如何做网站的营销小程序推广引流
目录
前言:
一、色相(Hue)
二、饱和度(Saturation)
三、明度(Lightness)
四、全代码实现
五、效果对比
前言:
PS中的色相/饱和度调节界面可通过快捷键Ctrl+U快速打开,如下
而饱和度和明度调整,PS中的处理并不像平常的单一图像处理,而是做了一些算法改变,接下来就是详细拆分这其中的原理。
一、色相(Hue)
色相的处理就没有那么多的弯弯绕绕了,只需要将RGB转化为HSV,根据值设置H的变化,在转化会RGB即可。原本PS中的色相/饱和度处理面板是对HSL空间的处理,照理说是需要转换到HSL空间的,但对于色相来说,HSV和HSL都是一致的,所以并不需要我们真正的转到HSL。
代码:
// RGB转HSV/HSBhalf3 RGB2HSV(half3 c){half4 K = half4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);half4 P = lerp(half4(c.bg, K.wz), half4(c.gb, K.xy), step(c.b, c.g));half4 Q = lerp(half4(P.xyw, c.r), half4(c.r, P.yzx), step(P.x, c.r));half D = Q.x - min(Q.w, Q.y);half E = 1e-10;return half3(abs(Q.z + (Q.w - Q.y) / (6.0 * D + E)), D / (Q.x + E), Q.x);}// HSV/HSB转RGBhalf3 HSV2RGB(half3 c){half4 K = half4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);half3 P = abs(frac(c.xxx + K.xyz) * 6.0 - K.www);return c.z * lerp(K.xxx, saturate(P - K.xxx), c.y);}
//Huehalf3 hsv = RGB2HSV(color.rgb);hsv.x = frac(hsv.x + _Hue / 360.0);color.rgb = HSV2RGB(hsv);
二、饱和度(Saturation)
饱和度本身在图像处理中就是根据灰度来处理的,但在PS中却设置了许多其它条件,其算法原理如下操作:
(注意,以下原理只使用RGB颜色空间,Lab颜色将不适用此公式)
对每个像素点:
rgbMax=max(R,G,B);
rgbMin=min(R,G,B);
delta=(rgbMax-rgbMin)/255
如果delta=0,则此像素点不再进行处理,而是跳出,进行下一个像素点颜色操作
如果delta>0,则value=(rgbMax+rgbMin)/255
HSL中的L:L=value/2;
HSL中的S:如果L<0.5,S=delta/value;
如果L>=0.5,S=delta/(2-value)
percent = 饱和度调整参数/100【将其归一化到(-1,1)】
如果percent>=0,先求出alpha:
如果percent+S>=1:alpha=S;
否则:alpha=1-percent;
alpha=1/alpha-1;
final_rgb = RGB+(RGB-L*255)*alpha;
如果percent<0,alpha=percent
final_rgb = L*255+(RGB-L*255)*(1+alpha);
解释:其中rgbMax是指传入颜色RGB中最大值
rgbMin是指传入颜色RGB中最小值
percent是指饱和度调整参数归一化后的值(参数在PS的范围是(-100,100))
Shader代码:
half3 Saturation(half3 color, float saturation){half rgbMax = max(color.r, max(color.g, color.b));half rgbMin = min(color.r, min(color.g, color.b));half delta = rgbMax - rgbMin;if (delta > 0){half value = rgbMax + rgbMin;half L = value * 0.5;half S = lerp(delta / value, delta / (2.0 - value), step(0.5, delta));half percent = saturation * 0.01;half alpha = 0;half3 final_color = 0;if (percent >= 0){if (percent + S >= 1)alpha = S;elsealpha = 1 - percent;alpha = 1 / alpha - 1;final_color = color + (color - half3(L, L, L)) * alpha;}else{alpha = percent;final_color = L + (color - half3(L, L, L)) * (1 + alpha);}return final_color;}elsereturn color;}
优化算法:
half3 Saturation(half3 color, float saturation){half rgbMax = max(color.r, max(color.g, color.b));half rgbMin = min(color.r, min(color.g, color.b));half delta = rgbMax - rgbMin;half value = rgbMax + rgbMin;half L = value * 0.5;half S = lerp(delta / value, delta / (2.0 - value), step(0.5, delta));half percent = saturation * 0.01;half3 final_color = lerp(L + (color - L.xxx) * (1 + percent),color + (color - L.xxx) * (1.0 / (lerp(1.0 - percent, S, step(1.0, percent + S))) - 1.0),step(0.0, percent));final_color = lerp(color, final_color, ceil(delta));return final_color;}
函数调用
//Saturationcolor.rgb = Saturation(color.rgb, _Saturation);
三、明度(Lightness)
PS的明度不是指代HSV中的Value和HSB中的Brightness,它也是不线性的单一乘法。实际上,PS的明度调整采用的是Alpha遮罩模式。明度正调整是以一张白色遮罩层进行操作,负调整则是黑色遮罩层。其公式如下:
(注意,以下原理只使用RGB颜色空间,Lab颜色将不适用此公式)
alpha=_Lightness/100【对alpha进行归一化,范围为(-1,1)】
如果_Lightness>0:
final_color = RGB*(1-alpha)+255*alpha;
如果_Lightness<0:
final_color = RGB+RGB*alpha;
解释:其中255代表白色,255*alpha就代表是白色遮罩层,明度越大,遮罩层alpha越大
当alpha<0时则是已黑色遮罩层进行计算,alpha=-1时则是全黑
当且仅当alpha=0时显示的是原图片
Shader代码:
//Valuehalf value = _Lightness * 0.01;if (value > 0)color.rgb = (1 - value) * color.rgb + half3(1.0, 1.0, 1.0) * value;else if (value < 0)color.rgb = color.rgb * (1.0 + value);
