hlsl pixel shader-更改特定色调的图像颜色

看看 "post RGB to HSV" sample over at the NVidia Shader Library page . 这可能会给你一些灵感。

否则,我想你可以“简单”地将一个RGB颜色转换为HSV在你的像素着色中使用 the formula from Wikipedia 然后从那里拿走。

制作一个围绕[1,1,1]轴(亮度轴)*旋转RGB颜色的矩阵,旋转角度将源颜色旋转到目标颜色。将此矩阵设置为像素着色常量。

在像素明暗器中,通过该矩阵变换像素颜色。然后,根据未转换像素的色调和源颜色的色调之间的角度,在未转换和转换的颜色之间进行LERP。当角度很小时,使用转换后的颜色。当角度较大时,使用未转换的颜色。

要确定像素的色调,请从像素中减去其RGB*的平均值。这个向量和[1,0,0]之间的角度就是色调。

*我知道亮度并不是那么简单,但对于这种情况,这是一个足够好的近似值。

看一看

• http://www.nathanm.com/photoshop-blending-math/
• http://mouaif.wordpress.com/2009/01/05/photoshop-math-with-glsl-shaders/

色调/饱和度/亮度/对比度HLSL像素明暗器(shazzam.fx)

/// <class>7Aliens HSBC Hue/Saturation/Brightness/Contrast</class>
/// <description>Blend modes Brightness/Contrast (Photoshop CS) with Hue and Saturation.</description>

sampler2D input : register(s0);

/// <summary>The brightness offset.</summary>
/// <minValue>-2</minValue>
/// <maxValue>2</maxValue>
/// <defaultValue>0</defaultValue>
float SliderBrightnes : register(C0);

/// <summary>The brightness offset.</summary> 
/// <minValue>-1</minValue>
/// <maxValue>1</maxValue>
/// <defaultValue>0</defaultValue>
float SliderContrast : register(C1);

/// <summary>The brightness offset.</summary>
/// <minValue>-1</minValue>
/// <maxValue>1</maxValue>
/// <defaultValue>0</defaultValue>
float sliderSaturation : register(C2);

/// <summary>The brightness offset.</summary>
/// <minValue>-180</minValue>
/// <maxValue>180</maxValue>
/// <defaultValue>0</defaultValue>
float sliderHue : register(C3);

float3x3 QuaternionToMatrix(float4 quat)
{
    float3 cross = quat.yzx * quat.zxy;
    float3 square= quat.xyz * quat.xyz;
    float3 wimag = quat.w * quat.xyz;

    square = square.xyz + square.yzx;

    float3 diag = 0.5 - square;
    float3 a = (cross + wimag);
    float3 b = (cross - wimag);

    return float3x3(
    2.0 * float3(diag.x, b.z, a.y),
    2.0 * float3(a.z, diag.y, b.x),
    2.0 * float3(b.y, a.x, diag.z));
}

const float3 lumCoeff = float3(0.2125, 0.7154, 0.0721);

float4 Desaturate(float3 color, float Desaturation)
{
    float3 grayXfer = float3(0.3, 0.59, 0.11);
    float grayf = dot(grayXfer, color);
    float3 gray = float3(grayf, grayf, grayf);
    return float4(lerp(color, gray, Desaturation), 1.0);
}

float4 main(float2 uv : TEXCOORD) : COLOR 
{ 
    float4  cInput; 
    cInput = tex2D( input , uv.xy);

    float4 inputColor;
    inputColor = cInput;
    float4 blendColor;
    blendColor = cInput;
    float4 resultColor;
    resultColor = cInput;

    float3 hsv; 
    float3 intensity;           
    float3 root3 = float3(0.57735, 0.57735, 0.57735);
    float half_angle = 0.5 * radians(sliderHue); // Hue is radians of 0 tp 360 degree
    float4 rot_quat = float4( (root3 * sin(half_angle)), cos(half_angle));
    float3x3 rot_Matrix = QuaternionToMatrix(rot_quat);     
    resultColor.rgb = mul(rot_Matrix, inputColor.rgb);

    resultColor = Desaturate(resultColor, -sliderSaturation);

    inputColor = resultColor;`enter code here`
    blendColor = resultColor;
    resultColor = resultColor;

    blendColor.rgb = clamp(blendColor.rgb / blendColor.a, 0, 1);
    if (resultColor.r > 0.5) resultColor.r = 1 - (1 - 2 * (resultColor.r - 0.5)) * (1 - blendColor.r); else resultColor.r = (2 * resultColor.r) * blendColor.r;
    if (resultColor.g > 0.5) resultColor.g = 1 - (1 - 2 * (resultColor.g - 0.5)) * (1 - blendColor.g); else resultColor.g = (2 * resultColor.g) * blendColor.g;
    if (resultColor.b > 0.5) resultColor.b = 1 - (1 - 2 * (resultColor.b - 0.5)) * (1 - blendColor.b); else resultColor.b = (2 * resultColor.b) * blendColor.b;

    float4 colorOverlay = resultColor;
    colorOverlay = colorOverlay * SliderContrast;
    resultColor.rgb = (1 - (colorOverlay.a)) * inputColor.rgb + colorOverlay.rgb;       

    inputColor = resultColor;
    blendColor = resultColor;

    float4 colorScreen = resultColor;
    colorScreen.rgb = (1.0f - (1.0f - inputColor.rgb) * (1.0f - blendColor.rgb));
    colorScreen = -(colorScreen * SliderBrightnes * -(1 - inputColor.r));
    resultColor.rgb = (1 - (colorScreen.a)) * inputColor.rgb + colorScreen.rgb;

    return resultColor; 
}