[cups.general] Printer wrong dpi

[Gernot Hassenpflug]

Jeremy <jeremycruz31 at gmail.com> writes:

>  Good day! I want help in solving this problem, my printer is canon
> ip1880 and works well in ubuntu 11.04, but the problem is it doesn't
> follow the dpi i have set it to, i always put it to 1200dpi(which is
> the maximum),and also set at high quality, and choose photo glossy
> paper, but the printer still print in low dpi, maybe at 300dpi
> only. But whenever i use the printer in Windows7, i'm not having
> problems with it, it gives the best result (1200dpi).

Hello,

This is not a CUPS problem but a driver problem.

What driver are you using? I assume it is the Canon driver for linux,
since gutenprint does not provide a driver for this printer.

I have a few comments:

1) Windows does not permit you to choose the resolution in the driver,
   only the "quality", so you have no way to know what the DPI value
   is.

2) Canon's printers have firmware which works with specific
   combinations of a) media type, b) quality selection, c) ink
   definitions, d) duplex setting, and e) resolution, which are sent
   as codes in the header of the printjob.
   Unfortunately, in CUPS all options are always present for
   selection.
   So depending on your combination of options, the firmware will
   either refuse to print at all, or will do something different to
   what you set.
   On a Windows system, you will not see conflicting options like
   this.

3) Most Canon printheads only have 300 DPI and 600 DPI available,
   while a minority (like apparently the iP1800 family) also has 1200
   DPI. In my experience, 1200 DPI is available only as part of the
   highest quality print setting for one of the photo media (depending
   on the model, it could be Photo Paper Glossy Plus, or something
   else). It is not a stand-alone selection.
   300 DPI is used only for the draft modes for plain media, 600 dPI
   for everything else.

>  Anyone know how to fix this? Also tried configuring it in the cups
> server but still the same.

No information about driver makes it hard to know what you have
available for changing, but it has nothing to do with CUPS.
-- 
Gernot Hassenpflug