Fix JBIG decoder.

Signed-off-by: yzrh <yzrh@noema.org>

1 files changed, 11 insertions, 0 deletions

diff --git a/src/jbig.c b/src/jbig.c
index 37afb50..c3c501b 100644
--- a/src/jbig.c
+++ b/src/jbig.c
@@ -209,6 +209,17 @@ _procline(int line, char *a, char *b, char *c)
 	/* The encoder must be erroneous */
 	uint16_t cx = 0;
 
+	if (line > 0) {
+		cx += (_ret[_width_padded * (_height - line)] & 0x20) << 2;
+		cx += _ret[_width_padded * (_height - line)] & 0x40;
+		cx += (_ret[_width_padded * (_height - line)] & 0x80) >> 2;
+	}
+
+	if (line > 1) {
+		cx += (_ret[_width_padded * (_height - line + 1)] & 0x40) >> 4;
+		cx += (_ret[_width_padded * (_height - line + 1)] & 0x80) >> 6;
+	}
+
 	for (int i = 0; i < _width; i++) {
 		_decode(cx);