Memory error when creating image styles
What's the size of your image? For scale you may need roughly:

X * Y * 4 (bytes per pixel) * 2 (for source and destination image) * 2 ( to make sure there is enough RAM for computation).

Now, core can require up to 32 MB, and modules can easily double or even quadruple this. So, let's optimistically assume your core + modules only use 64MB. That leaves other 64MB. It means you can safely scale images up to 4194304px. It seems you have enough memory for 4Mpx input images. Anything larger can cause this error and it will not be anything surprising.