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 The Progressive Graphics File
 =============================
  
 For more information see http://www.libpgf.org. There you can find some
 documents concerning this progressive graphic file codec.
  
 This project is hosted on the Sourceforge.net platform. For support and
 questions, please use the installed mailing list and forums there. 
 The Sourceforge URL of our project is: http://sourceforge.net/projects/libpgf
  
 =============================
 Release Notes
 
 Version 7.21.7, (Thu, 18 Feb 2021)
 ------------------------------------
 
 1. The new version is a minor bug fix of versions 7.15.25 to 7.21.2.
 
 2. This bug fix for ROI decoding only. This bug fix is necessary if several 
    Read() and ResetStreamPos() operations are called with the same PGFimage
    object after a single Open() call.
 
 
 Version 7.21.2, (Sun, 17 Jan 2021)
 ------------------------------------
 
 1. The new version is a documentation and build tool update of version 7.19.3.
 
 
 Version 7.19.3, (Tue, 15 Jan 2019)
 ------------------------------------
 
 1. The new version is a minor update of version 7.15.25.
 
 2. This version fixes a compilation bug seen when ROI support is disabled.
 
 
 Version 7.15.32, (Thu, 6 Aug 2015)
 ------------------------------------
 
 1. The new version is a minor update of version 7.15.25.
 
 2. This version improves the reuse of CPGFImage objects for several decoding operations. 
    It clarifies the usage of CPGFImage::Close() and CPGFImage::Destroy() by deletion of 
    Close(). Several reading operations can be performed in the following way:
    Open(), Read(), GetBitmap(), ResetStreamPos(), Read(), GetBitmap(), ResetStreamPos(), ...
    Calling Destroy() frees all allocated ressources and reinitializes the object to the 
    same state as the constructor does. This allows the reuse of the CPGFImage object for 
    encoding and decoding: 
    SetHeader(), ImportBitmap(), Write(), ResetStreamPos(), Destroy(), Open(), Read(), GetBitmap() 
     
 3. Caching or skipping of user data (meta data) while opening a PGF image can be controlled
    by a new UserdataPolicy in ConfigureDecoder().
  
 
 Version 7.15.25, (Sat, 20 June 2015)
 ------------------------------------
 
 1. This new version is a replacement of version 6.14.12. 
    In case you use the ROI decoding, we strongly encourage using version 6.15.25 instead of an older version.
 
 2. This version fixes some decoder bugs only seen in ROI decoding.
    ROI decoding is now also supported for Bitmap and RGB12 image modes.
 
 3. This version introduces a new and more efficient data format for binary images (bitmaps). 
    The new format allows ROI decoding.
    The decoder supports both the old and the new format, but ROI decoding works only with the new format.
 
 4. The two reserverd bytes in PGFHeader are now used for a more detailled PGF version number.
 
 5. The Visual Studio project files are in the VS12 format.
 
  
 Version 6.14.12, (Wed, 9 April 2014)  
 ------------------------------------
  
 1. The new version is a minor update of version 6.12.24. 
 
 2. It mainly contains some fixes of memory leaks in the OpenMP part and some improvements suggested by cppcheck and Coverity.
 
 3. The Visual Studio project files are in the VS11 format.
 
 
 Version 6.12.24, (Thu, 14 June 2012) 
 ------------------------------------ 
  
 1. The new version is a replacement of version 6.11.42. 
    In case you use the ROI encoding scheme, we strongly encourage using version 6.12.24 instead of version 6.11.42.
  
 2. This version fixes some decoder bugs, sometimes seen in ROI decoding.
  
 3. This version allows a simpler user-data handling, especially for uncached metadata. The following two methods
    in the class PGFimage are designed for this purpose:
 
         GetUserDataPos() returns in an opened PGF image the stream position of the user data area.                                                              
 
         WriteImage() encodes and writes the image at the current stream position. This method is called after
         WriteHeader(). In case you want to write uncached metadata into the stream, then do that after WriteHeader() 
         and just before WriteImage(). If you are not interested in writing uncached metadata, then you usually use
         Write() instead of WriteImage(). WriteHeader() and WriteImage() are called inside of Write(). 
 
 
 Version 6.11.42, (Sun, 23 Oct 2011) 
 ----------------------------------- 
  
 1. The new version is a replacement of version 6.11.24. 
    We strongly encourage using version 6.11.42 instead of version 6.11.24.
  
 2. This version fixes some decoder bugs, only seen in lossless compression of 
    large images.
  
 3. The rarely used, but sometimes misused, background information (3 Bytes) 
    in the PGFHeader has been replaced by
 
      UINT8 usedBitsPerChannel;    // number of used bits per channel 
                                   // in 16- and 32-bit per channel modes
      UINT8 reserved1, reserved2;  // not used
 
 The value usedBitsPerChannel is helpful in case you have more than 8 (16) but 
 less than 16 (32) significant bits per channel, stored in the most 
 significant bits of a pixel. For example, you have a grayscale image with 14 
 bit significant data per pixel stored in the ImageModeGray16 pixel format. In 
 case you have left shifted the 14 bits to be the most significant 14 bits, 
 then you should set usedBitsPerChannel=14. This will increase the compression 
 ratio without any drawbacks, because the 14 bits are internally right shifted. 
 On the other side, if the 14 bits are the least significant bits in 
 your 16 bit pixel format, then you shouldn't set usedBitsPerChannel. It will 
 be automatically set to 16, but this is no problem, since the not used most 
 significant bits per pixel are never encoded at all. So, in both cases the same 
 compression ratio will result.