[JAVA2D] Dithering
Hi,
In a certain piece of code we were using
Jai to dither a rendering of our chart objects, however this caused some
performance issues and we noticed the RenderingHints.KEY_DITHERING
so we tried moving the dithering
into the rendering of the chart that was already using the graphics2D of
a bufferedImage. While very performant, it doesn't yield the expected result.
Instead of dithered it gives us a thresholded black and white image. I
found very little information about the dithering hint while googling and
searching the forums, except people asking how to turn it off ;-)
Now my question is, should the pseudo
code below work ?
--- code snippet ---
byte[] map = {(byte)0xFF, (byte)0x00};
final BufferedImage buf = new BufferedImage(Math.round(fWidth*scale),
Math.round(fHeight*scale), BufferedImage.TYPE_BYTE_BINARY, new IndexColorModel(1,2,map,map,map));
final Graphics2D g2 = (Graphics2D)buf.getGraphics();
g2.setRenderingHint(RenderingHints.KEY_DITHERING,RenderingHints.VALUE_DITHER_ENABLE);
g2.scale(scale,scale);
fChart.setGraphics2D(g2);
fChart.render();
return buf;
--- code snippet ---
For reference we are using jdk 1.4.2_08
and any solution should work in java.awt.headless mode.
Any feedback is highly appreciated
Best regards,
Erik
-
Erik Vanherck - Product Delivery Manager
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Re: [JAVA2D] Dithering
Hi Eric,
final BufferedImage buf = new BufferedImage(Math.round(fWidth*scale),
Math.round(fHeight*scale), BufferedImage.TYPE_BYTE_BINARY, new
Well, here's you problem. You're creating a binary image, with
only two possible colors. So the dithering can't be smooth by
definition - each color can only be black or white.
Thanks,
Dmitri
On Thu, May 11, 2006 at 09:00:27AM +0200, Erik Vanherck wrote:
Hi,
In a certain piece of code we were using Jai to dither a rendering of our
chart objects, however this caused some performance issues and we noticed
the RenderingHints.KEY_DITHERING so we tried moving the dithering into the
rendering of the chart that was already using the graphics2D of a
bufferedImage. While very performant, it doesn't yield the expected
result. Instead of dithered it gives us a thresholded black and white
image. I found very little information about the dithering hint while
googling and searching the forums, except people asking how to turn it off
;-)
Now my question is, should the pseudo code below work ?
--- code snippet ---
byte[] map = {(byte)0xFF, (byte)0x00};
final BufferedImage buf = new BufferedImage(Math.round(fWidth*scale),
Math.round(fHeight*scale), BufferedImage.TYPE_BYTE_BINARY, new
IndexColorModel(1,2,map,map,map));
final Graphics2D g2 = (Graphics2D)buf.getGraphics();
g2.setRenderingHint(RenderingHints.KEY_DITHERING,RenderingHints.VALUE_DITHER_ENABLE);
g2.scale(scale,scale);
fChart.setGraphics2D(g2);
fChart.render();
return buf;
--- code snippet ---
For reference we are using jdk 1.4.2_08 and any solution should work in
java.awt.headless mode.
Any feedback is highly appreciated
Best regards,
Erik
Erik Vanherck - Product Delivery Manager
Inventive Designers
Visit http://www.inventivedesigners.com
Visit http://www.inventivedesigners.com/scriptura for Scriptura
information !
Phone: +32 - 3 - 8210170
Fax: +32 - 3 - 8210171
Email: [EMAIL PROTECTED]
Computers in the future may weigh no more than 1.5 tons. - Popular
Mechanics, forecasting the relentless march of science, 1949
Inventive Designers' Email Disclaimer:
http://www.inventivedesigners.com/email-disclaimer
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Re: [JAVA2D] Dithering
Hi Erik,
There are likely 2 different issues that you are dealing with here.
First is the issue of dithering during drawing vs. during imaging. We
currently do dithering when rendering an image into a lower color
resolution destination, but we don't do any dithering at all when we do
draw and fill types of rendering.
