's SCART input or the composite video signal from the Amiga. Then it should all work.

Ian

Nice. If you look at my post above yours, wouldn't that work too, without the need for resistors?

What resistors would you recommend I order?