图像加载性能

问题描述

我一直在尝试与不同的方式从文件加载图像几个小时。请看看这两种方法：

I've been experimenting for a few hours with various ways to load an image from file. Please have a look at these two methods:

    public Image SlowLoad(string path)
    {
        return Image.FromFile(path);
    }

    public Image FastLoad(string path)
    {
        using (MemoryStream ms = new MemoryStream(File.ReadAllBytes(path)))
            return Image.FromStream(ms);  
    }

的第二种方法是像快2倍。我缺少的是在这里吗？为什么会这样呢？我不能相信，更快速简单地使用我写的方法.NET开发人员无法实施Image.FromFile。所以=>我错了地方。请告诉我在哪里。为什么第二个方法快了近2倍？是我的代码完全正确吗？ （线程安全等）。 ？也许Image.FromFile是更安全的。

The second method is like 2 times faster. What am I missing here? Why is it so? I can't believe that .NET developers couldn't implement Image.FromFile faster simply using the method I wrote. So => I am wrong somewhere. Please tell me where. Why is the second method almost 2 times faster? Is my code fully correct? (thread-safe, etc.). Maybe Image.FromFile is more secure?

推荐答案

据我所知：
所有Image.FromFile首先包装GDI + GdipLoadImageFromFile *函数，那些有一个奇怪的生活。 GDI +图像的保存，并且可以使用源（文件或流）整个生命周期中，它 http://support.microsoft.com/en-us/kb/814675 。所以，这里是一些可能的多个文件IO与多流IO。
也有在MS参考源为System.Drawing.Image一些有趣的评论：

AFAIK:First of all Image.FromFile wraps GDI+ GdipLoadImageFromFile* functions, ones has a strange life. GDI+ image holds and can use source (file or stream) during whole lifetime, some details about it http://support.microsoft.com/en-us/kb/814675. So, here is some possible "multiple file io" vs "multiple stream io".Also there is some interesting comment in MS Reference Source System.Drawing.Image:

的

class Image {
    ............
    public static Image FromFile(String filename,
                                     bool useEmbeddedColorManagement) 
    {
        ............    
        //GDI+ will read this file multiple times. 
        ............
    }
}

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