[cups.general] Change PageSize option from Mac PDE?

Michael Sweet msweet at apple.com
Thu May 24 13:52:47 PDT 2012


Aaron,

On May 24, 2012, at 12:12 PM, Aaron Sher wrote:
> After thinking about this a bit more, I'm even more confused. You seem to be saying that the scaling factor is applied after the application does its rendering. That says to me that it has to be in one of the predefined filters like pdftoraster - is that right? If so, that isn't going to help us, because our filter (which is based on the Xenographics stuff) takes pdf as input and does its own rasterization very far down the line, partly in the printer firmware.

Third-party RIPs that are integrated this way can make their own choices; the cupsBorderlessScalingFactor stuff is a function of a CUPS Raster driver that uses the standard PostScript/PDF RIPs on the system and CUPS Raster file format.

> Second, what if the application is printing raster, like printing an image from Photoshop? The filter chain will get a PDF that wraps a raster image, and scaling that would introduce artifacts, wouldn't it?

Potentially, yes.

> It seems like this would only work reliably if the app is generating vector data, which is why I was looking for a way to increase the imageable area in the first place.

"Professional" applications can render outside the imageable area to provide document-specific overbleed data, but in general there is no way for a RIP to produce anything other than scaled or extended pixels at the edges.

> As an alternative, is it valid to pass negative numbers to ImageableArea, effectively defining negative margins? When I tried this, I got corrupted output, but I don't know whether it's the app (Preview) getting confused, or the filter.


None of the standard RIPs support imageable areas outside the paper dimensions, and the ImagingBBox field in the CUPS Raster page header uses unsigned integer values.

_________________________________________________________
Michael Sweet, Senior Printing System Engineer, PWG Chair





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