[IPP] Question on PWG draft specification mismatch & parsing

[IPP] Question on PWG draft specification mismatch & parsing

Michael Sweet msweet at apple.com
Wed May 4 20:17:10 UTC 2011

It should be 8-bits per pixel. I'm working on regenerating the files...

On May 4, 2011, at 12:57 PM, Petrie, Glen wrote:

> I was looking some of the PWGR images you provided.  I expected the sgray-8 to have 8 bits/color and 8 bits/pixel but the file shows 24 bits/pixel.  Which is correct?
> Glen
> From: ipp-bounces at pwg.org [mailto:ipp-bounces at pwg.org] On Behalf Of Roy Samuel
> Sent: Thursday, April 28, 2011 9:47 PM
> To: ipp at pwg.org; Michael Sweet
> Subject: [IPP] Question on PWG draft specification mismatch & parsing
> Hi Michael,
> I had downloaded the sample PWGRaster files from:http://ftp.easysw.com/pub/cups/examples/PWGRasterSamples.zip, with your latest working draft of the PWG raster found at: ftp://ftp.pwg.org/pub/pwg/ipp/wd/wd-ippraster10-20110327-rev.pdf. I compared the raster files in the folders:
> PWGRasterSamples\srgb-16  &
> PWGRasterSamples\srgb-8, with the specs given in the draft document.
> I found that neither of the directories contained files that adhered to the draft document w.r.t parsing the header. Specifically for the value of ‘NumColors’.
> --1--
> According to the draft document, bytes 420-423 need to contain ‘NumColors’ value, however, I found them to be zero. Are the sample files outdated??
> --2--
> Based on the decode algorithm given in the draft document, I had tried to obtain plain RGB raster data from a pwg-raster file. I had converted the PDF document obtained here:http://orenyomtov.com/downloads/testpage.pdf to obtain pwg-raster file using Google cloud print. I am able to get the pwg-raster file from GCP successfully. However, on converting the pwg-raster file to RGB data,  I have been successful in decoding around 1/6th or so, to raster data successfully, i.e. the top part of the page is being rendered successfully, while the rest is not rendered.
> (I use GIMP to open the output raster file in RAW mode).
> I have attached a screenshot of the output file that I’m able to view through GIMP (scaled down version).
> Is my algorithm wrong? Or are the specs incorrect?
> Regards.
> _________________________________________________
> Roy Samuel | Celstream Technologies | www.celstream.com
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Michael Sweet, Senior Printing System Engineer, PWG Chair

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