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AuthorTopic: Scandoubler output looks horrible on TFT, but great on CRT  (Read 2536 times)

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Offline motorollin

Scandoubler output looks horrible on TFT, but great on CRT
« on: April 26, 2007, 09:35:18 PM »
I've got my DCE internal scandoubler installed in my A4000. On my LCD TV, the scansoubler output looks awful. A large amount of the picture is off the screen. The quality is very poor, and there horizontal bars scrolling down the screen.

I brought a 17" CRT home from work today and tried the scandoubler output on that. It looked perfect - absolutely brilliant quality. I'm just wondering if this is normal? Why would the quality be so bad on the TFT? Is it just because the resolution from the scandoubler is not the optimal resolution of the screen?

This is not really a problem as I can just keep the CRT. I'm just curious about why it would happen.

--
moto
Code: [Select]
10  IT\'S THE FINAL COUNTDOWN
20  FOR C = 1 TO 2
30     DA-NA-NAAAA-NAAAA DA-NA-NA-NA-NAAAA
40     DA-NA-NAAAA-NAAAA DA-NA-NA-NA-NA-NA-NAAAAA
50  NEXT C
60  NA-NA-NAAAA
70  NA-NA NA-NA-NA-NA-NAAAA NAAA-NAAAAAAAAAAA
80  GOTO 10
 

Offline adolescent

Re: Scandoubler output looks horrible on TFT, but great on CRT
« Reply #1 on: April 26, 2007, 09:40:07 PM »
What screenmode?  Some TFT screens have trouble with PAL modes (31kHz/50Hz).  Mine looks okay in PAL High Res but gives an "signal out of range" error, but works fine in NTSC.
Time to move on.  Bye Amiga.org.  :(
 

Offline motorollin

Re: Scandoubler output looks horrible on TFT, but great on CRT
« Reply #2 on: April 26, 2007, 09:58:49 PM »
It was PAL. I didn't think of trying NTSC since the screen is PAL.

--
moto
Code: [Select]
10  IT\'S THE FINAL COUNTDOWN
20  FOR C = 1 TO 2
30     DA-NA-NAAAA-NAAAA DA-NA-NA-NA-NAAAA
40     DA-NA-NAAAA-NAAAA DA-NA-NA-NA-NA-NA-NAAAAA
50  NEXT C
60  NA-NA-NAAAA
70  NA-NA NA-NA-NA-NA-NAAAA NAAA-NAAAAAAAAAAA
80  GOTO 10
 

Offline cv643d

Re: Scandoubler output looks horrible on TFT, but great on CRT
« Reply #3 on: April 26, 2007, 10:02:49 PM »
Same here on my DCE scandoubler. It is a problem with TFT's.

I am running my scandoubler to a 23 inch TFT and I had to auto adjust the image before it became good. And by good it is still not perfect, but the image is at least centered.

On a CRT the picture is crystal clear, not much you can do about it.

(Had the same problem with an Amiga 3000 on an old 15 inch TFT, the funny thing is my A1200 with DCE scandoubler wont output any image on the same 15 inch TFT).
Amiga articles
"New shell. It was finished a while back, but I still see bugs, haha" - SSolie
 

Offline motorollin

Re: Scandoubler output looks horrible on TFT, but great on CRT
« Reply #4 on: April 26, 2007, 10:11:29 PM »
Oh well, I'll keep the CRT. Looks like I'll have an LCD TV for sale soon :-)

--
moto
Code: [Select]
10  IT\'S THE FINAL COUNTDOWN
20  FOR C = 1 TO 2
30     DA-NA-NAAAA-NAAAA DA-NA-NA-NA-NAAAA
40     DA-NA-NAAAA-NAAAA DA-NA-NA-NA-NA-NA-NAAAAA
50  NEXT C
60  NA-NA-NAAAA
70  NA-NA NA-NA-NA-NA-NAAAA NAAA-NAAAAAAAAAAA
80  GOTO 10
 

Offline LoadWB

Re: Scandoubler output looks horrible on TFT, but great on CRT
« Reply #5 on: April 26, 2007, 10:13:02 PM »
I've run into the same myself.  The SD/FF looks great on all CRTs, but only looks good on a 19" Dell FP1901.  It looks crappy on the 20" FP2001, and distorted on a 17" LCD.