So, if you are using draw/fillGeometry(...) types of calls then you
would be seeing thresholding of the solid color. This is something that
we always meant to go back and fix, but there isn't much call for high
quality rendering to low color resolution destinations in today's world
of high memory and deep color displays. To force some dithering you
could use a workaround to force the geometry calls to use imaging
operations. One workaround would be to render to a higher color
destination and then copy the high color image into the B/W destination
using a drawImage(). That should force dithering. Another workaround
would be to use a custom Paint which simply returns a raster containing
a solid color. We currently implement Paint rendering as a series of
imaging operations so that would invoke our dithering as well. You
could use your own custom Paint or you could use a GradientPaint with
both colors the same for example. A color with an alpha value of less
than 1.0 (.f for float constructors or 254 for int constructors)
might also trigger a slower dithering algorithm.
On the other hand, even if you do use one of those workarounds, I'm
afraid our dithering implementation is optimized more for a decent
performance and acceptable quality compromise on 8-bit destinations than
it is for lower color destinations. There isn't much call for rendering
to lower color destinations these days given the wide prevalence of full
color screens and imagery so this has been a low priority.
The low priority of this type of rendering is perhaps reflected by the
fact that I couldn't find any open bugs against this problem, though I
know that anyone who would try to render into a monochrome image would
run into this. Please submit a bug with some example code so that we
can track the issue and provide a place for others to vote if they are
affected by this problem as well...
...jim
Erik Vanherck wrote:
Hi,
In a certain piece of code we were using Jai to dither a rendering of our
chart objects, however this caused some performance issues and we noticed
the RenderingHints.KEY_DITHERING so we tried moving the dithering into the
rendering of the chart that was already using the graphics2D of a
bufferedImage. While very performant, it doesn't yield the expected
result. Instead of dithered it gives us a thresholded black and white
image. I found very little information about the dithering hint while
googling and searching the forums, except people asking how to turn it off
;-)
Now my question is, should the pseudo code below work ?
--- code snippet ---
byte[] map = {(byte)0xFF, (byte)0x00};
final BufferedImage buf = new BufferedImage(Math.round(fWidth*scale),
Math.round(fHeight*scale), BufferedImage.TYPE_BYTE_BINARY, new
IndexColorModel(1,2,map,map,map));
final Graphics2D g2 = (Graphics2D)buf.getGraphics();
g2.setRenderingHint(RenderingHints.KEY_DITHERING,RenderingHints.VALUE_DITHER_ENABLE);
g2.scale(scale,scale);
fChart.setGraphics2D(g2);
fChart.render();
return buf;
--- code snippet ---
For reference we are using jdk 1.4.2_08 and any solution should work in
java.awt.headless mode.
Any feedback is highly appreciated
Best regards,
Erik
-
Erik Vanherck - Product Delivery Manager
Inventive Designers
Visit http://www.inventivedesigners.com
Visit http://www.inventivedesigners.com/scriptura for Scriptura
information !
