photographer wanted - help with screenshots

[cwilkson]

Not sure where to stick this post. Here goes...

 

After a couple of sleepless weeks, (averaging about an hour a night) I have a *REALLY* cool hardware

prototype to show off. This is something long talked about, but to my knowledge it has never been done.

General consensus was impractical at best, likely impossible. (OOH! A mystery!)

 

I need screenshots, and I have no skill when it comes to photographing TV and monitors. I really need

some high quality images, and I can't get them myself.

 

Any photographers in the SF Bay wanna come over and help me out? It would be much appreciated.

 

-Chris

[cwilkson]

[bump]

 

What? Nobody has a camera and lives in the Bay Area?

 

Come on....15 minutes of your time buys you some pizza and soda

and much gratitude, and helps bring a new 2600 gadget to the market.

 

Somebody help a guy out?

[+Nathan Strum]

Sorry. I could help if you were in the L.A. area.

 

Well, maybe not so much help with the photography, as with the pizza.

 

But the thought's there.

[+Random Terrain]

Am I misunderstanding? You have images on a PC monitor you want to take photos of? If so, why take a photo when you can hit the Print Scr button and edit the screenshot with your favorite photo editing software?

[cwilkson]

Thanks Nathan. Next time you're up north maybe.

[cwilkson]

Thanks, Random. It took me years to figure out the [PRNT SCRN] because my keyboard was broken. But I finally got it. Not really an option this time.

 

Ok, ok. Being all mysterious is seriously defeating me here. It's a VGA board for the 2600. And it works. And it is sweet like honey. So no [PRINT SCREEN] FOR ME.

 

Ok, the cat's out of the bag now. So...anyone want to help me get screen shots of my Atari 2600 Jr. directly driving a Viewsonic E90fb 19" RGB monitor?

There. I said it.

 

Note that this hardware is *not* ready for release. It's prototype hardware, handwired, with the ugliest 50-resistor D2A converters you're likely to see. And it's limited to 21-bit color because I'm using parts I had lying around. And I'm afraid to move it, etc. But it's real and it works and I'm quite willing to preview it for anyone who wants to drop by. I've tested it on the Viewsonic E90fb (19" CRT), a Viewsonic P815 (21" CRT), a Dell P790 (17" CRT), and a Dell 1702FP (17" LCD)

 

So....screen shots? Anyone? This is the best I can do, and they in no way do this thing justice. Not even close. I need your help!!

 

[+batari]

Thanks, Random. It took me years to figure out the [PRNT SCRN] because my keyboard was broken. But I finally got it. Not really an option this time.

 

Ok, ok. Being all mysterious is seriously defeating me here. It's a VGA board for the 2600. And it works. And it is sweet like honey. So no [PRINT SCREEN] FOR ME.

 

Ok, the cat's out of the bag now. So...anyone want to help me get screen shots of my Atari 2600 Jr. directly driving a Viewsonic E90fb 19" RGB monitor?

There. I said it.

 

Note that this hardware is *not* ready for release. It's prototype hardware, handwired, with the ugliest 50-resistor D2A converters you're likely to see. And it's limited to 21-bit color because I'm using parts I had lying around. And I'm afraid to move it, etc. But it's real and it works and I'm quite willing to preview it for anyone who wants to drop by. I've tested it on the Viewsonic E90fb (19" CRT), a Viewsonic P815 (21" CRT), a Dell P790 (17" CRT), and a Dell 1702FP (17" LCD)

 

So....screen shots? Anyone? This is the best I can do, and they in no way do this thing justice. Not even close. I need your help!!

 

That's amazing. So did you need a full frame buffer to pull this off?

[+Nathan Strum]

Ok, ok. Being all mysterious is seriously defeating me here. It's a VGA board for the 2600. And it works. And it is sweet like honey. So no [PRINT SCREEN] FOR ME.

