从Photoshop的色相/饱和度调整层的算法 [英] Algorithm for Hue/Saturation Adjustment Layer from Photoshop

问题描述

有没有人知道调整图层如何在Photoshop中工作？我需要从色相/饱和度调整层生成具有源图像和HSL值的结果图像。

Does anyone know how adjustment layers work in Photoshop? I need to generate a result image having a source image and HSL values from Hue/Saturation adjustment layer. Conversion to RGB and then multiplication with the source color does not work.

或者，可以使用适当设置的混合模式用正常图层替换色相/饱和度调整图层（Mulitiply ，Screen，Hue，Saturation，Color，Luminocity，...）？
如果是，那么如何？

Or is it possible to replace Hue/Saturation Adjustment Layer with normal layers with appropriately set blending modes (Mulitiply, Screen, Hue, Saturation, Color, Luminocity,...)? If so then how?

感谢

推荐答案

当选中Colorize复选框时，我已反向设计的计算。以下所有代码都是伪代码。

I've reverse-engineered the computation for when the "Colorize" checkbox is checked. All of the code below is pseudo-code.

输入是：

HSV（photoshop_hue，100，100）.ToRGB（）为 <$>

• hueRGB code>


• 饱和度，即 photoshop_saturation / 100.0


• lightness ，即 photoshop_lightness / 100.0 （即-1..1）


• value ，这是 pixel.ToHSV（）。Value ，缩放到0..1范围。 li>
  

• hueRGB, which is an RGB color for HSV(photoshop_hue, 100, 100).ToRGB()
• saturation, which is photoshop_saturation / 100.0 (i.e. 0..1)
• lightness, which is photoshop_lightness / 100.0 (i.e. -1..1)
• value, which is the pixel.ToHSV().Value, scaled into 0..1 range.

着色单个像素的方法：

color = blend2(rgb(128, 128, 128), hueRGB, saturation);

if (lightness <= -1)
    return black;
else if (lightness >= 1)
    return white;

else if (lightness >= 0)
    return blend3(black, color, white, 2 * (1 - lightness) * (value - 1) + 1)
else
    return blend3(black, color, white, 2 * (1 + lightness) * (value) - 1)

其中 blend2 和 blend3 分别是：

blend2(left, right, pos):
    return rgb(left.R * (1-pos) + right.R * pos, same for green, same for blue)

blend3(left, main, right, pos):
    if (pos < 0)
        return blend2(left, main, pos + 1)
    else if (pos > 0)
        return blend2(main, right, pos)
    else
        return main

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