what is your final output? is it for screen? is it for print?

cause in the case that it is just for screen usage and you are not going to zoom in. There is absolutely no need to load an image with such a high resolution.  In other cases you can load it that large, and then use the width and height variables when defining the image size.

like this : image(img,0,0,width,height)

this way it gets scaled down to fit the screen.

it still might be better to work with a low res version in your sketch and replace it later using some software like Illustrator for final printing.