 

Ok, the cat's out of the bag now. So...anyone want to help me get screen shots of my Atari 2600 Jr. directly driving a Viewsonic E90fb 19" RGB monitor?

There. I said it.

 

Note that this hardware is *not* ready for release. It's prototype hardware, handwired, with the ugliest 50-resistor D2A converters you're likely to see. And it's limited to 21-bit color because I'm using parts I had lying around. And I'm afraid to move it, etc. But it's real and it works and I'm quite willing to preview it for anyone who wants to drop by. I've tested it on the Viewsonic E90fb (19" CRT), a Viewsonic P815 (21" CRT), a Dell P790 (17" CRT), and a Dell 1702FP (17" LCD)

 

So....screen shots? Anyone? This is the best I can do, and they in no way do this thing justice. Not even close. I need your help!!

Sweet!!

 

I... want... one.

 

Well... I'd suggest using a digital camera, in a dark room, no flash, on a tripod. A remote shutter (or timer) will keep the camera steadier than trying to press the button. Try to shoot a static image if at all possible, then experiment with the shutter speeds, ISO settings and exposure. You may need some pretty long exposures to get good results. You may also need to use manual focus, if the camera has trouble locking in on the screen. I've had pretty good results doing this shooting off my HDTV. Different games may require different settings, depending on the overall brightness of the image.

 

Otherwise... I could probably figure out a way to do a direct VGA capture where I work. But that's not up there.

[cwilkson]

Heh...yeah, I want one too. Can't wait to finalize the part list so I can spin a real board.

 

Nathan, those are good suggestions. My camera supports...none of them. Well, I can turn off the flash. But that's it. Plus it eats batteries in about 15 minutes. But I've never been able to justify the expense of a new camera. My old roommate had a Canon D20 (I think that was it). He got some nice shots with it for sure. The manual focus and long exposure are what I'm really missing. And a remote shutter/tripod. But I can sorta fake that with a small table and 2 books and some firmly applied pressure. A direct VGA capture sounds nice. But I figure amateur photographers should be easier to find. BTW, I used the flash in a lit room to try to get rid of retrace and moire artifacts. It mostly worked, but it made things really washed out and grainy.

 

Here's SPIDERMAN on my Viewsonic 29GA (29"CRT). Ignore the retrace line...it's a photo artifact. And ignore the keystoning/pincushioning. My 29" needs food badly (a cap kit). And it has convergence issues. But it still looks pretty good if you more than 5 feet away.

Edited April 7, 2009 by cwilkson

[cwilkson]

That's amazing. So did you need a full frame buffer to pull this off?

Missed this last night. Thanks. The victory dance would have been quite embarassing had anyone seen it.

 

Why do a full frame buffer for a scanline based architecture? Just like the Atari, The CyberTech VGA Card draws (almost) on the fly. I'm buffering a single scan line. Actually, a frame buffer might have been easier, but I did this with low parts count in mind.

[+batari]

That's amazing. So did you need a full frame buffer to pull this off?

Missed this last night. Thanks. The victory dance would have been quite embarassing had anyone seen it.

 

Why do a full frame buffer for a scanline based architecture? Just like the Atari, The CyberTech VGA Card draws (almost) on the fly. I'm buffering a single scan line. Actually, a frame buffer might have been easier, but I did this with low parts count in mind.

I though you might have done it that way but is it just a single scanline or two you are buffering? it seems a single scanline would require a dual port RAM?

[cwilkson]

That's amazing. So did you need a full frame buffer to pull this off?

Missed this last night. Thanks. The victory dance would have been quite embarassing had anyone seen it.

 

Why do a full frame buffer for a scanline based architecture? Just like the Atari, The CyberTech VGA Card draws (almost) on the fly. I'm buffering a single scan line. Actually, a frame buffer might have been easier, but I did this with low parts count in mind.

I though you might have done it that way but is it just a single scanline or two you are buffering? it seems a single scanline would require a dual port RAM?

