Beginner Questions about projecting images with Keynote

I give a series of talks to local groups about wildlife topics. I like to keep people awake by regularly breaking into simple moving images and occasional graphic effects etc. I like the images to be displayed at a high quality: it takes a long time to take and process a good wildlife image so I think it's worth it. Currently I use either a Macbook or, rarely an iPad as the source. I use Keynote, just dragging and dropping images onto the slides. Having used PowerPoint professionally for years I cannot believe how much better I find Keynote in both the production and quality of displayed experience.

However! I'm not very technical, in using Keynote are the images reduced in quality compared to showing them from an Aperture or Lightroom slideshow? If so, by how much and what should I look out for?

I use a cheap Acer projector, the images are not as sharp as my 27 inch Mac. Areas of almost single colour (OOF backgrounds etc) appear posterised in some images when projected, no hint on desktop screen. Are these problems anything to do with the display programs or just a result of a cheap and probably nasty projector?

If I need to upgrade the projector what should I be looking for?

Sorry if these are really basic questions!

I can't look now as I don't have my Mac. But if I recall correctly you have to specify the output format and resolution for keynote. If you match it to that of the projector it will look fantastic. That is the only area where PowerPoint has the upper hand as it does it automatically.

That's really helpful dejongj. I'll investigate. I take it that you don't think Keynote reduces the quality compared to a straight projection of an image? I'm hoping that's the case because of Keynotes other facilities.

Not in my experience. I normally match it to my 1440x900 projector and the quality looks fantastic. Both still and moving images. I love it