Convert negative image to positive [closed]

Answer 1

I just wrote up a working example. Given the following input image img.png.

The output will be a new image invert-img.png like

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;

class Convert
{
    public static void main(String[] args)
    {
        invertImage("img.png");
    }

    public static void invertImage(String imageName) {
        BufferedImage inputFile = null;
        try {
            inputFile = ImageIO.read(new File(imageName));
        } catch (IOException e) {
            e.printStackTrace();
        }

        for (int x = 0; x < inputFile.getWidth(); x++) {
            for (int y = 0; y < inputFile.getHeight(); y++) {
                int rgba = inputFile.getRGB(x, y);
                Color col = new Color(rgba, true);
                col = new Color(255 - col.getRed(),
                                255 - col.getGreen(),
                                255 - col.getBlue());
                inputFile.setRGB(x, y, col.getRGB());
            }
        }

        try {
            File outputFile = new File("invert-"+imageName);
            ImageIO.write(inputFile, "png", outputFile);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

If you want to create a monochrome image, you can alter the calculation of col to something like this:

int MONO_THRESHOLD = 368;
if (col.getRed() + col.getGreen() + col.getBlue() > MONO_THRESHOLD)
    col = new Color(255, 255, 255);
else
    col = new Color(0, 0, 0);

The above will give you the following image

You can adjust MONO_THRESHOLD to get a more pleasing output. Increasing the number will make the pixel darker and vice versa.

Answer 2

Try LookupOp. Here is a sample from Filthy Rich Clients book.

Answer 3

A head start it is, then. Assuming that you have access to each individual pixel in the negative image, and that each pixel has components RGB, obtain the RGB components of the original pixels like this:

int originalRed   = Math.abs( pixel.getRed( ) - 255 );
int originalGreen = Math.abs( pixel.getGreen( ) - 255 );
int originalBlue  = Math.abs( pixel.getBlue( ) - 255 );
// now build the original pixel using the RGB components

Doing the above for each pixel, you can obtain the original image by recreating it pixel-by-pixel.