[Openicc] Thoughts IEEE PWG
msweet at apple.com
Mon May 9 11:19:41 PDT 2011
[Again, apologies for not replying to the original thread...]
Jan Peter Homann wrote:
> Hello to all,
> Reading "wd-ippjobprinterext3v10-20110330.pdf"
> seems to be quite strange to me.
> The ICC profiles used as example, are typical ICC-profile for exchange
> of documents.
Correct. The printer either provides vendor profiles resident on the printer or references to standard color profiles if those are all the printer supports. However, we also have an open issue on the current definition since (except for sRGB) the "standard" color space references are not available from a durable URL.
IMHO the really interesting use of printer-icc-profiles is for color proofing. I fully expect most clients to provide documents using standard color spaces or (in the case of PDF) using embedded color profiles. For client-managed color (printing targets and documents using local device color profiles) the client will provide documents with supported device color spaces.
> Also the rendering instructions in "5.2.2 print-rendering-intent" are
> not practical.
> If relative colorimteric is used as default for printing, there should
> always be blackpoint compensation be activated. Otherwise, it may will
> happen that details in dark tones are lost during printing.
Do you see a need for additional attributes to specify a white point or black point? Or is the summary confusing/inaccurate?
FWIW, I am happy to provide a normative reference to the ICC specification and to clear up the descriptions of each value for the rendering intent. My goal was to use ICC terminology for the values but also provide "lay person" descriptions since most of the PWG member representatives are not also their company's ICC representatives...
> By the way, reading the PWG documents, it seems unclear for me, which
> spool formats (PDF, TIFF, JPEG, CUPS Raster and which colorspaces are
See my other response for a summary.
> - Is it always the case, that the print spool format must be a raster
> format ?
No. However, for IPP Everywhere we are requiring that PWG Raster be supported by all printers for interoperability.
> - Or can the printing infrastructure inform the client, that also PDF
> could be used ?
Yes, the printer provides a list of supported MIME media types to the client ("document-format-supported") so that it may choose the best format to use for a particular job. The JPS3 spec also defines "preferred" values that a printer can supply to the client as a hint.
> - If PDF is supported, which flavours / elements of PDF would be supported ?
All of the required printing/static presentation elements from PDF 1.7/ISO 32000 would be supported.
> If there is one mailinglist to discuss color issues in IEEE PWG
> workflow, please let me know which one would be the one.
We don't have a list dedicated to color issues, but the "ipp at pwg.org" mailing list is the one that is discussing JPS3, PWG Raster, and IPP Everywhere. Instructions for subscribing are at the bottom of the IPP WG home page at:
Michael Sweet, Senior Printing System Engineer, PWG Chair
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