When merging images into a Word document there is no way to control the size of the image when the merged image is of an unknown size. The merged image is resized to be the same dimensions as the placeholder image which means that more often than not you end up with an image with the wrong aspect ratio.

It would be useful if, when merging an image, you can nominate a height or width. DocGen could then resize the image to fit the height/width and preserves the aspect ratio by setting the relevant width/height.