In order to get the correct slider background image sizes, please follow the steps below.

Step 1:

Please import Slider Revolution Samples from Dashboard > Vamtam > Quick Import (if you've already done that, please skip the step)

Step 2: 

Please go to Dashboard > Slider Revolution > hit the Settings button of the slider you'd like to get the correct background image sizes from:

Step 3: 

Check or edit the Layers Grid Size (Grid Width and Grid Height)

If the slider width is set to 100% note that images should be at least 1920px width, preferably 3200px in order to cover all resolutions.

If your slider will never scale past 1200px, as shown in the picture above, here’s the mathematical equation for how images will be resized:

Image Width = Slider Width
Image Height = Grid Height * (Slider Width / Grid Width)

Based on the above equation, if your slider’s actual width is 1200px (the width of the slider when displayed on your web page), with an image size of 1000×500, and a “Layer Grid Size” of 1000×500, the image would be resized to 1200×600.

A common question once images are resized is: “Why are my images being cropped and some portions of the image can’t be seen?” The answer is based on the math equation above. Unless the image’s original size is equal the the slider’s “Layers Grid Size”, the image will need to be stretched and cropped. To avoid this, set your slider’s “Layers Grid Size” to equal the exact size of your image’s original size.

We recommend you to check this article for the ideal image size: