I'm not sure I quite understand the question.
At the basic HTML/CSS level then you are right. If the code specifies a certain height and width it should be displayed at that size.
However, in the more practical world there's a number of things that can confuse the issue. For a start what units are you using to define the size of the image.
You may be using % of the width or height of the image and that will be constrained by the surrounding code. So, for example, if the image is within a <div> that is defined as being of width 50%, then an image of 100% width will occupy 100% of the available space and that will be the 50% to which the <div> is limited.
On top of that there's all kinds of CSS code that will change things too, like whether overflow is allowed within sections of the code.
I don't use the Summernote editor, but I also recall that using that to install images can also produce results that the non-coder may be surprised by.
In short, we need to know a little more about what you are doing. Perhaps providing a link to a temporary page on your site that exhibits the problem you are having would help folk who might be able to advise you.
