将2种RGB颜色与Alpha相结合

Question

当我组合2种颜色时,我正在尝试(在Java中)获得最终颜色,顶部的颜色具有alpha透明度.基本上,我正在尝试为图像指定背景颜色,但我已将其分解为每个单独更改的像素.我看过几篇文章,包括这篇文章,都无济于事.有谁知道如何进行这种RGBA/RGB混色？我目前的代码使用这个png:

并生成这个JPG:

这是我目前正在使用的功能.演示图像的背景设置为全蓝色或int为255.

public static void PNGToJPEGConvert(String PNGPath, String NewJPEGPath, int BackColor) throws IOException {
    try {
        BufferedImage bufferedImage = ImageIO.read(new File(PNGPath));
        BufferedImage newImage;
        int R1, G1, B1, R2 = (BackColor & 0xFF0000) >> 16, G2 = (BackColor & 0xFF00) >> 8, B2 = (BackColor & 0xFF), W1, W2, W3, M1, M2, R3, G3, B3;
        float br;
        newImage = new BufferedImage(bufferedImage.getWidth(), bufferedImage.getHeight(), BufferedImage.TYPE_4BYTE_ABGR);
        for(int x=0; x < bufferedImage.getWidth(); x++) {
            for(int y=0; y < bufferedImage.getHeight(); y++) {
                R1 = BufferedImageGetPixelARGB(bufferedImage, "R", x, y);
                G1 = BufferedImageGetPixelARGB(bufferedImage, "G", x, y);
                B1 = BufferedImageGetPixelARGB(bufferedImage, "B", x, y);
                W1 = Math.min(R1, Math.min(G1, B1));
                W2 = Math.min(R2, Math.min(G2, B2));
                R1 -= W1;
                G1 -= W1;
                B1 -= W1;
                R2 -= W2;
                G2 -= W2;
                M1 = Math.max(R1, Math.max(G1, B1));
                M2 = Math.max(R2, Math.max(G2, B2));
                br = (M1 + M2)/(2*BufferedImageGetPixelARGB(bufferedImage, "A", x, y));
                R3 = (int) ((R1 + R2) * br);
                G3 = (int) ((G1 + G2) * br);
                B3 = (int) ((B1 + B2) * br);
                W3 = (W1 + W2) / 2;
                R3 += W3;
                G3 += W3;
                B3 += W3;
                newImage.setRGB(x, y, RGBValuesToInt(R3, G3, B3));
            }
        }
        try {
            ImageIO.write(newImage, "jpg", new File(NewJPEGPath));
        } catch(Exception e) {

        }
    } catch(Exception e) {

    }
}

谢谢你的帮助,-Neil

Answer 1

public static Color mixColorsWithAlpha(Color color1, Color color2, int alpha)
{
    float factor = alpha / 255f;
    int red = (int) (color1.getRed() * (1 - factor) + color2.getRed() * factor);
    int green = (int) (color1.getGreen() * (1 - factor) + color2.getGreen() * factor);
    int blue = (int) (color1.getBlue() * (1 - factor) + color2.getBlue() * factor);
    return new Color(red, green, blue);
}

这与在color1上绘制color2(具有给定的alpha值)相同.