The Epson RPM quality option - does it offer a benefit ?

[Ink stained Fingers]

Epson photo printers offer an option 'RPM' for the quality settings, Epson calls it 'Resolution performance Management' but what does it do ?
Epson photo printers typically print with a print resolution of 720 dpi - image pixels per inch but an Epson driver does not tell the user in detail which droplet sizes are used, the number of print passes and even the active print resolution is not visible to the user in most cases. Qimage makes an exeption here and shows the print resolution depending on the driver settings e.g. 240 - 360 - 720 dpi. The actual color of each image pixel - dot - is rendered to create the correct color for this pixel - this with a finer print resolution up to 5760x2880 dpi.

I did some test prints with a small test image by Roger Clark published longer time ago

It prints small color bars with line widths with 1 - 6 pixels width if it is printed with a matching print
resolution. The above image is scaled for 720x720 dpi in the image characteristics, and Qimage has
a print option - 'print with this embedded resolution' to make it simple, the prints with this resolution have a size of 10x18 mm - pretty small overall.
I'm printing it with an L800, a P50 like 6 color printer as an L-series ink tank model, with 1.5 pl dropsize min.
I'm printing with the paper selections - matte paper or Ultra Glossy Photo paper, with both the Photo and the RPM quality settings. Qimage reports a print resolution of 720 dpi in all cases but the driver does not tell me any more details. I'm doing all sample prints on the same type of glossy paper and take macro photo shots to get the details. The images below are reduced in resolution and may carry some jpeg compression artifacts but the differences are clear enough. I'm not testing the printing speed at this time, and don't measure variations of the gamut with these driver options either

This is the printout with the matte paper setting - photo quality

This is the printout with the matte paper setting - with the RPM option , these shots are highly
magnified, the actual print has a size of 10x18 mm

The print looks much cleaner, the small letters of the internet address are readable,

this is the printout with the Ultra Glossy paper selection - photo quality option

This one looks pretty good, better than with the matte paper setting,
and this is the last print with the RPM setting - Ultra Glossy paper setting

It looks identical to the printout with the matte paper setting.
The printer can print lines with 1 pixel width but the ink dots are bleeding slightly, so
a 1 pixel line pattern cannot be resolved, alternating line patterns 2 pixels wide are
on the edge of becoming visible. Other resolution tests with a Siemens star show that
the acheivable resolution with inkjet printers is in the range of 300 - 320 dpi, Epson
and Canon are pretty close together; the coating of the photo paper influences
the amount of ink bleeding to a degree and have an impact onto this effective resolution as well,
but would be subject of a separate test.

 

[The Hat]

How does this look, it’s done on my Maxify, plain paper, standard setting, and pigment ink...?
click to enlarge..
and this is on the iP4500 same setting with dye ink.. What am I looking for... ?

And no Mustard used...

 

[Ink stained Fingers]

At @The Hat - what is the size of your printouts - somewhat larger than 10x18 mm I would expect ?

 

[The Hat]

what is the size of your printouts

Same size printed, 12 x 7 cm...

 

[Ink stained Fingers]

Same size printed, 12 x 7 cm

That explains the clean print - you would need to scale down your test prints to about stamp size, I'm printing at 720dpi on 10 x 18 mm, if you print with Canon typical 600 dpi it'll go up slightly to 13 x 21 mm . I don't know which program you are using for printing and how to scale the print output to these dimensions.

I print with 720 dpi with these file properties

wtih Canon's genuine print resolution of 600 dpi you would get these parameters

 

[PeterBJ]

The test image is found on this page. You can right-click and save it.

When printed using normal plain paper settings on a Canon MP970 the result is a print of 18x10 cm meaning 10 times too big. Printing at a 10 % scaling produces a print of 18x10 mm. Here is a 1200 dpi scan of the 18x10 mm print:

 

[Ink stained Fingers]

Please find a way to eliminate any rescaling of the image - within your graphics program or the driver, the size of 10x18 mm is approximate - the image I posted above has a width of 500 pixels, printing 500 pixels at 720 dpi does give you a fractional number of 17,64 mm, any smoothing, any sharpening , up/downscaling etc should be turned off - 1 image pixel should print as one pixel by the printer, such options are sometimes hidden in the printing program and overlooked - Thumbsplus calls this option 'Print res. 1:1' , Qimage has an option to print with the embedded resolution, I'm not familiar with other programs.
Changing driver/printing options have an impact onto the printing time, this little test image allows you to do a quick test whether any upscaling of quality settings really give you a benefit you want to wait for, it may not matter very much when you print a few images , but if you print 100 sheets for an album it makes a difference waiting an hour or so or the whole afternoon until the printer prints the last sheet.

 

[The Hat]

OK try this, I reduced both down to 15%..

they are both 21 x 11 mm...

Here they are again reprinted at 15%, scanned and posted

this time they are 25 x 14 mm..