Monitor settings on Pi

So, I’ve got my Pi all working now. It’s not a bad picture on my old VGA monitor – it’s a 1280 × 1024 screen that I share with my Mac. I’ve got a couple of very small niggly issues, though:

- It’s an old monitor, and the colours are pretty washed out: not enough contrast at the higher end, making it hard to tell the difference between, eg, white and the lightest grey in the Wimp palette. There’s no way of fixing this from the monitor’s own controls. On the Mac I use the ColorSync utility to create a modified colour profile to sort this out. I’ve had a look online, but I’m guessing there’s no equivalent for RISC OS?

- By tweaking the config.txt file I’ve got the Pi using the monitor’s native resolution. I’ve selected one of the many built in MDFs from Configure to match this (Acorn AKF95, I think), and it’s almost 100%. The pixels along the vertical axis are exactly lined up. There’s a little blurring horizontally, which is noticeable with the system font. Could this be because the Pi is scaling things for some reason? I haven’t got any overscan set up, and the desktop looks like the right size for the panel, but I’m wondering if there’s some setting I’ve missed to get everything as crisp as possible?

Of course, the best answer would be a proper, new monitor, but the bank account won’t allow it right now :) Any ideas in the meantime?

I run at 1280×1024 and no config.txt modifications were needed. There’s an option in Configure for this resolution when using the Generic MDF, but this may require AnyMode.

Ah – AnyMode looks interesting. I’ll take a look – thanks.

I set my Pi to run the video at 1280×1024, in config.txt – because sometimes the EDID doesn’t get read correctly. I’m guessing the VGA convertor needs to start up and read the values from the monitor in order to have data for the Pi and it might not be ready in time? So I force it.
On the RISC OS side, I patched a 75Hz 1280×1024 mode into RISC OS itself and then set this to be chosen as the default mode (instead of the unreadable full HD).
It is dead easy to make a Pi MDF. Set the resolution to 1280 and 1024. My pixel rate is supposed to be 75Hz (98400) but RISC OS says the display is 57Hz. The monitor says 75Hz because that is what the Pi is outputting. So, I guess “a good looking number” can go in the pixel rate. And everything else? Make it zero. The Pi controls the video timings, not RISC OS.

Chris: you say you are using an Acorn AKF95 which is a CRT, the pixels the computer outputs will never line up properly with red, green and blue phosphor dots on a CRTs mask over more than a small part of the screen, in fact I think getting it close in one axis/part of the screen makes it look worse than having no part aligned!

Rick: you can put 0 as the pixel rate as it is ignored on a PI! Only X and Y are used.

ChrisE: I should have been clearer. My monitor is an LCD flatscreen with a native resolution of 1280×1024. I don’t seem to have a ‘Generic’ option on the drop-down menu from the Screen app in Configure, so I just selected one of the many MDFs that offer that resolution, just to see how far I got. As I say, the vertical resolution is spot-on, but I’m not quite sure why it’s a bit fuzzy on the horizontal.

It’s not a deal-breaker. I’ll have a play with AnyMode to see if that does the trick. I’m also still using OS 5.21 until I’ve got everything safely backed-up and working well – I’ll upgrade to the latest version of the OS once everything’s sorted, in case that makes a difference.

but I’m not quite sure why it’s a bit fuzzy on the horizontal.

That’s the highest frequency part. Old CRTs can be… lacking in the fine details. Try altering config.txt to run the screen slower. Like maybe 60Hz?

Chris: can you check what resolution your monitor is actually receiving?
It is normally given one of the menus.

!Zebra will demonstrate one to one pixel display
The version below I think is 26 bit
http://www.dawnsun.net/riscos/software/zebra

Some one did a 32bit version which we host:
http://www.cjemicros.co.uk/Public/zebra.squ it seems to be a ‘squashed’ file

The app !ScrHelp will tell you what the GPU is sending to the monitor.

Probably not a whole lot of help but I butchered up one of the monitor definition files to make my own too. I was lucky that there was a related model already in there. I really can’t say much for colour correction though. Towards higher resolutions SVGA can end up looking awful. Can, not will. I know cable quality can make a huge difference. As can the pixel clock and refresh rate as said. About all you can do is tinker with it.
I was so glad when I didn’t need to use SVGA any more. Worth noting is SVGA looks like rubbish no matter what on one of my LCD monitors. I think sometimes they just can’t.

Well, after some tweaking I think it’s probably just as Tristan M says – a bit rubbish, but nothing actually wrong. At some point I’ll probably get hold of a new monitor, and in the meantime the Pi display is perfectly usable.

i have somehow managed to screw up my pi’s ability to read EDID (even on a standard config.txt) alway defaults to 640 × 480 :@(