Let me think about that. I'm definitely using a dual port. I guess it's more acurate to say that it's a 2 line buffer. Here's the easiest way to describe it. At any given time, one line is being written to the buffer, while the previous line is being read from the buffer.

[Emehr]

That's very sweet! How much cutting or soldering into the Atari did you have to do?

[cwilkson]

That's very sweet! How much cutting or soldering into the Atari did you have to do?

As with all of the CyberTech products, the TIA is moved from the motherboard to a daughter board. The daughter board plugs into the TIA socket on the motherboard. I may do this one differently for the general release, but that's how the prototype is done.

[yuppicide]

Sounds awesome.

 

You know.. if you ever do justify a new camera, realize that today's cameras will last a lot longer off a set of batteries. My old camera latest about 15-20 mins too. New ones can last hours on Alkaline or days off rechargable.

 

For $30 Energizer sells a charger that will recharge AA's in 15 mins!

[Fangorn81]

Got any pics of the actual board setup? I know you said it looks a mess, just curious though.

[cwilkson]

Got any pics of the actual board setup? I know you said it looks a mess, just curious though.

Nope. It's really too much of a mess and a bit embarassing. That's why those first two photos were cropped. I'll definitely post more photos in the coming weeks though. I might have to look into that AA recharger. I use a 6V power pack for most photos, but that tethers me to an outlet...adding limitations to an already quite limited camera. Every time I have a new photo-worthy project in the pipe, I re-evaluate my camera budget. Still below the ZBB line though.

[Longhorn Engineer]

Sweet! Defiantly interested. If you can set the shutter time a wee bit longer should help out. When I take pictures of my screens I just set it to auto and take a whole bunch till the camera finally takes one that looks good. I have a crappy point and shoot digital tho.

 

Wait if this is VGA then Component is only a few steps away!

Edited April 9, 2009 by Longhorn Engineer

[yuppicide]

I use a Snaps on A Bottle sometimes. It's $8 bucks from Compact Impact:

 

http://tinyurl.com/cjxrql

 

It's a small adapter that turns a water bottle into a tripod. This way I never get any blurry shots due to hand movement.

 

The camera I have also has a 3 or 10 second timer mode, so I can set it to go off in 3 or 10 seconds and not even be touching the camera. Thus further reducing any type of hand shaking.

[cwilkson]

Sweet! Defiantly interested. If you can set the shutter time a wee bit longer should help out. When I take pictures of my screens I just set it to auto and take a whole bunch till the camera finally takes one that looks good. I have a crappy point and shoot digital tho.

 

Wait if this is VGA then Component is only a few steps away!

Mine is a crappy point and shoot too. HP 620. I think I got it in 2000, maybe 2001, for CGE. Easy to use, decent stills, decent movies, poor white balance, poor battery life, no manual adjust. And it's big. And the shutter lag. Oh god the shutter lag. I almost threw the thing away at Johnson Space Center after missing a candid shot. I tried to launch it off the tram, but my mom caught my wrist just as I started my forward motion.

 

I hadn't thought about it. But once I successfully recover the YUV the colorspace conversion is just some math in QBasic. So yeah, I think component is maybe possible. (is that YCrCb? I don't know...I haven't studied component.)

 

I use a Snaps on A Bottle sometimes. It's $8 bucks from Compact Impact:

 

http://tinyurl.com/cjxrql

 

It's a small adapter that turns a water bottle into a tripod. This way I never get any blurry shots due to hand movement.

 

The camera I have also has a 3 or 10 second timer mode, so I can set it to go off in 3 or 10 seconds and not even be touching the camera. Thus further reducing any type of hand shaking.

 

That's kinda cool. Especially if you have a small camera. Mine would probably tip over even a full bottle. Unless it's a 2-liter. I do think it has a timer, maybe 10 seconds. But with the other short comings I haven't tried to use that feature.

