Hi
Just some thoughts,
I assume your compiling a 64bit app?
bgrabitmap 16200x1800 is over half a GB, which is not much, but timage,picture will be the same size, the timage canvas could be the same size, the scrollbox canvas could be similar size, and also the tpanel canvas the scrollbox is in, so if your creating a 32bit exe, you could be hitting the memory limit
If I remember correctly, TImage is a hybrid component, in that it stores the original image bitmap, and displays a seperate copy of it, so a large image in a timage will be bigger than you think? Any image processing like stretch draw, amOn etc, could cause it to choke.