Dithering missing for Black/Red/White Labels

[EilersT]

My Setup

• Printer: QL-800
• Tape 62mm Black/Red on White DK-22251
• OS: Ubuntu 18.04.3 LTS
• Connection USB
• Testpattern TestRG.png 696x108 px

• Printer output

My Problem

i would like to print Pictures and Graphics with my QL-800. Unfortunately the printer produces only B&W Patterns and no gray- redscale printouts. Dithering has no effect. Could be related to Issue https://github.com/pklaus/brother_ql/issues/62

Any help would be much appreciated

Console

• Printing command: $ sudo brother_ql -m QL-800 -p usb://0x04f9:0x209b print -l 62red --red TestRG.png

• Printing command with dithering $ sudo brother_ql -m QL-800 -p usb://0x04f9:0x209b print -l 62red -d --red TestRG.png

• Console output

  $ sudo brother_ql -m QL-800 -p usb://0x04f9:0x209b print -l 62red -d --red TestRG.png 
  INFO:brother_ql.backends.helpers:Sending instructions to the printer. Total: 20332 bytes.
  Traceback (most recent call last):
  File "/usr/local/bin/brother_ql", line 11, in <module>
  load_entry_point('brother-ql==0.9.dev0', 'console_scripts', 'brother_ql')()
  File "/home/tilman/.local/lib/python2.7/site-packages/click/core.py", line 764, in __call__
  return self.main(*args, **kwargs)
  File "/home/tilman/.local/lib/python2.7/site-packages/click/core.py", line 717, in main
  rv = self.invoke(ctx)
  File "/home/tilman/.local/lib/python2.7/site-packages/click/core.py", line 1137, in invoke
  return _process_result(sub_ctx.command.invoke(sub_ctx))
  File "/home/tilman/.local/lib/python2.7/site-packages/click/core.py", line 956, in invoke
  return ctx.invoke(self.callback, **ctx.params)
  File "/home/tilman/.local/lib/python2.7/site-packages/click/core.py", line 555, in invoke
  return callback(*args, **kwargs)
  File "/home/tilman/.local/lib/python2.7/site-packages/click/decorators.py", line 17, in new_func
  return f(get_current_context(), *args, **kwargs)
  File "build/bdist.linux-x86_64/egg/brother_ql/cli.py", line 147, in print_cmd
  File "build/bdist.linux-x86_64/egg/brother_ql/backends/helpers.py", line 76, in send
  File "build/bdist.linux-x86_64/egg/brother_ql/reader.py", line 164, in interpret_response
  NameError: ("Printer response doesn't start with the usual header (80:20:42)", '61 72 72 61 79
  28 27 42 27 2C 20 5B 31 32 38 2C 20 33 32 2C 20 36 36 2C 20 35 32 2C 20 35 36 2C 20 34 
  38 2C 20 30 2C 20 30 2C 20 30 2C 20 30 2C 20 36 32 2C 20 31 30 2C 20 30 2C 20 30 2C 20 
  33 35 2C 20 30 2C 20 30 2C 20 30 2C 20 30 2C 20 30 2C 20 30 2C 20 30 2C 20 30 2C 20 30 
  2C 20 30 2C 20 31 32 39 2C 20 30 2C 20 30 2C 20 30 2C 20 30 2C 20 30 2C 20 30 5D 29')

[EilersT]

Figured it out myself. Ditherting is not implemented with Red and Black printing.

[pklaus]

Thanks for reporting this. Actually, it would be great if this works. I'll see, what I can do here. Do dithering before or after deciding/thresholding between black/red pixels? I have to try and see. For now, I'll reopen the issue.

[EilersT]

I worked on the "conversion.py" that is posted on my GitHub page. Dithering is working but i cant get the contrast right.