[4.1图像处理概述](4.1%E5%9B%BE%E5%83%8F%E5%A4%84%E7%90%86%E6%A6%82%E8%BF%B0.md) [4.2创建图像和销毁图像](4.2%E5%88%9B%E5%BB%BA%E5%9B%BE%E5%83%8F%E5%92%8C%E9%94%80%E6%AF%81%E5%9B%BE%E5%83%8F.md) [4.3图像操作](4.3%E5%9B%BE%E5%83%8F%E6%93%8D%E4%BD%9C.md) [4.4实例：图像验证码](4.4%E5%AE%9E%E4%BE%8B%EF%BC%9A%E5%9B%BE%E5%83%8F%E9%AA%8C%E8%AF%81%E7%A0%81.md) [4.5实例：往图像上写入一行汉字](4.5%E5%AE%9E%E4%BE%8B%EF%BC%9A%E5%BE%80%E5%9B%BE%E5%83%8F%E4%B8%8A%E5%86%99%E5%85%A5%E4%B8%80%E8%A1%8C%E6%B1%89%E5%AD%97.md) [4.6实例：制作图像水印效果](4.6%E5%AE%9E%E4%BE%8B%EF%BC%9A%E5%88%B6%E4%BD%9C%E5%9B%BE%E5%83%8F%E6%B0%B4%E5%8D%B0%E6%95%88%E6%9E%9C.md) [4.7实例：生成图像缩略图](4.7%E5%AE%9E%E4%BE%8B%EF%BC%9A%E7%94%9F%E6%88%90%E5%9B%BE%E5%83%8F%E7%BC%A9%E7%95%A5%E5%9B%BE.md) [4.8文件上传](4.8%E6%96%87%E4%BB%B6%E4%B8%8A%E4%BC%A0.md) [4.9实例：单个文件上传](4.9%E5%AE%9E%E4%BE%8B%EF%BC%9A%E5%8D%95%E4%B8%AA%E6%96%87%E4%BB%B6%E4%B8%8A%E4%BC%A0.md) [4.10实例：多个文件上传](4.10%E5%AE%9E%E4%BE%8B%EF%BC%9A%E5%A4%9A%E4%B8%AA%E6%96%87%E4%BB%B6%E4%B8%8A%E4%BC%A0.md)