如何在循环中初始化位图变量时避免占用过多内存？

Question

I'm making a screen recording program so how it works is that it take a lot of pictures then stores them to make it into a video, but i ran into a problem when making the program run longer than 8 seconds. It uses way more memory than it should.

            while (DateTime.Now.Minute * 60000 + DateTime.Now.Second * 1000 + DateTime.Now.Millisecond < startTime+20000) {
            memoryImage = new Bitmap(ScreenBounds.Width, ScreenBounds.Height);
            // Create graphics 
            Console.WriteLine("Creating Graphics...");
            Console.WriteLine();
            Graphics memoryGraphics = Graphics.FromImage(memoryImage);

            // Copy data from screen 
            Console.WriteLine("Copying data from screen...");
            Console.WriteLine();
            try
            {
                    memoryGraphics.CopyFromScreen(0, 0, 0, 0, ScreenBounds);
            }
            catch (Exception er)
            {
                    Console.WriteLine("Error when copying data from screen error: " + er.Message + " : breaking script");
                    break;
            }

            // Save it! 
            Console.WriteLine("Saving the image...");
            images.Add(memoryImage);
            GC.Collect();
            GC.WaitForFullGCComplete();

As you can see I tried forcing garbage collection; the problem variable is memoryImage or at least that's what it seems to be I'm not completely sure. How can I get this program to use less memory, so it doesn't crash?

UPDATE: I added memoryImage.Dispose(); to the end of the first part which fixed the memory issue but now I get the error:

An unhandled exception of type 'System.ArgumentException' occurred in System.Drawing.dll

Additional information: Parameter is not valid.

in this block of code:

            VideoWriter video = new VideoWriter(@"outputVideo.avi", (int)AvgFPSList.Average(), Screen.PrimaryScreen.Bounds.Size, true);
        for (int x = 0; x < images.Count; x++)
        {
            Image<Emgu.CV.Structure.Bgr, Byte> img = new Image<Emgu.CV.Structure.Bgr, Byte>(images[x]); << error here
            video.Write(img.Mat);
        }

Answer 1

To answer the original question for future viewers,

The Graphics class implements IDisposable. To remove it from memory either wrap it in a using statement or manually call Dispose on it when you are finished using it.

Using example:

using (Graphics memoryGraphics = Graphics.FromImage(memoryImage))
{
    // perform operations on memoryGraphics
}

Bitmap also implements IDisposable and should be properly disposed of at some point.

The authors update of the question may be a different problem.