Java Buffered Image RescaleOp Transparency Issue

问题

I seem to be having an issue where I create a BufferedImage which has transparent pixels like this:

BufferedImage buff = new BufferedImage(i.getWidth(null), i.getHeight(null), BufferedImage.TYPE_INT_ARGB);

and it works fine until I filter it through the RescaleOp to darken it. When I do this, the image disappears. Here is my complete code just so you can see how I am setting this up:

    BufferedImage buff = new BufferedImage(i.getWidth(null), i.getHeight(null), BufferedImage.TYPE_INT_ARGB);
    Graphics2D g = buff.createGraphics();
    g.drawImage(i, 0, 0, null);
    g.dispose();
    RescaleOp filter = new RescaleOp(lightlevel, 0f, null);
    buff = filter.filter(buff, null);

My question is, how do I fix this so the buffered image will have its pixels darkened without affecting the transparency?

回答1:

You could try the RescaleOp that handles alpha, illustrated here, and use the same lightLevel for all color components.

来源：https://stackoverflow.com/questions/9612677/java-buffered-image-rescaleop-transparency-issue