Cannot find symbol compiler error

Question

I'm having problems with this assignment I have to do for my java programming class. What I have to do is perform a chroma key technique on an image with a solid background. More info can be found here. The method I created works when I put the two object parameters for the method. But, when I put the parameters in the constructor and then try to use the method, I get a compiler error. I have my class down below (I have to use two different classes, one for methods, one for testing). Any help would be appreciated, I'm new to java and the most simple route would be best.

public class ChromaKey
{
    public ChromaKey(Picture backgroundDelete, Picture backgroundImage)
    {  
    }
    public void chromaKey()
    {        
         int redValue = 0; int greenValue = 0; int blueValue = 0;      
        Color pixelColor = null;   
        Color pixelColor1 = null;   
        for(int y = 0; y < backgroundImage.getHeight(); y++)             
        {
            for(int x = 0; x < backgroundImage.getWidth(); x++)    
            {
                Pixel targetPixel = new Pixel(backgroundImage,x,y);   
                Pixel targetPixel1 = new Pixel(backgroundDelete,x,y);

                targetPixel = backgroundImage.getPixel(x,y);                
                pixelColor = targetPixel.getColor();

                targetPixel1 = backgroundDelete.getPixel(x,y);
                pixelColor1 = targetPixel1.getColor();

                int targetRed = pixelColor1.getRed();
                int targetBlue = pixelColor1.getGreen();
                int targetGreen = pixelColor1.getBlue();

                int backgroundRed = pixelColor.getRed();
                int backgroundGreen = pixelColor.getGreen();
                int backgroundBlue = pixelColor.getBlue();

                if(targetRed >= 200 && targetBlue >= 200 && targetGreen >= 200) 
                {
                    targetPixel1.setRed(backgroundRed);
                    targetPixel1.setGreen(backgroundGreen);
                    targetPixel1.setBlue(backgroundBlue);

                }
            }
        }
        backgroundImage.show();
        backgroundDelete.show();
    }
}

Answer 1

There's a few things that look like they're missing. First of all, are you importing the Color and Pixel classes, or are they included in the same package as your ChromaKey class?

Second, you need to define backgroundImage and backgroundDelete as a class variable in order to call it in your void chromaKey() method (notice "private Picture backgroundDelete;" line I added, along with the assignment in your constructor):

public class ChromaKey {

private Picture backgroundDelete;
private Picture backgroundImage;


public ChromaKey(Picture backgroundDelete, Picture backgroundImage)
{  
    this.backgroundDelete = backgroundDelete;
    this.backgroundImage = backgroundImage;
}
public void chromaKey()
{        
     int redValue = 0; int greenValue = 0; int blueValue = 0;      
    Color pixelColor = null;   
    Color pixelColor1 = null;   
    for(int y = 0; y < backgroundImage.getHeight(); y++)             
    {
        for(int x = 0; x < backgroundImage.getWidth(); x++)    
        {
            Pixel targetPixel = new Pixel(backgroundImage,x,y);   
            Pixel targetPixel1 = new Pixel(backgroundDelete,x,y);

            targetPixel = backgroundImage.getPixel(x,y);                
            pixelColor = targetPixel.getColor();

            targetPixel1 = backgroundDelete.getPixel(x,y);
            pixelColor1 = targetPixel1.getColor();

            int targetRed = pixelColor1.getRed();
            int targetBlue = pixelColor1.getGreen();
            int targetGreen = pixelColor1.getBlue();

            int backgroundRed = pixelColor.getRed();
            int backgroundGreen = pixelColor.getGreen();
            int backgroundBlue = pixelColor.getBlue();

            if(targetRed >= 200 && targetBlue >= 200 && targetGreen >= 200) 
            {
                targetPixel1.setRed(backgroundRed);
                targetPixel1.setGreen(backgroundGreen);
                targetPixel1.setBlue(backgroundBlue);

            }
        }
    }
    backgroundImage.show();
    backgroundDelete.show();
}

}