If you're sure you want to use After Effects, you could try the following expression into the opacity field:
Each image will need to be it's own layer. For each image layer, alt + click the stopwatch for the opacity to open the expressions editor, then paste in this code:
visible = 2; // how long the layer is visible for in seconds
transition = 0.05; // how long it takes for the layer to appear and disappear
appear = (index-1) * visible;
disappear = index * visible;
fxin = linear(time, appear, (appear+transition), 0,100);
fxout = linear(time, disappear-transition, disappear, 0, -100);
opacity = fxin +fxout;
opacity
This will make the photos appear in the order the layers are in. If you are looking for a random order, I found a script that lets you randomize layer order:
{
var myComp = app.project.activeItem;
var n = myComp.numLayers;
var myLayers = [];
var myIdx = [];
for (var i = 1; i<= n; i++){ myIdx[i-1] = i; myLayers[i-1] = myComp.layer(i); } var idx; var temp; for (var i = 0; i < myIdx.length; i++){ idx = i + Math.floor(Math.random()*(myIdx.length - i)); temp = myIdx[i]; myIdx[i] = myIdx[idx]; myIdx[idx] = temp; } for (var i = 0; i < myIdx.length; i++){ myLayers[myIdx[i]-1].moveToBeginning(); } }
Sourced from: https://creativecow.net/forums/thread/randomize-layer-order/
Hope that helps.