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JBIG2 decoder bugfixing

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This commit is contained in:
Jakub Melka 2021-07-08 11:34:52 +02:00
parent bdaaa01476
commit 01f97028ed
1 changed files with 12 additions and 4 deletions
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16
Pdf4QtLib/sources/pdfjbig2decoder.cpp
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@ -2905,7 +2905,9 @@ PDFJBIG2Bitmap PDFJBIG2Decoder::readBitmap(PDFJBIG2BitmapDecodingParameters& par
// Middle row from right to left: 0100110 // Middle row from right to left: 0100110
// Top row from right to left: 11001 // Top row from right to left: 11001
// => 0b1010 0100110 11001 // => 0b1010 0100110 11001
LTPContext = 0b1010010011011001; // 16-bit context, hexadecimal value is 0xA4D9 // WRONG! because first bits are lowest, we must flip the context (reverse it by bits)
//LTPContext = 0b1010010011011001; // 16-bit context, hexadecimal value is 0xA4D9
LTPContext = 0b1001101100100101; // 16-bit context, hexadecimal value is 0x9B25
break; break;
} }
@ -2925,7 +2927,9 @@ PDFJBIG2Bitmap PDFJBIG2Decoder::readBitmap(PDFJBIG2BitmapDecodingParameters& par
// Middle row from right to left: 010011 // Middle row from right to left: 010011
// Top row from right to left: 1100 // Top row from right to left: 1100
// => 0b101 010011 1100 // => 0b101 010011 1100
LTPContext = 0b1010100111100; // 13-bit context, hexadecimal value is 0x153C // WRONG! because first bits are lowest, we must flip the context (reverse it by bits)
//LTPContext = 0b1010100111100; // 13-bit context, hexadecimal value is 0x153C
LTPContext = 0b0011110010101; // 13-bit context, hexadecimal value is 0x0795
break; break;
} }
@ -2945,7 +2949,9 @@ PDFJBIG2Bitmap PDFJBIG2Decoder::readBitmap(PDFJBIG2BitmapDecodingParameters& par
// Middle row from right to left: 10011 // Middle row from right to left: 10011
// Top row from right to left: 100 // Top row from right to left: 100
// => 0b10 10011 100 // => 0b10 10011 100
LTPContext = 0b1010011100; // 10-bit context, hexadecimal value is 0x029C // WRONG! because first bits are lowest, we must flip the context (reverse it by bits)
//LTPContext = 0b1010011100; // 10-bit context, hexadecimal value is 0x029C
LTPContext = 0b0011100101; // 10-bit context, hexadecimal value is 0x00E5
break; break;
} }
@ -2962,7 +2968,9 @@ PDFJBIG2Bitmap PDFJBIG2Decoder::readBitmap(PDFJBIG2BitmapDecodingParameters& par
// Bottom row from right to left: 1010 // Bottom row from right to left: 1010
// Top row from right to left: 100110 // Top row from right to left: 100110
// => 0b1010100110 // => 0b1010100110
LTPContext = 0b1010100110; // 10-bit context, hexadecimal value is 0x02A6 // WRONG! because first bits are lowest, we must flip the context (reverse it by bits)
//LTPContext = 0b1010100110; // 10-bit context, hexadecimal value is 0x02A6
LTPContext = 0b0110010101; // 10-bit context, hexadecimal value is 0x0195
break; break;
} }