Hello,
I have an image of a signature with height=50 and width=135 that I would
like to insert into a PDF. I would like to mask it with the signature
itself so that the white background of the image is gone and only the
signature remains. I've tried using the code below to do this, but I get
the following exception. Am I constructing the mask correctly? I assumed
that the number of bytes in the mask should be equal to the ceiling of the
number of pixels divided by 8(844 in this case). Is this correct?
java.lang.ArrayIndexOutOfBoundsException: 844
at com.lowagie.text.pdf.CCITTG4Encoder.nextState(Unknown Source)
at com.lowagie.text.pdf.CCITTG4Encoder.encodeT6(Unknown Source)
at com.lowagie.text.pdf.CCITTG4Encoder.compress(Unknown Source)
at com.lowagie.text.Image.getInstance(Unknown Source)
at com.lowagie.text.Image.getInstance(Unknown Source)
Here is the code:
<snip>
PlanarImage planarImage = getPlanarImage(value);
byte[] mask = createMask(planarImage);
Image maskImage =
Image.getInstance(
planarImage.getData().getWidth(),
planarImage.getData().getHeight(),
1,
1,
mask);
maskImage.makeMask();
maskImage.setInvertMask(true);
image.setAbsolutePosition(pageTokenDefinition.getX(),
pageTokenDefinition.getY());
image.setImageMask(maskImage);
pdfTemplate.addImage(image);
</snip>
private static byte[] createMask(PlanarImage image) {
double[][] pixels = imageToBandArray(image, 0);
int width = pixels[0].length;
int height = pixels.length;
byte[] mask = new byte[(int)Math.ceil(width * height / 8.0)];
int maskIndex = 0;
for (int pixelIndex = 0; pixelIndex < width * height; pixelIndex++) {
if (pixels[pixelIndex / width][pixelIndex % width] == 0) {
mask[(int)Math.floor(pixelIndex / 8.0)] |= (1 << (7 -
pixelIndex % 8));
}
}
return mask;
}
public static double[][] imageToBandArray(PlanarImage image, int band) {
Raster raster = image.getData();
int width = raster.getWidth();
int height = raster.getHeight();
int bands = raster.getNumBands();
double[][] bandArray = new double[height][width];
for (int n = 0; n < height; n++) {
raster.getSamples(0, n, width, 1, band, bandArray[n]);
}
return bandArray;
}
Thanks,
Chris
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