Phone: +32 - 3 - 8210170
Fax: +32 - 3 - 8210171
Email: [EMAIL PROTECTED]
Computers in the future may weigh no more than 1.5 tons. - Popular
Mechanics, forecasting the relentless march of science, 1949
--
Inventive Designers' Email Disclaimer:
http://www.inventivedesigners.com/email-disclaimer
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Re: [JAVA2D] Dithering to black-and-white (monochrome) image
Hi Samo, On Thu, Nov 29, 2001 at 11:03:0p +0100, Samo Pitamic wrote: Hi all! I have the following problem: I have a Buffered image, then I want to transcode it into as small as possible format for wireless transfer. The most suitable format is PNG and since the wireless devices usually only support monochrome images, I want to encode the image in this mode. Therefore I create an IndexColorModel with two palette entries, black and white. Then I call a colorConvertOp.filter(srcImg,destImg), where destImage has the aforementioned monochrome IndexColorModel. While this works procedure, it is still missing a piece. The problem is the destImg looks quite bad, the light parts of the image are totally white, while others are totally black. What I want is a dithered BW image that would show some grayness. You'd need to use a color model with more than just two colors. There are predefined image formats in BufferedImage class which may suit you: TYPE_BYTE_GRAY- 256 gray values TYPE_BYTE_BINARY - 1, 2 or 4 bit Here is an example on how to use one of the default BufferedImage formats: (suppose srcImg is your source BufferedImage) BufferedImage dstImg = new BufferedImage(srcImg.getWidth(), srcImg.getHeight(), BufferedImage.TYPE_BYTE_GRAY); Graphics g = dstImg.getGraphics(); g.drawImage(srcImg, 0, 0, null); Thank you, Dmitri The question is: how do I dither an image? Specifically, how do I dither the image to two colors? I'm not familiar with the dithering algorithm, so I was wondering if there is some BufferedImageOp or RasterOp that can be configured to pose as dithering operation? Can dithering be expressed as a convolution or is it a totally another kind of operation? If yes, can someone point me to an appropriate kernel, if not, does someone have this operation implemented? I need a Java algorithm, preferebly something that works hand-in-hand with BufferedImage concepts. Thanks in advance, Samo === 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.
[JAVA2D] Dithering to black-and-white (monochrome) image
Hi all! I have the following problem: I have a Buffered image, then I want to transcode it into as small as possible format for wireless transfer. The most suitable format is PNG and since the wireless devices usually only support monochrome images, I want to encode the image in this mode. Therefore I create an IndexColorModel with two palette entries, black and white. Then I call a colorConvertOp.filter(srcImg,destImg), where destImage has the aforementioned monochrome IndexColorModel. While this works procedure, it is still missing a piece. The problem is the destImg looks quite bad, the light parts of the image are totally white, while others are totally black. What I want is a dithered BW image that would show some "grayness". The question is: how do I dither an image? Specifically, how do I dither the image to two colors? I'm not familiar with the dithering algorithm, so I was wondering if there is some BufferedImageOp or RasterOp that can be configured to pose as dithering operation? Can dithering be expressed as a convolution or is it a totally another kind of operation? If yes, can someone point me to an appropriate kernel, if not, does someone have this operation implemented? I need a Java algorithm, preferebly something that works hand-in-hand with BufferedImage concepts. Thanks in advance, Samo === 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".
Re: [JAVA2D] Dithering to black-and-white (monochrome) image
Samo, While this does not directly reply to your question please note that 8-to-1 bit dithering is possible using Java Advanced Imaging. Sample code for dithering using the ErrorDiffusion and OrderedDither operations is provided at http://swjscmail1.java.sun.com/cgi-bin/wa?A2=ind0110L=jai-interestP=R28205 Note that in the example a BufferedImage could be used as the source image of either operation. Brian I have the following problem: I have a Buffered image, then I want to transcode it into as small as possible format for wireless transfer. The most suitable format is PNG and since the wireless devices usually only support monochrome images, I want to encode the image in this mode. Therefore I create an IndexColorModel with two palette entries, black and white. Then I call a colorConvertOp.filter(srcImg,destImg), where destImage has the aforementioned monochrome IndexColorModel. While this works procedure, it is still missing a piece. The problem is the destImg looks quite bad, the light parts of the image are totally white, while others are totally black. What I want is a dithered BW image that would show some grayness. The question is: how do I dither an image? Specifically, how do I dither the image to two colors? I'm not familiar with the dithering algorithm, so I was wondering if there is some BufferedImageOp or RasterOp that can be configured to pose as dithering operation? Can dithering be expressed as a convolution or is it a totally another kind of operation? If yes, can someone point me to an appropriate kernel, if not, does someone have this operation implemented? I need a Java algorithm, preferebly something that works hand-in-hand with BufferedImage concepts. === 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.
