How to decrease jpeg size without losing quality?

Question

i am creating different size of images reading with bufferedimage then redrawing image with different sizes...
I have created a 500*375 -192 kb picture from original with my code then uploaded it to flickr....it produced 500*375 picture with 133 kb...and quality seems the same...please look my code below...maybe the colour table of my drawing or some property must change....where is the point?
thank you
response.reset();
          ServletOutputStream cikti=response.getOutputStream();
          BufferedImage servletResim=new BufferedImage(500,375,BufferedImage.TYPE_INT_RGB);
          Graphics2D graf=(Graphics2D) servletResim.getGraphics();
          graf.drawImage(image, 0, 0, 500, 375, null);
          JPEGImageEncoder enkoder=JPEGCodec.createJPEGEncoder(cikti);
          JPEGEncodeParam param = enkoder.getDefaultJPEGEncodeParam(servletResim);
          int quality =100;
          quality = Math.max(0, Math.min(quality, 100));
          param.setQuality((float)quality / 100.0f, false);
          enkoder.setJPEGEncodeParam(param);
          enkoder.encode(servletResim);
          cikti.close();

Answer 1

The quality may "seem" the same, but it probably isn't. With most photos you can reduce the JPEG to 85% quality without noticing much.