how to Get stream of the file using C#.net?

hello all how are u??
im using C#.net to do some thing with image by using Bitmap object
assume that my file name is "mypic.png" and i want to get stream of image and then using it in the following code:
Bitmap originalBMP = new Bitmap(file content should be here as a stream , so i need to know how i can do that and getting file stream ? );


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