使用GDI +和C#更改图像对比度 [英] Changing image contrast with GDI+ and C#

问题描述

我的问题如下:

我正在制作一个程序，该程序可以通过C#代码操纵亮度，伽玛和对比度.对于亮度和伽玛，可以.我已经通过网上找到的代码实现了这一目标，但是我无法形成对比.

I am making a program, which can manipulate brightness, gamma and contrast through C# code. For brightness and gamma it is OK. I have achieved it through code I found in the net, but I can't for contrast.

我到目前为止唯一发现的是一个CalculateRamp方法，该方法具有输入参数(double level, double brightness, double gamma, double contrast).我知道要为亮度，伽玛和对比度(界面中滑块的值)提供什么输入，但是我不知道该输入什么水平.

The only thing I have found by now is a CalculateRamp method, which has as input parameters (double level, double brightness, double gamma, double contrast). I know what input to give for brightness, gamma and contrast (the values from the sliders in the interface), but I don't know what level is for.

此方法的另一个问题是，当我将带有随机level参数的计算得出的渐变作为参数传递给SetDeviceGammaRamp(IntPtr hDC,ref RAMP rmp)时，它实际上会改变屏幕对比度，但是当我移动亮度滑块时，对比度会产生变化滑块丢失.可能是因为使用了相同的方法，或者我不确定是什么原因.

The other problem with this method is that when I pass the calculated ramp with random level parameter as a parameter to SetDeviceGammaRamp(IntPtr hDC,ref RAMP rmp) it actually changes the screen contrast, but when I move the brightness slider the changes made from the contrast slider are lost. It may be because of using the same method or I am not sure for what.

我将非常感谢您提供的任何帮助或想法，无论它们是对当前解决方案的更改(还是不完整的解决方案)还是全新的解决方案(我希望这样做)，因为我对此有些不确定.预先感谢大家.

I will be very thankful to any help or ideas, no matter if they are changes to my current solution which is not full, or a brand new solution - which I would prefer - because I feel in some way unsure with this. Thanks in advance to everybody.

这是CalculateRamp方法的代码，因为我调用了函数SetDeviceGammaRamp(...)，以使用当前计算出的斜率来操纵对比度.我不确定是否必须以这种方式使用它:

Here is the code of the CalculateRamp method, as the function SetDeviceGammaRamp(...) is called by me to manipulate the contrast with the current calculated ramp. I am not sure if I have to use it in this way or not:

public static void CalculateRamp(double level, double gamma, double brightness, double contrast)
{
    ramp.Red = new ushort[256];
    ramp.Green = new ushort[256];
    ramp.Blue = new ushort[256];

    gamma /= 10;
    brightness = 1 + (((brightness - 50) / 100) * 65535);
    contrast = 1 + ((contrast - 50) / 100);
    level = 1 + ((level - 50) / 100);

    for (int i = 0; i < 256; i++)
    {
        double value = i * 256;
        value = (Math.Pow(value / 65535, 1 / gamma) * 65535) + 0.5;
        value = ((((value / 65535) - 0.5) * contrast) + 0.5) * 65535;
        value = value += brightness;
        value *= level;
        ramp.Red[i] = ramp.Green[i] = ramp.Blue[i] = (ushort)Math.Min((double)65535, Math.Max((double)0, value));
    }
    SetDeviceGammaRamp(GetDC(IntPtr.Zero), ref ramp);
}

推荐答案

尝试看看

Try taking a look at this article. Its a color matrix which shows how to manipulate both the brightness and the contrast.

本文也许也会引起您的兴趣，尽管我认为本文中使用的方法要比矩阵慢.

This article might also interest you, though I think the method used in this article is slower then the matrix.

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