How much are you going to zoom into the photo? Unless you're going to blow up the photo to 2 or 3 times video resolution, there's little value in using a high-resolution photo. In fact, Premiere Elements has a max photo size, larger photos than which it will reject outright.
If you're zooming into an area 25% of the photo size in a high-def video, you'll obviously want your photo sized to 7680 pixels horizontal. If you're using a standard 4:3 photo, that means your photo should be 7680x5760 pixels.
That's a lot for the program to deal with so, depending on your computer's power, I'd not recommend working with too many photos this large without rendering. But, if your computer can handle it and the program will accept a photo that size, that's probably the size you should be using.
The 2000x1500 I recommend in this lynda course is more a guideline and and ideal than a rule.
In my first attempts I had neither set "Scale to Frame Size = OFF" nor set the "Hold" times to zero..
Hence I will be redoing these photos (there are about 10 near the beginning of the video) with both these changes.
So it sounds as if its worth reducing the image size beforehand if the photos are to be static but when doing Pan & Zoom (which does make it more interesting) it seems worthwhile to retain full resolution.
You mention a limit within PE concerning photo sizes - do you know what this limit is with PE 13.1?
I was preparing a reply, but I see that you already have one. When finished there, the following is what I have prepared for you to consider because of its relevancy to your question - but did not get a chance to post until now.
1. Please review my comments on Premiere Elements projects, photo size, and photo size as it relates to Pan and Zoom.
It is a long detailed article, you might want to start with the end Commentary and the various points made there.
As to your question on photo size and limit in Premiere Elements, I can address that first hand...
If you have Premiere Elements running as a 32 bit application, then the project will block any still that exceeds a fixed pixel count.
That is detailed my me in the following Adobe thread, post 6
When you are running Premiere Elements as a 64 bit application, you do not get the project keeping you from importing image with pixel count above the limit for the 32 bit application. I do not know the max, but I have taken several files 10000 x 7500 pixels into Premiere Elements 64 bit application without problems. But, just because I could does not mean I should. Level of computer resources will define your personal limit.
HEM, any questions, please do not hesitate to ask.
Since I'm running on a 64-bit WIN7 system I assume I'm running PE also in 64-bit mode:
This is supported by fact that PE appears to be in C:\Program Files\Adobe\ADobe.... & not under C:\programme(x86)\...
Actually I have 2 cameras: one produces 5184 x 3456 which is 17.915.905 & the other 4608 x 3456 which is 15.925.248.
So if I were to be on a 32-bit system the first would fail but the second be OK. As it is it looks as if both work. Famous Last W....
Here I am referring to the appearance or non appearance of a program message about importer error relating to image too large coupled with the impossibility to get beyond that message to sneak the photo into the program.
Premiere Elements Windows 10 through 14/14.1 is a 64 bit application when it is run specifically on Windows 7, 8, 8.1, or 10 64 bit. You will not get any message and blocking import of your jpeg photos into one of those programs at least up to jpeg 10000 x 7500 pixels (that is as high as I have tested)....and I could preview the Timeline with at least 5 of them on that Timeline without issue.
Premiere Elements as a 32 application will give you that too large error if the total pixel count of the jpeg import goes over total pixel count of 16777216 as per the link that I have already posted in your thread.
You should not get the too large message with your present Premiere Elements and computer version. I have actually worked through these details to verify them.
Again, even if you can physically import the 10000 x 7500 jpegs into your project, that does not mean you should. You define your own limits with your computer environment.