Add a white background. After that save the file, it has to be PSD otherwise it won't work with the Displace filter.

增加一个白色背景，然后保存文件成PSD格式，否则就不能被置换滤镜操作。

youdao

Finally add a gradient to the sidebar spanning from white to the light grey background to add a little interest and dimension.

最后在侧边栏上添加一个从白色到灰色的渐变来增加些细节和层次。

youdao

I used a mask, and add some white touches in the middle, again according on photo, but this time the one with dark background.

我用蒙版，并在中间添加一些白色触感，再根据照片，但这次放一个黑色背景。

youdao