Projector / Resolution problems

banja · 19 Sep 2014 at 21:16

I have an Acer P1203 projector which is giving me headaches re higher resolutions.

For a start the manual and specs give slightly confusing info, claiming that it can do 1080p, but elsewhere states that the max resolution is UXGA 1600x1200. That has been my finding as an HDMI fed signal higher than 720p just gives no signal.

Any and all VGA signals gets picked up no problem (although this has been from relatively low resolutions) HDMI from a DVD player is no problem. But HDMI from a mac or blu-ray player gives no pick up at all.

When we've had plenty of resolution options on a macbook we can occasionally get it to play ball, but I'm finding more and more that modern macbooks only offer two (high) resolution options, and it won't pick up the output.

Do any boffins here have an idea?

BunnyKillBot · 20 Sep 2014 at 01:17

I dont know about that projector, but it has been my experience that OSX is absolutely terrible at picking up the correct resolutions a display is capable of. Although confusing at first, you can use a (paid for) tool like SwitchResX to retrieve the raw data and programming in the optimal resolution specifically.

Rroff · 20 Sep 2014 at 01:22

Looks like the native resolution of the projector is 1024x768 so even "HD" content at 1280x720 probably isn't being displayed properly - in theory it should handle a signal upto 1600x1200 but it will be using some kind of scaling on the projector to downsample it to 1024x768 or closest match - you may need to play with the scaling options PC side if you have them to get it to display some resolutions properly.

lucid · 20 Sep 2014 at 01:45

Rroff is on the right lines here.

The projector has a native resolution of 1024x768 pixels. Any claims about it being able to handle any other resolution than 1024x768 would involve interpolation and scaling. So basically, if it's not a 1024x768 source signal, the projector has to either expand or compress it.

The scaler has certain limits. For PC signals it can handle any source signal up to 1600x1200, but it has to squeeze it down so it can be written as a 1024 dots x 768 dots image.

HDTV timings work slightly differently. There's a 16:9 aspect ratio to contend with for a start; so there's unused pixels in the black bars above and below the picture area. The picture area itself has a maximum resolution now of 1024 dots wide x 576 dots high. Second, there's 50Hz signals rather than the PC refresh rate of 60Hz. That means changing the refresh rate of the panel. It's an altogether trickier operation. If the Blu-ray player is set to 1080p/24 then some business projectors just throw in the towel.

There are ways around all these issues (and HDCP) by using very good quality external scaler boxes to resample the image in giive the projector an easier time. However, new, these things cost upwards of £600, and the ones where they have the flexibility to write ant size and shape output resolution are even more money. Used is always an option. It'll still be almost as much as the cost of the projector though.

banja · 20 Sep 2014 at 20:12

Thanks for the help and responses. The manual is confusing and claims it can handle up to 1080p. But elsewhere it states the max resolution from a PC is 1600x1200.