Ok, we have a differing understanding of some of the image processing
involved in printing. While I still disagree, I agree to disagree and
will let the group decide the matter.
________________________________
From: Michael Sweet [mailto:msweet at apple.com]
Sent: Monday, April 18, 2011 1:38 PM
To: Petrie, Glen
Cc: ipp at pwg.org
Subject: Re: [IPP] More Discussion on bi-level, mono-chrome and color
On Apr 18, 2011, at 11:38 AM, Petrie, Glen wrote:
Can we change the required on mono to optional and bi-level be
required.
Bi-level required for any printer
Color required is color printer
Mono 1 toner - optional
Mono >2 toners - optional
And the other is the table are optional
Basically mono is a dithering of a single-color to produce an
output from saturation to white. But dithering is a fancy thresholding
(bi-level);
I don't agree with this. Thresholding is not dithering, which by
definition adds noise to the signal (in this case 2D color arrays) in
order to more accurately portray the signal given limited output
capabilities. The usage here is not to describe a particular algorithm
but rather to specify intent: high contrast black and white output.
You'd use this mode when scanning and printing forms, for example. (Oops
- time for another thread...) It is pretty clear I need to convert Table
2 to a list of paragraphs describing the keywords and their meanings in
detail.
The current requirements map to use cases - color and grayscale
(monochrome) printing are required for our current use cases. "Bi-level"
is not, although it is something we should consider for the scanned
forms use case. We can continue to debate the requirements, but every OS
and just about every driver for a color printer includes UI to print
color as grayscale... If the intent is to allow a limited mobile client
to do the same, we need to ask the printer to help out, and we can
decide whether that means 1-color or process (N-color, N>1) black.
________________________________________________________________________
Michael Sweet, Senior Printing System Engineer, PWG Chair
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