Closed aflueckiger closed 4 years ago
@aflueckiger This command worked. Can you check whether opj_compress can deal with it?
$ convert -compress lzw FedGazDe-1849-02-24-a-0001.tif -depth 8 -colorspace Gray /tmp/FedGazDe-1849-02-24-a-0001.tifs
$ tiffinfo /tmp/FedGazDe-1849-02-24-a-0001.tif
TIFF Directory at offset 0x16722 (91938)
Image Width: 1415 Image Length: 2374
Resolution: 300, 300 pixels/inch
Bits/Sample: 8
Compression Scheme: LZW
Photometric Interpretation: min-is-black
FillOrder: msb-to-lsb
Orientation: row 0 top, col 0 lhs
Samples/Pixel: 1
Rows/Strip: 2374
Planar Configuration: single image plane
Page Number: 0-1
Predictor: horizontal differencing 2 (0x2)
siclemat@asbru:/mnt/storage/harlie/projects/climpresso/federal-gazette/data_tif/FedGazDe/1849/02/24/a
@simon-clematide
Thanks, the command works as expected and the output tif can be converted further into jpeg 2000. We can do the conversion as follows:
convert -compress lzw FedGazDe-1851-01-04-a-0002.tif -depth 8 -colorspace Gray FedGazDe-1851-01-04-a-0002_conv.tif
opj_compress -r 10 -i FedGazDe-1851-01-04-a-0002_conv.tif -o FedGazDe-1851-01-04-a-0002_conv.jp2
The only remaining question is then what compression ratio we apply (using ratio 10, jp2 is around 320kb).
@simon-clematide As suggested here, I attempted to convert the extracted tif files of Feuille Federale into tif files with grey-scale, 8bit by
convert data_tif/FedGazDe/1998/02/03/a/FedGazDe-1998-02-03-a-0001.tif -depth 8 -colorspace Gray tiff_test/conv_FedGazDe-1998-02-03-a-0001.tif
Unfortunately, the conversion doesn't produce the expected output. The corresponding meta-information keeps the same concerning the relevant dimensions (bit, scheme).
Using opj_compress directly on the original TIFs is not an option since they are B/W instead of RGB or GREY. As quick sample suggests, the specs of the TIFs are fairly homogeneous prior to the change in 1999 (afterwards non-OCR). Only the dpi changes between 200 and 300.
Does anyone have a suggestion?