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Context fix for JBIG2 decoder

This commit is contained in:
Jakub Melka 2021-04-08 20:58:54 +02:00
parent 08f7b9480f
commit 39ed28706e
1 changed files with 66 additions and 5 deletions
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71
Pdf4QtLib/sources/pdfjbig2decoder.cpp
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@ -1706,7 +1706,7 @@ void PDFJBIG2Decoder::processSymbolDictionary(const PDFJBIG2SegmentHeader& heade
{
// Uncompressed data
collectiveBitmap = PDFJBIG2Bitmap(TOTWIDTH, HCHEIGHT, 0x00);
BMSIZE = HCHEIGHT * (TOTWIDTH + 7) / 8;
// BMSIZE is computed BMSIZE = HCHEIGHT * (TOTWIDTH + 7) / 8;
for (uint32_t y = 0; y < HCHEIGHT; ++y)
{
for (uint32_t x = 0; x < TOTWIDTH; ++x)
@ -2890,20 +2890,81 @@ PDFJBIG2Bitmap PDFJBIG2Decoder::readBitmap(PDFJBIG2BitmapDecodingParameters& par
switch (parameters.GBTEMPLATE)
{
case 0:
LTPContext = 0b1010010011011001; // 16-bit context, hexadecimal value is 0x9B25
{
// Figure 8. Reused context for coding the SLTP value
//
// ┌───┬───┬───┬───┬───┐
// │ 1 │ 0 │ 0 │ 1 │ 1 │
// ┌───┼───┼───┼───┼───┼───┼───┐
// │ 0 │ 1 │ 1 │ 0 │ 0 │ 1 │ 0 │
// ┌───┼───┼───┼───┼───┼───┴───┴───┘
// │ 0 │ 1 │ 0 │ 1 │ X │
// └───┴───┴───┴───┴───┘
//
// Bottom row from right to left: 1010
// Middle row from right to left: 0100110
// Top row from right to left: 11001
// => 0b1010 0100110 11001
LTPContext = 0b1010010011011001; // 16-bit context, hexadecimal value is 0xA4D9
break;
}
case 1:
LTPContext = 0b0011110010101; // 13-bit context, hexadecimal value is 0x0795
{
// Figure 9. Reused context for coding the SLTP value
//
// ┌───┬───┬───┬───┐
// │ 0 │ 0 │ 1 │ 1 │
// ┌───┼───┼───┼───┼───┼───┐
// │ 1 │ 1 │ 0 │ 0 │ 1 │ 0 │
// ┌───┼───┼───┼───┼───┴───┴───┘
// │ 1 │ 0 │ 1 │ x │
// └───┴───┴───┴───┘
//
// Bottom row from right to left: 101
// Middle row from right to left: 010011
// Top row from right to left: 1100
// => 0b101 010011 1100
LTPContext = 0b1010100111100; // 13-bit context, hexadecimal value is 0x153C
break;
}
case 2:
LTPContext = 0b0011100101; // 10-bit context, hexadecimal value is 0x00E5
{
// Figure 10. Reused context for coding the SLTP value
//
// ┌───┬───┬───┐
// │ 0 │ 0 │ 1 │
// ┌───┼───┼───┼───┼───┐
// │ 1 │ 1 │ 0 │ 0 │ 1 │
// ├───┼───┼───┼───┴───┘
// │ 0 │ 1 │ x │
// └───┴───┴───┘
//
// Bottom row from right to left: 10
// Middle row from right to left: 10011
// Top row from right to left: 100
// => 0b10 10011 100
LTPContext = 0b1010011100; // 10-bit context, hexadecimal value is 0x029C
break;
}
case 3:
LTPContext = 0b0110010101; // 10-bit context, hexadecimal value is 0x0195
{
// Figure 11. Reused context for coding the SLTP value
//
// ┌───┬───┬───┬───┬───┬───┐
// │ 0 │ 1 │ 1 │ 0 │ 0 │ 1 │
// ┌───┼───├───┼───┼───┼───┴───┘
// │ 0 │ 1 │ 0 │ 1 │ x │
// └───┴───└───┴───┴───┘
//
// Bottom row from right to left: 1010
// Top row from right to left: 100110
// => 0b1010100110
LTPContext = 0b1010100110; // 10-bit context, hexadecimal value is 0x02A6
break;
}
default:
Q_ASSERT(false);