Print resolution on my HP9180

[Ed Blagden]

Hi

I recently bought my first proper photo printer - a HP9180 - and I am very confused about DPI settings, and I hope I can get some help on this learned forum.

I am using LR2 and a Canon EOS5D, and at various times I have read / heard the following statements, all of which contradict each other:

- It is best to print at the native resolution of the image itself - usually around 250dpi for an A3 print from the 5D, depending on crop.
- It is best to print an upressed image - about 50% higher than native resolution of the image, say around 375dpi for the above example, because the LR2 output sharpening algorithm works best at this setting.  I seem to remember Schewe pronouncing on this in the LR2 video tutorial.
- It is best to upres or downres your image to print at the native resolution of the printer, or whole (or half) multiples thereof - the only problem is, I can't find what the native dpi for the HP9180 is in the documentation.  Does anyone here know the figure??

All of these bits of advice seem to contradict each other - which is right?

Also, in the print setup option which opens from LR but which is evidently the HP printer driver, do I use the "best" or "maximum dpi" setting?  Isn't the dpi set by the output file which the computer sends to the printer?

As you can tell, I am confused... any help would be appreciated.

Ed

[John.Murray]

Hi Ed!

In the first Lightroom Video series, Michael recounts a converstation with an HP engineer regarding that - essentially if the resolution is anywhere between 180-450 dpi - let the print driver itself sort it out.  I have always used "best" when printing to my 9180.

[DarkPenguin]

Some oddities are sorted out when I use Max DPI.  Some things (grasslands) tend to get a wee bit muddy when I do not use max dpi.

[Ed Blagden]

Thanks people,

My takeaway from this is not to worry about native printer resolution, and to just use an appropriately ressed file from LR2.  Also, I will try out Max DPI and see if I can see any difference.

This still does not answer the question of what resolution print file should be generated in LR2.  Is it best to go with whatever native resolution is being generated by the image (assuming this is more than 180dpi) or is it best to up-res the image (so for example a 250dpi native image becomes 370)?  Schewe mentioned the latter in the LR2 video, but with heavy caveats that this was still something they were evaluating.

Thanks!

Ed

[Ernst Dinkla]

Thanks people,

My takeaway from this is not to worry about native printer resolution, and to just use an appropriately ressed file from LR2.  Also, I will try out Max DPI and see if I can see any difference.

This still does not answer the question of what resolution print file should be generated in LR2.  Is it best to go with whatever native resolution is being generated by the image (assuming this is more than 180dpi) or is it best to up-res the image (so for example a 250dpi native image becomes 370)?  Schewe mentioned the latter in the LR2 video, but with heavy caveats that this was still something they were evaluating.

Thanks!

Ed

Not familiar with the B9180 driver but if you change from normal to best in the driver isn't there a small text showing the requested input resolution changing from 300 to 600 PPI (Z3100 does that) or from 600 to 1200 PPI?  That are the native resolutions of the printer for the different quality settings.

Not familiar with Lightroom either but as I understand it shouldn't it do an upsampling or downsampling to the selected native resolution on the fly with good algorithms like Qimage does it ?  So not transferring that task to the printer driver? So no reason to do it yourself nor a reason to worry whether the HP driver has the right algorithm for it.


met vriendelijke groeten, Ernst Dinkla

Try: http://groups.yahoo.com/group/Wide_Inkjet_Printers/

[NikoJorj]

The best would be to test it : take a good & sharp image, make a virtual copy and crop it extensively to an area of interest to be able to print patches of reasonable size even at lower resolutions. For each resolution (180, 150, 120, 90dpi) make one print resampled in the driver, another resampled in LR, and look.

I'm sorry not to be HP-specific, but here are my findings with my Epson R1800 and Lightroom :
- I don't see any quality issue before print resolution goes under 150-200dpi, so all the following only applies to resolutions under 150dpi,
- The Epson driver does a nearest-neighbour interpolation leading to discernable square pixels (ouch),
- Lightroom does a very decent job of uprezzing, I'd think it's something like bicubic (perhaps with some mild sharpening?).
Keep in mind that uprezzing is creating information from (almost) nothing, so don't hope for magical results.

So, if your print resolution is above 150 or 200dpi (please test as your mileage may vary), just send that data without resampling in LR.
If it falls below that threshold AND you found the driver doesn't interpolate properly, resample in LR by checking the appropriate checkbox above the profile.
You may set the resampled resolution to 300dpi as it should be the "native resolution" of an HP driver but for one I'm not sure of that, for two I'd doubt that any significant differences would show with the default 240dpi setting.