How to open an image with ImageJ in java

Question

I want to analyse images using the ImageJ framework in java. How can I open an image? I need to have an ImageProcessor object to be able to generate a histogram. Here is the code I have so far:

public void run(ImageProcessor ip) {
        int[] H = new int[256]; // histogram array
        int w = ip.getWidth();
        int h = ip.getHeight();

        for (int v = 0; v < h; v++) {
            for (int u = 0; u < w; u++) {
                int i = ip.getPixel(u, v);
                H[i] = H[i] + 1;
            }
        }

        // ... histogram H[] can now be used
    }

Answer 1

I work with medical grayscale images where a ColorProcesser is not appropriate. In that case I use

Opener opener = new Opener();  
String imageFilePath = "somePath";
ImagePlus imp = opener.openImage(imageFilePath);
ImageProcesser ip = imp.getProcessor(); // ImageProcessor from ImagePlus