I believe this is related to the "optimal resolution" of the LCD.
 

Offline mbrantley

Re: Scandoubler output looks horrible on TFT, but great on CRT
« Reply #6 on: April 27, 2007, 03:48:33 PM »
Yeah, I ran into the same problem when hooking up an Amiga 3000 to a Samsung 19 inch LCD monitor that became "surplus" when I put a 22-inch LCD on my Mac yesterday. When you give the LCD a resolution that is not "optimum," the monitor must scale the image to its native resolution. The scaling, obviously, is imperfect. I think for my 3000 I will be going back to the 14-inch CRT that I bought at a thrift store for $15 and figure out something else to do with my nice (but not for Amiga) 19-inch LCD.
 

Offline lionstorm

Re: Scandoubler output looks horrible on TFT, but great on CRT
« Reply #7 on: April 28, 2007, 10:22:44 AM »
what about using a smaller size LCD TV like 640x480 pixels instead of all the other beast (800x600, 1024x768, 1280x1024).

picture quality might be better  :idea:
 

Offline bloodline

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Re: Scandoubler output looks horrible on TFT, but great on CRT
« Reply #8 on: April 28, 2007, 11:55:47 AM »
Sounds like the frequency output of the Scandoubler is very slightly too low for the LCD display...

Offline alexh

Re: Scandoubler output looks horrible on TFT, but great on CRT
« Reply #9 on: April 28, 2007, 12:04:16 PM »
Quote

motorollin wrote:
I've got my DCE internal scandoubler installed in my A4000.

Dont those suck for AGA screen modes? They are only 16-bit.
 

Offline A4000_Mad

Re: Scandoubler output looks horrible on TFT, but great on CRT
« Reply #10 on: April 29, 2007, 07:47:53 PM »
@ moto

Congrats on getting your scandoubler mate  :pint:

Are you seeing the boot picture that I set it up with for you now? :-D


A4000 Mad

A4000 Mad
 

Offline Karlos

Re: Scandoubler output looks horrible on TFT, but great on CRT
« Reply #11 on: April 29, 2007, 08:10:22 PM »
Quote

alexh wrote:
Quote

motorollin wrote:
I've got my DCE internal scandoubler installed in my A4000.

Dont those suck for AGA screen modes? They are only 16-bit.


I can't remember if it was this particular model but I remember some of them had a bizzare RGB 8:4:4 resolution which, understandably looks awful if you aren't already restricted to OCS/ECS 12-bit colour depth.

I can't quite understand why anybody would pick RGB 8:4:4 when RGB 5:6:5 (regular 16-bit) makes much more sense. Even if you were forced to split the 16 bits into one 8-bit channel and 2 4-bit ones, at least make the green one 8-bit, since it contributes the most to the overall luminance.
int p; // A
 

Offline motorollin

Re: Scandoubler output looks horrible on TFT, but great on CRT
« Reply #12 on: April 29, 2007, 08:42:33 PM »
Well it looks as good through the DCE Scandoubler as it does directly from the RGB port, so I'm happy.

--
moto
Code: [Select]
10  IT\'S THE FINAL COUNTDOWN
20  FOR C = 1 TO 2
30     DA-NA-NAAAA-NAAAA DA-NA-NA-NA-NAAAA
40     DA-NA-NAAAA-NAAAA DA-NA-NA-NA-NA-NA-NAAAAA
50  NEXT C
60  NA-NA-NAAAA
70  NA-NA NA-NA-NA-NA-NAAAA NAAA-NAAAAAAAAAAA
80  GOTO 10
 

Offline Damion

Re: Scandoubler output looks horrible on TFT, but great on CRT
« Reply #13 on: April 30, 2007, 02:48:49 AM »
Yeah, on the right monitor mine looked good also. AGA games/demos, even HAM modes with Shapeshifter seemed to look as they should.

 

Offline derringer3

Re: Scandoubler output looks horrible on TFT, but great on CRT
« Reply #14 on: April 30, 2007, 07:01:30 AM »
Dudes if you try the old games in lcd you will be always got a very pixelized graphics. Because nowadays most lcd's got the optimal resolution somewhere 1024*768 or better. And crt-s handled the pixel array a little bit different than lcd-s. So go for a bigger workbench at your home to put on a good crt.  :-D
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