[IPP] (PWG) Raster Question on what is required

[IPP] (PWG) Raster Question on what is required

Michael Sweet msweet at apple.com
Thu Apr 28 20:46:50 UTC 2011


Oh, and since we are using the compressed version new raster lines begin where the last line ends. Hopefully the other examples I'll be adding will make that more clear...

On Apr 28, 2011, at 1:22 PM, Petrie, Glen wrote:

> Mike,
>  
> Question on your definition of bytes-per-line (BPL): You have it ending at an octet (8-bit) but I have seen cases where the boundary is at the word or 32-bit level.   In fact, I have seen were people clip a line by changing the number of pixel per line but not the bytes-per-line.   What has been your experience?   Suggestion: Leave the equation out of specification and it is understood or is stated that new raster lines begin at multiples of bpl.
>  
> Glen
>  
>  
> From: Michael Sweet [mailto:msweet at apple.com] 
> Sent: Thursday, April 28, 2011 10:27 AM
> To: Petrie, Glen
> Cc: ipp at pwg.org
> Subject: Re: [IPP] (PWG) Raster Question on what is required
>  
> On Apr 28, 2011, at 10:21 AM, Petrie, Glen wrote:
>> ...
>> libtiff (the most widely-used TIFF library) supports 16-bits per color.
>>  
>> I must be looking at the wrong version because TIFF 6.0 shows only <8,8,8> http://www.libtiff.org/support.html
>  
> Hmm, they must have removed 16-bit support at one point - back when I was doing print software for SGI workstations the "Sam Leffler" version of libtiff supported it...
> 
> 
> ... 
> I think for interoperability we want a minimum set for interoperability (and to address the use cases/design requirements). But most values of color space and bit depth should be optional.
>  
> Ok, then from your color-spaces, the required bits-per-color would 1 and 8.  Also, the required bits-per-pixel would be 1, 8, 24
>  
> Right.
>  
>> One more time.  Does conformance to pwg-raster-back-side mean “the printer will perform the indicated transforms” or this is an identifier stating what the “state” of the back-side image is?
>  
> Conformance for a printer means that it will advertise what it needs. For a client it means the client will transform the back side images as indicated by the printer.
>  
> ________________________________________________________________________
> Michael Sweet, Senior Printing System Engineer, PWG Chair
>  

__________________________________________________
Michael Sweet, Senior Printing System Engineer, PWG Chair


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