Can't invert an image

Hello,

I've been working on Java Advanced Imaging for a while to create FAX TIFF, but failed to invert the image's color (which was negative white-on-black) to positive.

BufferedImage form_img;

.....

RenderedOp rop;

ParameterBlock pb;

.....

pb =new ParameterBlock();

pb.addSource(form_img);

rop = JAI.create("invert",form_img);

.....

System.out.print("rop = " + rop +"\n\n");// DEBUG

System.out.print("pb = " + pb +"\n\n");// DEBUG

.....

img_enc.encode(rop);

The result:

rop = PlanarImage[minX=0 minY=0 width=0 height=0 tileGridXOffset=0 tileGridYOffs

et=0 tileWidth=0 tileHeight=0 sampleModel=null colorModel=null]

pb = java.awt.image.renderable.ParameterBlock@1b273cc

And sure enough, it gives out an exception when trying to encode image.

Anyone know where I did wrong?

Thanks

[1205 byte] By [QuaOsa] at [2007-11-15]