A quick tip when resizing/editing images.
To resize/edit images the optimum process is to edit prior to importing or do so within the Content section. Resizing in the template or using the drag function can cause the image to render in an unintended size.
To resize an image, go into your campaign and double click the image. This screen should appear, to edit the height and width click the padlock to make it editable. Then readjust your width and height to your preferred size. Having the padlock closed means it will auto size the image to fit the campaign.
To make sure your campaign will render the image correctly, please make sure to previously resize the image in your Content Library.
Navigate to the Content Library via the Insert tab in the toolbar. (You can also access it by dragging in an image block and clicking on that)
Once in the Library, click the drop down menu next to the image you want to resize.#
This will open up the resizing window which gives you the option to pick from four preset sizes (Selected Image, Small Banner, Banner, Thumbnail) as well as allowing you to enter the Height and Width.
Please note that ticking the Constrain Proportions will automatically adjust the Height or Width dependant on which one you enter first. So, if you have a precise size you need to enter, make sure this option is unticked before doing so.