为自定义ShaderEffect创建黑色滤镜 [英] Creating a black filter for a custom ShaderEffect

问题描述

我正在使用此代码示例调整WPF应用程序在BitmapImage上的亮度和对比度. HLSL代码的相关位是这样的:

I am using this code example to adjust brightness and contrast on a BitmapImage for my WPF app. The relevant bit of HLSL code is this:

sampler2D input : register(s0);
float brightness : register(c0);
float contrast : register(c1);

float4 main(float2 uv : TEXCOORD) : COLOR
{
    float4 color = tex2D(input, uv); 
    float4 result = color;
    result = color + brightness;
    result = result * (1.0+contrast)/1.0;

    return result;
}

我想做的是添加一些东西来滤除低强度像素-这个想法是我想说图像的任何部分(我只是猜测我必须对每个像素执行此操作)都在一定的阈值，使其变黑.我正在尝试滤除灰色的低强度材料，以使较亮的部分弹出得更多(这是灰度图像).然后，我将使用滑块来调整该阈值.

What I would like to do is add something to filter out low intensity pixels- the idea is that I want to say that any part of the image (I'm just guessing I have to do this per pixel) is below a certain threshold, make it black. I'm trying to filter out greys a low intensity stuff to make the lighter parts pop out more (this is a greyscale image). I would then use a slider to adjust that threshold.

我只是不知道这是一个过滤器还是什么，原本希望它只是上面代码的简单mod.总计HLSL为n00b.

I just have no idea if this is a filter or what, was was hoping it's just a simple mod to the code above. Total n00b to HLSL.

推荐答案

尝试一下:

sampler2D input : register(s0);
float threshold : register(c0);
float4 blankColor : register(c1);

float4 main(float2 uv : TEXCOORD) : COLOR
{
    float4 color = tex2D(input, uv);
    float intensity = (color.r + color.g + color.b) / 3;

    float4 result;
    if (intensity < threshold)
    {
        result = blankColor;
    }
    else
    {
        result = color;
    }

    return result;
}

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