The css background properties allow you to control the background color of an element , set an image as the background , repeat a background image vertically or horizontally , and position an image on a page Css背景属性允许你控制元素的背景颜色，设置一图片做为背景，垂直或水平的重复背景图片，和图片在页面上的位置。
Note ： to use style3 , customize toolbar , set the " offline " and " bg color " icons as the first and second icon on toolbar ( note , the " forward " and " backward " icons on toolbar in style3 is just backgroup image , you should use mouse action to browse forward and backward 注意，风格3中前进后退只是背景图片，用时，自定义工具栏，把脱机工作和设背景色摆在工具栏的最前面，前进后退就用鼠标手势来控制吧。
Our work is focused on the image processing module ( ipm ) , where license locating and character recognition are realised . to locate the license plate , we take the two - step strategy . in the first step , the static background is extracted , as a result , a general car picture is got . in the second step , the license plate is located accurately . in step one , the backgroud picture is dynatically fixed . the substraction between car image and background image is redefined to make the proess more effectively 首先，从图片中消除静止的背景图像，得到汽车的模糊轮廓；其次，实现牌照的第二次定位，即实现牌照的精确定位。在牌照的初步定位中，我们采取了将动态确定背景图片，将待识图片和背景图片相减的方法。在图片相减过程中，提出了自己的改进方法，简化运算，提高了效率。