[+Nathan Strum]

(is that YCrCb? I don't know...I haven't studied component.)

YP_bP_r

 

That's kinda cool. Especially if you have a small camera. Mine would probably tip over even a full bottle. Unless it's a 2-liter.

Use a 1/4" bolt sticking through a piece of plywood. All camera mounts use 1/4" threads.

[cwilkson]

That's kinda cool. Especially if you have a small camera. Mine would probably tip over even a full bottle. Unless it's a 2-liter.

Use a 1/4" bolt sticking through a piece of plywood. All camera mounts use 1/4" threads.

Yeah, if I had that remote shutter I'd be all over this. But waiting 10 seconds for each shot, hoping one will turn out is too painful. I'm about to talk myself into a new camera. So I'll quit on this topic.

(is that YCrCb? I don't know...I haven't studied component.)

YP_bP_r

Thanks. My head hurts now. A lot. But it confirms my suspicions...it's all Evil Math. After my head quits hurting I'll try to understand what I just read. (rinse...repeat...) Since you're listening Nathan, does this sound right for generating my RGB values? Note: I'm being lazy about using ['] characters because I'm not sure where to put them in this application. Because I'm not really sure what I'm starting with.

 

The TIA generates Y/C internally. I started with the (quite false) assumption that the signals generated are perfect. And I assumed 8-bit resolution (0-255) for all my end variables. That yields the following starting point:

• 1) Color 1 has a phase angle of 180 degrees.
  2) Colors are spaced in equal phase steps of -24 degrees. (Color 2 = 156 degrees, etc.)
  3) All 15 colors have the same saturation as 75% pure blue. (R=0,G=0,B=255*.75) Having the same saturation is required to be "perfect" but the actual level is arbitrary. I chose this because it's a known point for which I can solve all the equations. It's somewhere between the saturation levels used by consoles with the pin 6 resistor (more saturated) and those without (less saturated).
  4) Luma has 7 equally spaced steps.
  

These are my colorspace conversion equations:

• [Eq. 1] Y = 0.151 * R + 0.297 * G + .058 * B
  [Eq. 2] R = 1.975 * Y + 2.251 * V
  [Eq. 3] G = 1.975 * Y - 0.779 * U - 1.146 * V
  [Eq. 4] B = 1.975 * Y + 4.013 * U
  [Eq. 5] C = S * sin(color_angle + wt)
  [Eq. 6] U = C * 2sin(wt)
  [Eq. 7] V = C * 2cos(wt)
  [Eq. 8] Unorm = cos(color_angle)
  [Eq. 9] Vnorm = sin(color_angle)
  [Eq. 10] U = S * Unorm
  [Eq. 11] V = S * Vnorm
  

If this were a receiver circuit, I could use Eqs. 5-7 and some convoluted trigonometry and algebra to get U and V, but since I'm trying to make a lookup table and I already know the color angle of pure blue (= 347) and all of the TIA color angles I can directly compute U and V, normalized to -1 <= Unorm,Vnorm <= 1, from Eqs. 8-9. For 75% pure blue, I know the RGB triplet (= 0,0,191). From Eq. 1, I get Y = 11. Then from Eq. 4, I get U = 42. From Eq. 10, S = U/Unorm = 43.25. I can get U and V for all the colors using this value for S and Eqs. 10-11.

 

For black, R=G=B=0. For white, R=G=B=255. From Eq. 1, I get 0 <= Y <= 129. That gives Y = LUM[2:0] * 129/7.

 

Now I've computed the complete YUV color space for the TIA. From here I just have to convert YUV to RGB using Eqs. 2-4. Or convert YUV to YPrBr using equations (TBD).

 

BTW, I'm attaching a palette file for the Stella emulator(the .zip file), and a color test rom for those who are interested in seeing what this looks like. Here's an HTML color chart too.

 

CYBERTEC.zip

colors.bin

COLORS.HTM