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images [2016/03/02 15:19]
christian [Implementation] 		images [2016/09/24 08:15] (current)
dokuadmin ↷ Links adapted because of a move operation
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 ====== Images ====== ====== Images ======
  
-Bitmapped images are described in chapter 8.9 //Images// on page 203 of the {{pdf32000_2008.pdf#page=211|PDF specification}} on quite readable 14 pages.+Bitmapped images are described in chapter 8.9 //Images// on page 203 of the {{pdf:pdf32000_2008.pdf_page_211|PDF specification}} on quite readable 14 pages.
  
 The implementation is in package ''PDF Images''. The implementation is in package ''PDF Images''.
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 </code> </code>
  
-{{demo20_ImagesUsage.pdf}} shows the result with an example image.+{{pdf:demo20_imagesusage.pdf}} shows the result with an example image.
  
-{{demo21_Images.pdf}} shows some PDF features of images (masking, rotation, interpolation, inverting and alpha blended images).+{{pdf:demo21_images.pdf}} shows some PDF features of images (masking, rotation, interpolation, inverting and alpha blended images).
  
 ===== Object Models ===== ===== Object Models =====
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 </code> </code>
  
-In PDF images are defined by the number of bits per color component (1, 2, 4, 8 or 16 bit). The colorspace defines the number of components and their layout for a pixel. Any colorspace permitted in PDF can be used (see [[Colors]]). For images converted from Smalltalk, only ''/DeviceRGB'' (3 components), ''/DeviceGray'' (1 component) and ''/Indexed'' (1 component) are relevant. The ''/Indexed'' colorspace in PDF can only hold up to 255 colors.+In PDF images are defined by the number of bits per color component (1, 2, 4, 8 or 16 bit). The colorspace defines the number of components and their layout for a pixel. Any colorspace permitted in PDF can be used (see [[:colors]]). For images converted from Smalltalk, only ''/DeviceRGB'' (3 components), ''/DeviceGray'' (1 component) and ''/Indexed'' (1 component) are relevant. The ''/Indexed'' colorspace in PDF can only hold up to 255 colors.
  
 A ''PDF.ImageXObject'' is a stream whose contents is a byte string with the pixel bits. A row ends at the byte boundary. A row with one pixel with 3 components of 1 bits (= 3 bits), uses 1 byte (8 bit) for the row. As any stream, ImageXObjects can be compressed using filters. By default, ''/FlateDecode'' (zip) is used. A ''PDF.ImageXObject'' is a stream whose contents is a byte string with the pixel bits. A row ends at the byte boundary. A row with one pixel with 3 components of 1 bits (= 3 bits), uses 1 byte (8 bit) for the row. As any stream, ImageXObjects can be compressed using filters. By default, ''/FlateDecode'' (zip) is used.
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 ==== Filter ==== ==== Filter ====
  
-Although all Smalltalk images can be used for PDF, not all PDF images can be transformed to Smalltalk images. For one, several {{pdf32000_2008.pdf#page=22|filters}} specific to images are not implemented:+Although all Smalltalk images can be used for PDF, not all PDF images can be transformed to Smalltalk images. For one, several {{pdf:pdf32000_2008.pdf_page_22|filters}} specific to images are not implemented:
   * **RunLengthDecode** 8 bit monochrome images   * **RunLengthDecode** 8 bit monochrome images
   * **CCITTFaxDecode** CCITT encoded 1 bit monochrome images   * **CCITTFaxDecode** CCITT encoded 1 bit monochrome images
  • images.1456928361.txt.gz
  • Last modified: 2016/03/02 15:19
  • by christian