digital pic quality when projected in auditorium??

Hi out there... I hope I've selected the right forum for this ... This may actually fit somewhere else ... or in several places ... (??? tell me where to post??)

I am producing a digital slideshow to be shown in an auditorium (actually an "all-purpose" room ... basketball etc. ... that fits at least 600 people). Most of the photos contributed were digital and look okay "to me" (on my monitor). However, I'm worried about how the following types of photos will look when projected --

-- Submissions that appear to have been taken with a lower resolution (?? don't know how low ... or maybe that's not the problem ... but I know they were taken digitally and, while they don't look TERRIBLE, they don't look as good as some of the other digital submissions)

-- Photos that I cropped to focus on a particular portion of the photo... I'm not sure how the projected image will be affected by enlarging (via the handles) a cropped image

Basically, if it looks good on my monitor screen, how confident can I be that it'll look okay up on the "movie screen"? Will the lower resolution pics that look "okay" on my monitor look that much worse when projected as a larger image?

I have played with sharpen, levels etc. (Picture It!) ... though I can't claim expert understanding of them! And, I know there is only so much I can do with those lower resolution pics ... but any advice will be greatly appreciated!! Are there any tell-tale signs I should look for ... litmus tests?? Or general guidelines? Or do I just go with my gut feeling about how the pic looks?

Also, the projector will be displaying the images from a DVD rather than the monitor ... I'm thinking that probably means I need to keep the image within the "TV" screen size (luckily, I do have "guidelines" in my software) ... Does anybody know for sure?

This slideshow is (gasp!) Wednesday night (yes, pretty much produced, but I want to go back and make sure these few photos are the best I can make them) ... However, thoughts & advice provided AFTER Wednesday are still welcome/desired/sought-after ... since this will not be the last time I do produce something like this....

Thanks in advance!
Mary

I'm not going to be a whole lot of help because I've never personally used a digital projector. I've seen some presentations that had excellent image quality, and the resolution of most projectors is roughly that of a monitor (800x600 or 1024x768). Even at the higher of those two, it works out to less than one megapixel.

If you crop an image, the quality of the final image will depend on a lot of things: how sharp is it, how much are you cropping and what was the resolution? When you crop, the part of the image that you keep is magnified more than it was. This will make any sharpness problems worse (same as making a big print from a negative) or any other problems with it more apparent. If you only crop a little, then the resolution of the original probably won't matter much. If you crop a lot, you still want to have at least as many pixels left as the resolution of the monitor (again, 800x600 or 1024x768). Of the three points that I listed, I'd say sharpness in the original image is the most important (for example, I've seen great 20x30 prints from 4mp cameras, which is pretty low resolution for a print).

I'd go with the gut feeling - it's the projected image that counts, not the numbers!

any way you can try the pictures on the equipment you will be using a day or two before, it will give you a chance to work out any problems. I haven't got any experience with projectors but I do have many years of experience giving programs before large groups. If I could only give you one suggestion it would be to run through what you are going to do ahead of time and work out any problems you may encounter. Finding out that things don't work in the presentation is definitely not the way to go. Run through everything ahead of time. It's like watching a magician do a trick that doesn't work it doesn't empress anyone. Be sure you know what is going to happen ahead of time. Don't get caught off guard. :) :)

If you could do a run through with the equipment in the location the presentation will be at during the same time of day would be best.

I put together all the scripts for each of the leaders for my son's Eagle Court of Honor in Boy Scouts. I planned everything to the last detail. All props were checked out and the candles used during the ceremony were all timed so I knew they would not burn out. Everything was gone over so that there would be NO mistakes and the ceremony would be perfect. The only problem was that I didn't run through it in the church where it was going to take place. Everything worked as planned until the air conditioner turned on during the presentation and and blew directly on the candles causing them to burn several times faster than normal and caught the holders on fire. The point of the story is that if you don't check this out ahead of time in the same location you might find something you didn't plan on either such as a light problem that may mess up the projected image. It makes a big difference when you know everything will work right ahead of time. Good luck!! :D