优化算法:
color.rgb = lerp(color.rgb * (1.0 + value), lerp(color.rgb, half3(1.0, 1.0, 1.0), value), step(0.0, _Lightness));
四、全代码实现
Shader "Background_Custom_HSV"
{Properties{_PatternTex ("贴图", 2D) = "black" { }[Header(BaseColor)][Space][HDR]_Color0 ("颜色", Color) = (1, 1, 1, 1)[Header(HSL)][Space]_Hue ("Hue", Range(-180, 180)) = 0.0_Saturation ("Saturation", Range(-100, 100)) = 0.0_Lightness ("Lightness", Range(-100, 100)) = 0.0}SubShader{Tags { "RenderType" = "Transparent" "Queue" = "Transparent" "RenderPipeline" = "UniversalPipeline" "IgnoreProjector" = "True" }Pass{Blend SrcAlpha OneMinusSrcAlphaZWrite OffCull BackHLSLPROGRAM#pragma vertex vert#pragma fragment frag#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"TEXTURE2D(_PatternTex);SAMPLER(sampler_PatternTex);CBUFFER_START(UnityPerMaterial)half3 _Color0;float _Hue;float _Saturation;float _Lightness;CBUFFER_ENDstruct Attributes{float4 positionOS : POSITION;float2 texcoord : TEXCOORD0;};struct Varyings{float4 positionHS : SV_POSITION;float2 uv : TEXCOORD0;};// RGB转HSV/HSBhalf3 RGB2HSV(half3 c){half4 K = half4(0.0, -1.0 / 3.0, 2.0 / 3.0, -1.0);half4 P = lerp(half4(c.bg, K.wz), half4(c.gb, K.xy), step(c.b, c.g));half4 Q = lerp(half4(P.xyw, c.r), half4(c.r, P.yzx), step(P.x, c.r));half D = Q.x - min(Q.w, Q.y);half E = 1e-10;return half3(abs(Q.z + (Q.w - Q.y) / (6.0 * D + E)), D / (Q.x + E), Q.x);}// HSV/HSB转RGBhalf3 HSV2RGB(half3 c){half4 K = half4(1.0, 2.0 / 3.0, 1.0 / 3.0, 3.0);half3 P = abs(frac(c.xxx + K.xyz) * 6.0 - K.www);return c.z * lerp(K.xxx, saturate(P - K.xxx), c.y);}half3 Saturation(half3 color, float saturation){half rgbMax = max(color.r, max(color.g, color.b));half rgbMin = min(color.r, min(color.g, color.b));half delta = rgbMax - rgbMin;// if (delta > 0)// {// half value = rgbMax + rgbMin;// half L = value * 0.5;// half S = lerp(delta / value, delta / (2.0 - value), step(0.5, delta));// half percent = saturation * 0.01;// half alpha = 0;// half3 final_color = 0;// if (percent >= 0)// {// if (percent + S >= 1)// alpha = S;// else// alpha = 1 - percent;// alpha = 1 / alpha - 1;// final_color = color + (color - half3(L, L, L)) * alpha;// }// else// {// alpha = percent;// final_color = L + (color - half3(L, L, L)) * (1 + alpha);// }// return final_color;// }// else// return color;half value = rgbMax + rgbMin;half L = value * 0.5;half S = lerp(delta / value, delta / (2.0 - value), step(0.5, delta));half percent = saturation * 0.01;half3 final_color = lerp(L + (color - L.xxx) * (1 + percent),color + (color - L.xxx) * (1.0 / (lerp(1.0 - percent, S, step(1.0, percent + S))) - 1.0),step(0.0, percent));final_color = lerp(color, final_color, ceil(delta));return final_color;}Varyings vert(Attributes v){Varyings o;o.positionHS = TransformObjectToHClip(v.positionOS.xyz);o.uv = v.texcoord;return o;}half4 frag(Varyings i) : SV_Target{half4 color = SAMPLE_TEXTURE2D(_PatternTex, sampler_PatternTex, i.uv);color.rgb *= _Color0.rgb;//Huehalf3 hsv = RGB2HSV(color.rgb);hsv.x = frac(hsv.x + _Hue / 360.0);color.rgb = HSV2RGB(hsv);//Saturationcolor.rgb = Saturation(color.rgb, _Saturation);//Valuehalf value = _Lightness * 0.01;// if (value > 0)// color.rgb = (1 - value) * color.rgb + half3(1.0, 1.0, 1.0) * value;// else if (value < 0)// color.rgb = color.rgb * (1.0 + value);color.rgb = lerp(color.rgb * (1.0 + value), lerp(color.rgb, half3(1.0, 1.0, 1.0), value), step(0.0, _Lightness));color.rgb = saturate(color.rgb);return color;}ENDHLSL}}FallBack "Hidden/Universal Render Pipeline/FallbackError"
}
五、效果对比
基础色:
色相:
饱和度:
明度: