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I believe this was explained somewhere, but I cannot dig it up.
I attach some test patterns (taken from an emulator), and how the screen renders them. Horizontally there seem to be a "virtual pixel" which is spread half on the top and half on the bottom of the "virtual pixel" position, which corresponds to the separation line of two physical pixels.

ggscreen.zip (3.58 MB)

Not a techie here, but I have noticed that pattern while programming on my Game Gear too.
Especially the white square on a black background, sometimes had "gray" borders on the top and bottom of the square.

I wonder if this is some fault when calibrating the screens at the factory, and the image would be squished horizontally for a few pixels ?
Is there a known potentiometer somewhere that could compensate for this (like old CRT computer screens allowed to) ?

kamillebidan wrote

I believe this was explained somewhere, but I cannot dig it up.

There was something here.

Tom wrote

kamillebidan wrote

I believe this was explained somewhere, but I cannot dig it up.
There was something here.

Thank you, yes I was referring exactly to this thread

I also posted some info about this in the below thread.

https://www.smspower.org/forums/18660-GameGearLCDBlurAndPossibleVariations

My conclusion after lots of testing and looking into the behavior extensively is that it was a deliberate design choice by Sega.

It affects all models from the VA0 to VA5, and considering VA4/VA5 use slightly redesigned LCD panels I have to assume it was intentional, perhaps as a mechanism to simulate some of the blending/persistence of vision from CRT displays that are used by SMS games like Sonic (eg, standing behind a waterfall).

thatawesomeguy wrote

perhaps as a mechanism to simulate some of the blending/persistence of vision from CRT displays that are used by SMS games like Sonic (eg, standing behind a waterfall).

Thank you for the link to your thread, I missed it. My findings match yours, and indeed your explanation seems the only one for which it makes sense to intentionally blur the image.

thatawesomeguy wrote

I also posted some info about this in the below thread.

-link-

My conclusion after lots of testing and looking into the behavior extensively is that it was a deliberate design choice by Sega.

Thank you for this topic. I had noticed the pixel blur when displaying graphics on my homebrew and the thought that I could have had a defective unit was bothering me.

But I can live with the fact that Sega didn't want their screen to look too good to help the games look... better!

I wouldn't say they didn't want their games to look too good, they did what they could with the LCD tech of the time.

What I am saying though is that if you've ever played a GG or SMS game in an emulator you may notice that while the pixels are very sharp and clear, some effects that games relied on to get faked transparency or extra colours through blending of neighboring pixels won't look right.

I don't have any definitive evidence that the blur was intended to help reproduce some of the traits of a phosphor display, but it seems most likely based on the persistence of this behavior across all the hardware revisions in addition to noticing during my reverse engineering efforts with the LCD hardware, the behavior originates with the on glass driver IC and not in the LCD matrix making it less likely to be a manufacturing defect. It could have been a bug in the driver IC, but again the VA4/VA5 use an entirely new driver IC with a different pin package and I can't fathom them not noticing such a bug during the design of the new IC, by process of elimination it, therefore, has to have been deliberate by design.

thatawesomeguy wrote

I wouldn't say they didn't want their games to look too good, they did what they could with the LCD tech of the time.
[...]

Oh and I agree with that, I didn't say that they didn't want the games to look good!

On the contrary, I agree with your theory that they calibrated the screen that way to allow blending pixels to allow for extra effects.

Personally I really liked how it was taken advantage of in Sonic 1, particularly in the shallow water sections of Jungle Zone. On an emulator, there is a checkerboard pattern underwater, but on real hardware (both on my Majesco Game Gear and the earlier revision I used to play on) it shows as really nice wavy effect, I think. :)

Quote

It could have been a bug in the driver IC, but again the VA4/VA5 use an entirely new driver IC with a different pin package and I can't fathom them not noticing such a bug during the design of the new IC, by process of elimination it, therefore, has to have been deliberate by design.

To be fair to Sega, I think that if they had changed how it looked between revisions, they would have ended up in a similar situation as the PSP's different models.

A lot of PSP games used dithering, and the PSP's original screen hid this relatively well. However, Sony released newer revisions of the console with sharper screens, which made the dithering more obvious. I remember people on forums complained that the "better" screens made games look worse...

Personally, I didn't care about that issue: I was mostly emulating old games on my PSP anyway! :D

Author	Message
kamillebidan Joined: 25 Feb 2013 Posts: 384 Location: Osaka	An analysis of the gg screen Posted: Mon Mar 14, 2022 11:41 am
	I believe this was explained somewhere, but I cannot dig it up. I attach some test patterns (taken from an emulator), and how the screen renders them. Horizontally there seem to be a "virtual pixel" which is spread half on the top and half on the bottom of the "virtual pixel" position, which corresponds to the separation line of two physical pixels. ggscreen.zip (3.58 MB)

armixer24 Joined: 12 Aug 2021 Posts: 73	Posted: Mon Mar 14, 2022 12:56 pm
armixer24 Joined: 12 Aug 2021 Posts: 73	Not a techie here, but I have noticed that pattern while programming on my Game Gear too. Especially the white square on a black background, sometimes had "gray" borders on the top and bottom of the square. I wonder if this is some fault when calibrating the screens at the factory, and the image would be squished horizontally for a few pixels ? Is there a known potentiometer somewhere that could compensate for this (like old CRT computer screens allowed to) ?

