The picture need more space of bytes, because may be it has higher resolution or image quality, usually the big resolution and higher quality is made from a digital camera, to resize it smaller size and smaller byte, you can use paint if you are using Windows from Microsoft.
Go to paint, hit CTRL+A, then CTRL-W. You can resize it a half smaller or more.
And save it as PNG or JPG or JPEG extension. Dont save it as BMP because it require more space.
