Color Section Parralax Image Width

I’m trying to use an image 1130px x 400px as the color-section background image, while using the parallax feature. However, each time I set the image and refresh the page, the image seems to be scaled to a larger size. What size does the image need to be so that it isn’t scaled at all. Also, shouldn’t the option “stretch to fit” take care of this issue? Thank you.

Note: I have tried multiple thumbnail sizes when setting the image.