Question

import java.awt.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.ImageIO;


public class ConvertRGBtoLAB {


    public static void main(String[] args) {

      //get input image
     String fileName = "IMG_7990.jpg";
     //read input image
     BufferedImage image = null;
        try
        {
            image = ImageIO.read(new File(fileName));
        }
        catch (IOException e)
        {
            e.printStackTrace();
        }


        //setup result image
        int sizeX = image.getWidth();
        int sizeY = image.getHeight();


                float r, g, b, X, Y, Z, fx, fy, fz, xr, yr, zr;
  float ls, as, bs;
  float eps = 216.f/24389.f;
  float k = 24389.f/27.f;

  float Xr = 0.964221f;  // reference white D50
  float Yr = 1.0f;
  float Zr = 0.825211f;

                for (int y = 0; y < image.getHeight(); y++) {
            for (int x = 0; x < image.getWidth(); x++) {
                int c = image.getRGB(x,y);
                int  R= (c & 0x00ff0000) >> 16;
                int  G = (c & 0x0000ff00) >> 8;
                int  B = c & 0x000000ff;

                 r = R/255.f; //R 0..1
  g = G/255.f; //G 0..1
  b = B/255.f; //B 0..1

  // assuming sRGB (D65)
  if (r <= 0.04045)
   r = r/12;
  else
   r = (float) Math.pow((r+0.055)/1.055,2.4);

  if (g <= 0.04045)
   g = g/12;
  else
   g = (float) Math.pow((g+0.055)/1.055,2.4);

  if (b <= 0.04045)
   b = b/12;
  else
   b = (float) Math.pow((b+0.055)/1.055,2.4);


  X =  0.436052025f*r     + 0.385081593f*g + 0.143087414f *b;
  Y =  0.222491598f*r     + 0.71688606f *g + 0.060621486f *b;
  Z =  0.013929122f*r     + 0.097097002f*g + 0.71418547f  *b;

  // XYZ to Lab
  xr = X/Xr;
  yr = Y/Yr;
  zr = Z/Zr;

  if ( xr > eps )
   fx =  (float) Math.pow(xr, 1/3.);
  else
   fx = (float) ((k * xr + 16.) / 116.);

  if ( yr > eps )
   fy =  (float) Math.pow(yr, 1/3.);
  else
  fy = (float) ((k * yr + 16.) / 116.);

  if ( zr > eps )
   fz =  (float) Math.pow(zr, 1/3.);
  else
   fz = (float) ((k * zr + 16.) / 116);

  ls = ( 116 * fy ) - 16;
  as = 500*(fx-fy);
  bs = 200*(fy-fz);


                int Ls = (int) (2.55* ls + .5);
                int As = (int) (as + .5);
                int Bs = (int) (bs + .5);

               int lab = 0xFF000000 + (Ls << 16) + (As << 8) + Bs; // and reassign

                image.setRGB(x, y, lab);

          }
        }


        //write new image
         File outputfile = new File("lab.png");
         try {
         // png is an image format (like gif or jpg)
         ImageIO.write(image, "png", outputfile);
         } catch (IOException ex) {
         ex.printStackTrace();
         }


    }


}

您好，

我正在尝试将RGB图像转换为CIELAB颜色空间（LAB）我得到了一个输出，但我不知道它应该是什么样的。

有人能指出我已有的图像转换器或确认我已正确完成此操作吗？

谢谢！

Answer 1

我个人使用this site作为常见颜色空间之间转换公式的快速参考。

Answer 2

OpenCV具有不同颜色空间之间转换的功能。看看我的另一个答案here。这是在C，你可以很容易地检查你的代码。

Answer 3

您需要确保Ls，As和Bs被限制在0到255的范围内。您必须将它们组合成单个int的语句将允许越界值会影响其他值。

RGB到CIELAB转换

3 个答案: