Fixed handling of empty JPEG-LS scans.

README

@@ -40,7 +40,7 @@ Standard JPEG compression, with 444 (aka "no") subsampling:
 
 $ jpeg -q <quality> infile.ppm outfile.jpg
 
-Standard JPEG compression, with 422 subsampling:
+Standard JPEG compression, with 420 subsampling:
 
 $ jpeg -q <quality> -s 1x1,2x2,2x2 infile.ppm outfile.jpg
 

codestream/sampleinterleavedlsscan.cpp

@@ -42,7 +42,7 @@
 ** A JPEG LS scan interleaving samples of several components,
 ** sample by sample.
 **
-** $Id: sampleinterleavedlsscan.cpp,v 1.15 2014/11/14 15:41:32 thor Exp $
+** $Id: sampleinterleavedlsscan.cpp,v 1.16 2022/06/08 10:54:55 thor Exp $
 **
 */
 
@@ -112,9 +112,12 @@ bool SampleInterleavedLSScan::ParseMCU(void)
   if (lines > 8) {
     lines = 8;
   }
+
+  if (lines == 0)
+    return false;
+
   if (m_pFrame->HeightOf() > 0)
     m_ulRemaining[0] -= lines;
-  assert(lines > 0);
   assert(m_ucCount < 4);
 
   //

codestream/singlecomponentlsscan.cpp

@@ -41,7 +41,7 @@
 /*
 ** A JPEG LS scan covering only a single component.
 **
-** $Id: singlecomponentlsscan.cpp,v 1.18 2014/11/14 15:41:32 thor Exp $
+** $Id: singlecomponentlsscan.cpp,v 1.19 2022/06/08 10:54:55 thor Exp $
 **
 */
 
@@ -96,8 +96,9 @@ bool SingleComponentLSScan::ParseMCU(void)
   }
   if (m_pFrame->HeightOf() > 0)
     m_ulRemaining[0] -= lines;
-
-  assert(lines > 0);
+
+  if (lines == 0)
+    return false;
 
   // Loop over lines and columns
   do {