[PDFBOX-1445] /ImageMask true does not work. Patch included.

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Fix Version/s: 1.8.0
• Assignee: Andreas Lehmkühler
• Reporter: Dave Smith
• Created: 13/Nov/12 13:49
• Updated: 23/Mar/13 12:56
• Resolved: 18/Nov/12 14:20

Description

I have the following pdf...

10 0 obj
<<
/Type /Page
/MediaBox [ 0 0 612.0 792.0 ]
/Parent 3 0 R
/Resources << /XObject << /Obj4 4 0 R /Obj5 5 0 R /Obj6 6 0 R /Obj7 7 0 R >> /ProcSet [ /PDF /Text /ImageB /ImageC /ImageI ] >>
/Contents [ 8 0 R 9 0 R ]
>>
endobj

Which then draws 4 images. The first one is a "base" and then rest are image masks

9 0 obj
<< /Filter /FlateDecode /Length 121 >>
stream
q
612.00 0 0 792.00 0.00 0.00 cm
/Obj4 Do
Q
q
0.129 g
524.16 0 0 556.80 48.00 127.68 cm
/Obj5 Do
Q
q
0.302 g
220.80 0 0 398.40 48.00 286.08 cm
/Obj6 Do
Q
q
0.204 g
524.16 0 0 469.44 48.00 185.28 cm
/Obj7 Do
Q
endstream
endobj

4 0 obj
<< /Type /XObject /Subtype /Image /Width 1275 /Height 1650 /BitsPerComponent 8
/ColorSpace /DeviceGray /Filter [ /FlateDecode /DCTDecode ] /Length 50485 >>
stream
endstream
endobj

5 0 obj
<< /Type /XObject /Subtype /Image /Width 2184 /Height 2320 /BitsPerComponent 1
/ImageMask true /Filter /CCITTFaxDecode /DecodeParms << /K -1 /Columns 2184 >>
/Length 15580 >>
stream

etc ...

The current code simply treats the imagemask as an image. Since this is just a 1 bit image it has no Alpha channel it overwrites the existing image and we simply get the last image drawn.

In

org.apache.pdfbox.util.operator.pagedrawer.Invoke.java

method

public void process(PDFOperator operator, List<COSBase> arguments) throws IOException

after

if (awtImage == null)

{ LOG.warn("getRGBImage returned NULL"); return;//TODO PKOCH }

If you add the following code it fixes the problem. I can not provide the sample doc due to privacy reasons.

/**

• Spec 8.9.6.2
• If ImageMask is true then the image is one bit. Black means draw the current colour and white means use the colour on the current image (ie Mask).
• Convert the map to an image with an Alpha channel so we can lay it on top
  */
  if(image.getImageMask())
  {
  Color currentColour = drawer.getGraphicsState().getStrokingColor().getJavaColor();
  final int onColour = 0xff000000 | currentColour.getRGB();
  BufferedImage bia = new BufferedImage(awtImage.getWidth(),awtImage.getHeight(),BufferedImage.TYPE_INT_ARGB);
  for(int y=0;y<awtImage.getHeight();y++)
  Unknown macro: { for(int x=0;x<awtImage.getWidth();x++) { bia.setRGB(x, y, (awtImage.getRGB(x, y) & 0x00ffffff) == 0xffffff ? 0x00ffffff : onColour); } }

  awtImage = bia;
  }