Jim, Thanks for looking into this, and thanks to swpalmer for creating the test case.
I realize why the bars appear, and sadly, they appear on the LCDs I've tested as well. Rather than try and get you guys to introduce new features into your rendering engine (dithering in a 24-bit environment, for example) I was hoping some graphics gurus could tutor me on how to create grayscale gradients of limited range that don't have banding problems. It sounds like from your last paragraph that I should try a different set of colors above 50% luminance? Ben On Jun 20, 2006, at 11:48 PM, Jim Graham wrote:
When I run this case I can just make out 29 extremely faint bars on the screen which is exactly how many possible colors there are between the endpoints you chose so it looks like I am seeing adjacent colors on a true-color display. I'm a bit surprised that my eyes are that sensitive and that my LCD panels are that accurate (these are decent, but not top-of-the-line, monitors and often consumer LCD monitors don't really provide the full 256 shades of each color component so I guess I lucked out there). If you see it worse on other monitors (in particular, fewer than 29 bars across the window) then it may be that those aren't true 24-bit panels/displays. We currently only worry about dithering on 8-bit indexed destinations. We have a request outstanding for dithering on 15/16-bit displays, but we haven't gotten to it. This would be the first request for dithering on a TrueColor display. ;-) I agree that the problem is visible, but it is a lot less visible with colors and with other parts of the grayscale spectrum (you chose a band of 30 colors just below 50% luminance where it is most noticeable). It would be a fairly low priority for us to fix right now. Perhaps when we add support for >8bit per component image formats we might address issues like this. You might want to file a feature request on this so it doesn't get lost... ...jim [EMAIL PROTECTED] wrote:I was bored, so here's a test case... I can see the banding, just barely. I suppose some monitors will make it look worse than others. In any case I think the solution is dithering, but you will have to do it manually, simply supplying the rendering hint (g2.setRenderingHint (RenderingHints.KEY_DITHERING,RenderingHints.VALUE_DITHER_ENABLE); ) doesn't seem to have an effect on the behavior of GradientPaint. [code] /* * Gradient.java * * Created on June 5, 2006, 10:29 PM * */ package scott.palmer; import java.awt.Color; import java.awt.GradientPaint; import java.awt.Graphics; import java.awt.Graphics2D; import javax.swing.JFrame; import javax.swing.JPanel; /** * * @author Scott Palmer */ public class Gradient extends JPanel { public static void main(String [] args) { JFrame f = new JFrame("Gradient with Banding issues"); f.setContentPane(new Gradient()); f.setSize(800,200); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); f.setVisible(true); } protected void paintComponent(Graphics g) { Graphics2D g2 = (Graphics2D) g; g2.setPaint(new GradientPaint( 0,0,new Color(101,101,101), getWidth(),0,new Color (130,130,130))); g2.fillRect(0,0,getWidth(),getHeight()); } } [/code] [Message sent by forum member 'swpalmer' (swpalmer)] http://forums.java.net/jive/thread.jspa?messageID=119469 ===================================================================== ====== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff JAVA2D-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".====================================================================== ===== To unsubscribe, send email to [EMAIL PROTECTED] and include in the body of the message "signoff JAVA2D-INTEREST". For general help, send email to [EMAIL PROTECTED] and include in the body of the message "help".
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