Tom Joined: 16 May 2002 Posts: 1356 Location: italy	Posted: Mon Mar 14, 2022 1:11 pm
Tom Joined: 16 May 2002 Posts: 1356 Location: italy	kamillebidan wrote I believe this was explained somewhere, but I cannot dig it up. There was something here.

kamillebidan Joined: 25 Feb 2013 Posts: 384 Location: Osaka	Posted: Tue Mar 15, 2022 7:34 am
	Tom wrote kamillebidan wrote I believe this was explained somewhere, but I cannot dig it up. There was something here. Thank you, yes I was referring exactly to this thread

thatawesomeguy Joined: 25 Jul 2007 Posts: 730 Location: Melbourne, Australia	Posted: Sun Mar 20, 2022 10:57 am
	I also posted some info about this in the below thread. https://www.smspower.org/forums/18660-GameGearLCDBlurAndPossibleVariations My conclusion after lots of testing and looking into the behavior extensively is that it was a deliberate design choice by Sega. It affects all models from the VA0 to VA5, and considering VA4/VA5 use slightly redesigned LCD panels I have to assume it was intentional, perhaps as a mechanism to simulate some of the blending/persistence of vision from CRT displays that are used by SMS games like Sonic (eg, standing behind a waterfall).

kamillebidan Joined: 25 Feb 2013 Posts: 384 Location: Osaka	Posted: Mon Mar 21, 2022 11:51 am
	thatawesomeguy wrote perhaps as a mechanism to simulate some of the blending/persistence of vision from CRT displays that are used by SMS games like Sonic (eg, standing behind a waterfall). Thank you for the link to your thread, I missed it. My findings match yours, and indeed your explanation seems the only one for which it makes sense to intentionally blur the image.

armixer24 Joined: 12 Aug 2021 Posts: 73	Posted: Tue Mar 22, 2022 6:51 pm
armixer24 Joined: 12 Aug 2021 Posts: 73	thatawesomeguy wrote I also posted some info about this in the below thread. -link- My conclusion after lots of testing and looking into the behavior extensively is that it was a deliberate design choice by Sega. Thank you for this topic. I had noticed the pixel blur when displaying graphics on my homebrew and the thought that I could have had a defective unit was bothering me. But I can live with the fact that Sega didn't want their screen to look too good to help the games look... better!

thatawesomeguy Joined: 25 Jul 2007 Posts: 730 Location: Melbourne, Australia	Posted: Wed Mar 23, 2022 7:43 am
	I wouldn't say they didn't want their games to look too good, they did what they could with the LCD tech of the time. What I am saying though is that if you've ever played a GG or SMS game in an emulator you may notice that while the pixels are very sharp and clear, some effects that games relied on to get faked transparency or extra colours through blending of neighboring pixels won't look right. I don't have any definitive evidence that the blur was intended to help reproduce some of the traits of a phosphor display, but it seems most likely based on the persistence of this behavior across all the hardware revisions in addition to noticing during my reverse engineering efforts with the LCD hardware, the behavior originates with the on glass driver IC and not in the LCD matrix making it less likely to be a manufacturing defect. It could have been a bug in the driver IC, but again the VA4/VA5 use an entirely new driver IC with a different pin package and I can't fathom them not noticing such a bug during the design of the new IC, by process of elimination it, therefore, has to have been deliberate by design.

armixer24 Joined: 12 Aug 2021 Posts: 73	Posted: Wed Mar 23, 2022 6:53 pm
armixer24 Joined: 12 Aug 2021 Posts: 73	thatawesomeguy wrote I wouldn't say they didn't want their games to look too good, they did what they could with the LCD tech of the time. [...] Oh and I agree with that, I didn't say that they didn't want the games to look good! On the contrary, I agree with your theory that they calibrated the screen that way to allow blending pixels to allow for extra effects. Personally I really liked how it was taken advantage of in Sonic 1, particularly in the shallow water sections of Jungle Zone. On an emulator, there is a checkerboard pattern underwater, but on real hardware (both on my Majesco Game Gear and the earlier revision I used to play on) it shows as really nice wavy effect, I think. :) Quote It could have been a bug in the driver IC, but again the VA4/VA5 use an entirely new driver IC with a different pin package and I can't fathom them not noticing such a bug during the design of the new IC, by process of elimination it, therefore, has to have been deliberate by design. To be fair to Sega, I think that if they had changed how it looked between revisions, they would have ended up in a similar situation as the PSP's different models. A lot of PSP games used dithering, and the PSP's original screen hid this relatively well. However, Sony released newer revisions of the console with sharper screens, which made the dithering more obvious. I remember people on forums complained that the "better" screens made games look worse... Personally, I didn't care about that issue: I was mostly emulating old games on my PSP anyway! :D

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