[Kde-print-devel] [Bug 77624] Wish: More advanced image printing capabilities

Dik Takken d.h.j.takken at phys.uu.nl
Sat Jan 13 13:42:47 CET 2007

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------- Additional Comments From d.h.j.takken phys uu nl  2007-01-13 13:42 -------
Kurt Pfeifle suggested in Bug #62739 that it might be a very good idea to allow applications to provide bitmaps to KDEPrint in stead of Postscript files.

So, some more thoughts about this that pop into my mind:

I did not know that CUPS can print images directly. It sounds like a great improvement over the current situation if applications can just hand over a PNG file to CUPS.

Two main reasons I see why this is a *very* good idea:

* Most applications do a very bad job generating proper Postscript files.
* Printing a 6 Megapixel image *should* be a breeze, but it seems that due to the conversion to Postscript format, the printing system needs to digest HUGE Postscript files that take very, very long to render, with Ghostscript consuming all system resources.

Another issue (related to print size) that seems to be a problem in current KDEPrint is that applications have no idea about the image resolution required by the printer. Even if the printer is set to its lowest DPI setting, the application does not know this and sends a ultra-high resolution image anyways. Sometimes, I even get the impression that applications do not even know the maximum DPI setting of the printer they are sending the job to. The result is that the image data generated by the application is overkill for one printer, while another printer receives too little data to print the sharpest possible image.

Please correct me if I am mistaken here!

If applications are allowed to always send the entire image in, say, PNG format (never a big performance problem I think, even for a 16 Megapixel image) then KDEPrint can do the required upscaling / downscaling. When scaling down, KDEPrint could offer the user a choice between linear/bicubic/... scaling. When scaling up KDEPrint could even offer options to add a layer of barely visible correlated monochromatic noise to the image, which helps a lot in making the final print appear more detailed.

These are things that will become possible (maybe in KDE 4.2 or so) when KDE 4  allows applications to provide a bitmap image file.

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