Glad I could help. But I saw that you've introduced some tab characters
into the sources. I guess it would be great if you would change the IDE
settings for the PDFBox project. Also, I'm not sure if the following
always works. Not all ICC color profiles have 4 components.
Seen in PDICCBased.java:
- int[] nbBits = { bpc, bpc, bpc };
+ int[] nbBits = { bpc, bpc, bpc, bpc }; //added 4th bpc to handle CMYK
On 29.04.2009 21:22:50 Daniel Wilson wrote:
> Jeremias, you got me very close. That part of the work is now committed.
> Thanks for the help!
>
> Daniel
>
> On Wed, Apr 29, 2009 at 7:46 AM, Daniel Wilson <
> [email protected]> wrote:
>
> > Thanks, Jeremias!
> >
> > That makes sense. I'll try implementing it & may have a couple more
> > questions.
> >
> > Daniel Wilson
> >
> >
> > On Wed, Apr 29, 2009 at 3:01 AM, Jeremias Maerki
> > <[email protected]>wrote:
> >
> >> As noted in another thread, bitmaps with 1bpp (or generally speaking:
> >> bitmaps with less than 8 bits per pixels) should be represented in
> >> memory using the IndexColorModel, i.e. a color lookup table. That way
> >> the pixels don't have to be extended to their full color values. The
> >> problem with the CMYK color space is that java.awt.image.IndexColorModel
> >> only supports sRGB. So you may end up with implementing a new ColorModel
> >> subclass which can represent non-sRGB colors. Of course, you could also
> >> map the CMYK colors to sRGB and still use IndexColorModel but if someone
> >> came an wanted a CMYK TIFF representation of a PDF, you'd have two color
> >> conversions involved which could have all sorts of side-effects. But
> >> that is certainly advanced stuff that could probably be handled at some
> >> later point.
> >>
> >> Here's an example of an IndexColorModel for an RGB-based 1bpp image:
> >> byte[] map = new byte[] {(byte)0x00, (byte)0xff};
> >> ColorModel cm = new IndexColorModel(1, 2, map, map, map);
> >>
> >> That's just the color model with the lookup table. The other key element
> >> is the DataBuffer instance (on which the Raster instance will operate)
> >> with
> >> the correct SampleModel. For 1bpp, this should in the end be a
> >> java.awt.image.MultiPixelPackedSampleModel, for example:
> >>
> >> MultiPixelPackedSampleModel packedSampleModel = new
> >> MultiPixelPackedSampleModel(
> >> DataBuffer.TYPE_BYTE, img.getWidth(), img.getHeight(), 1);
> >>
> >> AFAICT, the approach with creating a ColorModel instance in the
> >> PDColorSpace subclass is probably wrong if you want to get an optimized
> >> in-memory representation, since the color model just interprets the
> >> colors. It doesn't know how the pixels are represented (SampleModel).
> >> Only the XObject itself knows how many bits represent a pixel.
> >>
> >> HTH
> >>
> >> On 29.04.2009 03:16:37 Daniel Wilson wrote:
> >> > Given a bpc = 1 and a DeviceCMYK color space:
> >> >
> >> > byte[] array = getPDStream().getByteArray();
> >> >
> >> > creates an array with width*height / 8 bytes.
> >> >
> >> > PDColorSpace colorspace = getColorSpace();
> >> > ColorModel cm = colorspace.createColorModel( bpc );
> >> > WritableRaster raster = cm.createCompatibleWritableRaster( width, height
> >> );
> >> > DataBufferByte buffer = (DataBufferByte)raster.getDataBuffer();
> >> > byte[] bufferData = buffer.getData();
> >> >
> >> > cm is a ColorModel reporting 32 pixelBits.
> >> > bufferData now has width*height * 4 bytes -- or 32 times as many as
> >> array.
> >> >
> >> >
> >> > System.arraycopy( array, 0,bufferData, 0,
> >> > (array.length<bufferData.length?array.length: bufferData.length) );
> >> > The ternary in there saves us from a buffer overflow ... but that's
> >> still
> >> > the wrong answer.
> >> > Just copying a 1-bit/pixel buffer into a 32-bit/pixel buffer cannot be
> >> the
> >> > right answer.
> >> >
> >> > Am I to read each BIT of the source array and convert it to a 32-bit
> >> integer
> >> > to write? So 0 becomes 0x00000000 and 1 becomes 0xFFFFFFFF ?
> >> >
> >> > Or is colorspace.CreateColorModel creating the wrong one? This looks
> >> right
> >> > ...
> >> >
> >> > logger().info("testing Sector9's implementation");
> >> >
> >> > int[] nbBits = { bpc, bpc, bpc, bpc };
> >> > ComponentColorModel componentColorModel =
> >> > new ComponentColorModel( createColorSpace(),
> >> > nbBits,
> >> > false,
> >> > false,
> >> > Transparency.OPAQUE,
> >> > DataBuffer.TYPE_BYTE );
> >> >
> >> > Thanks for your ideas!
> >> >
> >> > Daniel Wilson
> >>
> >>
> >>
> >>
> >> Jeremias Maerki
> >>
> >>
> >
Jeremias Maerki
