A class which implements smooth downscaling for sources acquired line-by-line. Source scanlines are pushed into the algorithm one at a time in sequence from the top to the bottom of the source image. The destination is also populated in line-by-line fashion as soon as enough source lines are available to calculate a given line. The class is used as follows:

SmoothMinifier downscaler = new SmoothMinifier(sourceWidth, sourceHeight, numBands,
                                       destWidth, destHeight);
for(int i = 0; i < sourceHeight; i++) {
    byte[] b = source.getLine(i);
    if (shrinker.putSourceScanline(b, 0)) {
        break;
    }
}
NIOBuffer destBuf = downscaler.getDestination();

The algorithm used calculates the destination sample in each band by averaging over a box centered on the backward mapped location of the destination pixel. The box has dimensions ceil(sourceWidth/destWidth) x ceil(sourceHeight/destHeight).