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1994.02.22 17:44 "CCITT RLE virker.", by Soren Pingel Dalsgaard
1994.02.23 12:58 "CCITT-RLE patch-to-make-it-work", by Soren Pingel Dalsgaard

1994.02.23 12:58 "CCITT-RLE patch-to-make-it-work", by Soren Pingel Dalsgaard

One person requested it so I though I'd post it to tiff@sgi.com instead.

The following changes will make it possible to write CCITT-RLE fax images using libtiff.

In tif_fax3.c changes have been made in functions Fax3Encode1DRow and Fax3Encode. Lines marked with a '+' in the first column have been added.

Also, in tif_ccitt.c the functions TIFFInitCCITTRLE and TIFFInitCCITTRLEW have been modified. The modification is actually a removal of the setting of Encoding-functions to point to a function producing an error message.

Sorry for not using diff, but I haven't got it right now...

---------------------------tif_fax3.c--------------------------------
In Fax3Encode1DRow():

     if (bs >= bits)
       break;
   }
+  if ((tif->tif_options & (FAX3_BYTEALIGN | FAX3_WORDALIGN)) && sp->b.bit < 8)
+    Fax3PutBits(tif, 0, sp->b.bit);
+  if ((tif->tif_options & FAX3_WORDALIGN) && ((long)tif->tif_rawcp & 1))
+    Fax3PutBits(tif, 0, 8);
   return (1);
 }

In Fax3Encode():

   Fax3EncodeState *sp = (Fax3EncodeState *)tif->tif_data;
   
   while ((long)cc > 0) {
+    if ((tif->tif_options & FAX3_NOEOL) == 0)
       Fax3PutEOL(tif);
     if (is2DEncoding(tif)) {
       if (sp->b.tag == G3_1D) {

---------------------------tif_ccitt.c--------------------------------

The functions are listed as they should be -- the difference should be obvious

int
TIFFInitCCITTRLE(TIFF* tif)
{
        TIFFInitCCITTFax3(tif);         /* reuse G3 compression */
        /*
         * This magic causes the regular G3 decompression
         * code to not skip to the EOL mark at the end of
         * a row, and to flush input data to a byte boundary
         * at the end of each row.
         */
        tif->tif_options |= FAX3_NOEOL|FAX3_BYTEALIGN;
        return (1);
}

int
TIFFInitCCITTRLEW(TIFF* tif)
{
        TIFFInitCCITTFax3(tif);         /* reuse G3 compression */
        /*
         * This magic causes the regular G3 decompression
         * code to not skip to the EOL mark at the end of
         * a row, and to flush input data to a byte boundary
         * at the end of each row.
         */
        tif->tif_options |= FAX3_NOEOL|FAX3_WORDALIGN;
        return (1);
}

---------------------------end-of-patch--------------------------------

--
Soren Pingel Dalsgaard
pingel@daimi.aau.dk
Department of Computer Science
Aarhus University
Ny Munkegade 116
DK-8000 Aarhus C
DENMARK