Mike Chaney's Tech Corner

I am using an Epson Stylus Photo R2400 printer. On some types paper, you can set their quality setting to "Photo RPM" which is 5700x1440 dpi. In order to utilize this high resolution should I set the Qi Print Resolution setting to "OFF", since the highest resolution offered is 1440 ppi?

No.  You are confusing DPI and PPI.  The driver runs at 720 PPI and from there, the printer lays down individual dots at 5760x1440.  You should always leave Qimage's resolution set to Max which should be 720 to match the native driver PPI.  Remember that the driver has to use much higher DPI when laying down individual ink dots to make a print that is close to 720 PPI since each individual ink dot in that 5760x1440 can only be one of a few dozen colors (at most).  In other words, the driver is operating at 720 PPI and it takes 5760x1440 resolution to approximate a color print at that 720 PPI.

Regards,
Mike

Thanks Mike - how does your "Overdrive" setting of 1440ppi come into play? Is that no better than the native 720?

Overdrive is for prints that are intended to be viewed under magnification or ones that require detail beyond unaided eye viewing.  Lenticular prints would be a good example.

Regards,
Mike

For my Epson R1900 Qimage Ultimate gives me choices for Overdrive, 720, 360, 240 and 180.
What happens if I choose 360 ppi but in the driver I choose "Best Photo"? What dpi will I get?

DPI are the dots laid down by the printer driver so the PPI ("resolution" in Qimage) won't affect the DPI in the driver: you get whatever DPI is selected in the driver.

Mike

Thanks for your fast reply. Unfortunately I'm having trouble understanding. So, does Qimage do anything different if I select 360 ppi instead of 720?
Thanks for your patience.

Going into the broad topic of PPI vs DPI is not something I want to cover here.  You can search PPI vs DPI and find articles and videos online and pick one that suits your time and the level of detail you want.  In a nutshell, PPI and DPI are related but not the same.  PPI ("Resolution" in Qimage) is the amount of detail you want to send to the printer.  DPI is selected in the driver and controls how fine the grain (dot pattern) is when the printer actually spits out the ink.  It takes multiple dots (DPI) to truly reproduce one pixel (PPI) so think of DPI as "how hard you want to run your printer" and PPI as "how much detail you want to send to your printer".

It's usually best to select "Max" for "Resolution" in Qimage because "Max" is always the PPI that the driver is requesting and should be optimal for the current driver settings.  Any setting other than "Max" in Qimage will send either more or fewer pixels than the driver "wants".  Qimage asks the driver what PPI (level of detail) it wants you to print and the answer is returned in the "Max" setting in Qimage's Resolution entries.  If you see "Max - 720 PPI", it means the driver thinks 720 PPI is best for the current paper and quality chosen in the driver.  If you see "Max - 360 PPI" it means the driver thinks 360 PPI is best: you might see a lower number like that if you are printing a very large print, you have chosen a lower quality in the driver, etc.

Regards,
Mike

I believe I'm not wording my question correctly. What I mean is what does QImage do differently if I set the PPI Res to 360 ppi or If I set it to 720 ppi?
Does it resample the image? Just tells the driver to use either 360 or 720? or does it ignore the setting in Print Res?

Qimage will send the image at the resolution shown.  So if you set it to 360 PPI, it'll send the image at 360 PPI.  If set to 720 PPI, it'll send the image at 720 PPI.  Unless your image happens to already be the resolution shown (at the given print size), it'll resample.  If it didn't resample, the driver would do it for you... and you want Qimage to do the resampling and not the driver.  Qimage has higher quality resampling routines.

Mike

Thank you very much for your explanation. I believe now I know how to use QImage. Which, I believe is vastly superior to Lightroom when it comes to printing.
Also thank you very much for your patience.