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
>
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