How to read image byte while rendering chart?

Reading a chart as a Stream of byte, and save it in image format while rendering can be  achieved by using the following codes. An FileStream supports both read and write operations. In this example, the chart is read as a Stream of bytes and saved  as an image. The RenderTargetBitmap class specifies the target chart width, height, and pixel of image in pixel format. The PngBitmapEncoder encodes the image to PNG Format. After the chart has been renderd, if we click the button, the chart image will be generated in the bin > debug folder.

C#