Resizing canvas to aspect ratio

[d-light]

Please, would add a function "resize canvas to aspect ratio ..."? (Not croping!)
For example I have an image with aspect ratio 16:9 and I need to change the ratio to 4:3. To do this, I have to add strips on top and bottom of the image. So, I choose "change canvas size" and manually calculate the required height by dividing the width by 1,33333.
And please add the ability to choose the background color when resizing the canvas size.
Sorry, for my English)