Re: [csjava-developer] performance puzzle

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It sounds like it is the JDK 5, on my Linux box (using a 200MHz
processor and Java v1.4.2_08) it took about 7 seconds on a 1024x768
image.<br>
<br>
As an update on my main Windows computer, the shop didn't find anything
wrong with it. <span class="moz-smiley-s2"><span> :-( </span></span><br>
Must need to re-install Windows.<br>
<br>
This time, I'm going to install Windows <i>and</i> Linux on it
(Keeping my slow one, of course).<br>
<br>
Daryl.<br>
<br>
Toby Donaldson wrote:
<blockquote cite="mid...@sf..."
 type="cite">Hi,
  <br>
  <br>
Can anyone help me to figure out why the code below is so slow? It&nbsp;
converts and image to grayscale pixel by pixel, but when I've run it&nbsp;
(on two different computers --- Windows and Mac OS X), it takes 20 or&nbsp;
more seconds to process a medium sized image. I would have expected&nbsp; it
take less than a second or so.
  <br>
  <br>
The bit-twiddling code should be quite efficient, since such&nbsp;
operations are (hopefully) converted to single assembly-language&nbsp;
instructions.
  <br>
  <br>
I've been using JDK 5.0 (aka 1.5), so maybe that's causing the problem?
  <br>
  <br>
Toby
  <br>
--
  <br>
Dr. Toby Donaldson
  <br>
School of Computing Science
  <br>
Simon Fraser University (Surrey)
  <br>
  <br>
  <br>
  <br>
public static void dprint(String s) {
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; System.out.println(s + " " + (new Date()));
  <br>
&nbsp;&nbsp;&nbsp; }
  <br>
  <br>
&nbsp;&nbsp;&nbsp; public static void test4(String fname) {
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; try {
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; dprint("Creating buffered image:");
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; BufferedImage img = ImageIO.read(new File(fname));
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; dprint(".. done");
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; final int width = img.getWidth();
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; final int height = img.getHeight();
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; dprint("Starting grayscale conversion:");
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; for (int i = 0; i &lt; width; i++) {
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; for (int j = 0; j &lt; height; j++) {
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int rgb = img.getRGB(i, j);
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int b = (rgb &amp; 0x000000FF);
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int g = (rgb &amp; 0x0000FF00) &gt;&gt; 8;
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int r = (rgb &amp; 0x00FF0000) &gt;&gt; 16;
  <br>
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int lum = (int) ((r + g + b) / 3.0);
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int alpha = rgb &amp; 0xFF000000;
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int red = lum &lt;&lt; 16;
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int green = lum &lt;&lt; 8;
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int blue = lum;
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; int newARGB = alpha | red | green | blue;
  <br>
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; img.setRGB(i, j, newARGB);
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; dprint("... done");
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; } catch (IOException e) {
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; e.printStackTrace();
  <br>
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; }
  <br>
&nbsp;&nbsp;&nbsp; }
  <br>
  <br>
  <br>
  <br>
  <br>
  <br>
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