Vector image is a type of image composed of many geometric primitives. Compared with bitmaps, vector images have the ability to save memory as well as to enlarge without distortion. Meanwhile, it has been commonly adopted in data visualization (image data) because it can be scaled to multiple sizes to fit different scenes. For instance, it can be applied for the illustrations in newspapers and magazines, the logo on the web, the background for poster, the design of text, and traffic signs. However, transforming a bitmap to vector image is still a challenging problem because of the complicated content of a bitmap, which tends to consist of more than just simple geometry. Aiming at this issue, there is a new approach proposed to transform from bitmaps to vector images, which is based on triangle units and consists of three steps. In detail, firstly, there is an initial mesh constructed for one image in pixel level after detecting features. Then, the initial mesh will be simplified by collapsing two vertices as the initial mesh is too dense to represent one image. Specifically, there are two main parts in this step, which are collapse conditions and collapse influences. In the step of collapsing, issues such as overlap and sharp triangles can be conquered by a sort-edge method (which will be illustrated specifically later). The final step is to select one color for each triangle, since it is helpful to save the memory and speed up the process of this method. In addition, one color will represent one triangle; hence, in the final step, the four-triangle sample method will be applied in order to prevent a vector image from generating too large color discontinuity. Once the pretest proceeds without mistake, the method above is able to work for the general bitmaps. Note that our method can be applied to information security and privacy, since one image can be encoded to some triangles and colors.

中文翻译：

---

考虑图像三角剖分和颜色选择的将位图转换为矢量图像以实现数据可靠可视化的新方法

矢量图像是由许多几何图元组成的一种图像。与位图相比，矢量图像具有节省内存以及在不失真的情况下进行放大的能力。同时，它可以在数据可视化（图像数据）中普遍采用，因为它可以缩放到多种大小以适合不同的场景。例如，它可以用于报纸和杂志上的插图，网络上的徽标，海报的背景，文本的设计以及交通标志。然而，由于位图的复杂内容，将位图转换为矢量图像仍然是一个具有挑战性的问题，它往往不仅仅是简单的几何图形。针对这个问题，提出了一种新的方法，该方法基于三角形单位并由三个步骤组成，该方法可以将位图转换为矢量图像。首先，在检测到特征后，会为一个像素级的图像构建一个初始网格。然后，由于初始网格过于密集而无法表示一个图像，因此可以通过折叠两个顶点来简化初始网格。具体而言，此步骤有两个主要部分，分别是崩溃条件和崩溃影响。在折叠步骤中，可以通过排序边缘方法（稍后将具体说明）解决诸如重叠和尖锐三角形之类的问题。最后一步是为每个三角形选择一种颜色，因为这有助于节省内存并加快此方法的处理。另外，一种颜色代表一个三角形；另一种颜色代表一个三角形。因此，在最后一步中，将采用四三角形采样方法，以防止矢量图像产生太大的颜色不连续性。一旦进行了正确的预测试，上述方法就可以用于常规位图。请注意，我们的方法可以应用于信息安全和隐私，因为一个图像可以被编码为一些三角形和颜色。