Question

I’m doing 2D filteing and want to do element by element addition on grayscale BufferedImages. Is there an existing function that will complete this for me or do i need to make one from scrach?

Is there some sort of matrix class that converts a raster to a matrix to simplyfy this problem?

Edit: here is the general gist of it

    BufferedImageOp opX = new ConvolveOp(new Kernel(3,3, kernelX));
    BufferedImageOp opY = new ConvolveOp(new Kernel(3,3, kernelY));
    BufferedImage filtImageX = opX.filter(sourceImage, null);
    BufferedImage filtImageY = opY.filter(sourceImage, null);
    BufferedImage outputImage = addBufferedImages(filtImageX, filtImageY);

Grayscale Conversion:

public void toGrayscale() { 
     BufferedImageOp op = new ColorConvertOp(ColorSpace.getInstance(ColorSpace.CS_GRAY), null); 
     sourceImage = op.filter(sourceImage, null); 
}

Answer 1

I am not familiar with any java libs that do that for you.

You can get pixel at [i,j] with: image.getRGB(i, j);

BufferedImage image = ...;
BufferedImage resultImage = ...

int rgb= image.getRGB(i, j);
resultImage.setRGB(i, j, rgb);

You can also convert a buffered image to a byte array [ https://stackoverflow.com/a/7388025/1007845 ].
See this thread: how to convert image to byte array in java? to get a WritableRaster

EDIT:

It seems that WritableRaster might be useful in this case: http://docs.oracle.com/javase/1.4.2/docs/api/java/awt/image/WritableRaster.html

WritableRaster raster = image.getRaster();

for(int h=0;h<height;h++) {
    for(int w=0;w<width;w++) {
        int colour = 127;
      raster.setSample(w,h,0,colour); 
   }
}