DPI

[csm]

I'm confused. When the Epson 9900 resolution is 2880 x 1440 dpi it means 2880 droplets wide by 1440 droplets high. Is this in a square inch?

Thanks

[Ryan Mack]

The i in dpi is for inches, so yes that’s 2400 by 1200 across and down a square inch. That’s the number of ink dots though, Not pixels in your image. That’s either 360 pixels per inch or 720 pixels per inch if you click “highest quality”.

[csm]

Thanks, I knew the PPI vs  DPI difference. I was still a little confused on the square inch part. I thought that the W X H DPI would be the same(for example 2880 x 2880 vs 2880 x 1440), but for some reason it is not.

Thanks

[Bart_van_der_Wolf]

Thanks, I knew the PPI vs  DPI difference. I was still a little confused on the square inch part. I thought that the W X H DPI would be the same(for example 2880 x 2880 vs 2880 x 1440), but for some reason it is not.

Hi,

Indeed, it may look a bit strange, but it is due to the physical layout of the ink nozzles in one dimension, and the paper-feed mechanism in the other dimension.

The ink nozzles have a fixed distance between them, and the firmware allows to chose whether they are all used or not (and there are probably multiple rows of nozzles with a half nozzle offset between rows). The paper feed distance is probably controlled by the active nozzle selection. All are adjusted for an optimally smooth and interwoven pattern between head passes, and an optimal number of mixed color dots to produce the intermediate ink and output-medium blended colors at the larger pixel level.

Cheers,
Bart

[jrsforums]

The i in dpi is for inches, so yes that’s 2400 by 1200 across and down a square inch. That’s the number of ink dots though, Not pixels in your image. That’s either 360 pixels per inch or 720 pixels per inch if you click “highest quality”.

360/720 for Epson

[shadowblade]

360/720 for Epson

Not with the P10000/P20000. They're back to 300.

[Bart_van_der_Wolf]

Not with the P10000/P20000. They're back to 300.

And 600, with 'finest details' selected.

Cheers,
Bart

[jrsforums]

Not with the P10000/P20000. They're back to 300.

Guess it just proves that one needs to be specific about the info given.....me included.

[csm]

Jeff Schewe says the Epson 9900 has 3600 vertical x 10 horizontal nozzles. I had the printhead of my 9900 replaced and it hast 5 rectangular squares on the printing side. Each printing plate has two ink inlets on the back, and on the print side plates, I can not see the holes where the ink comes out from. I was trying to find out how the nozzles were placed. I guess I'll need a microscope to do that.

Thanks

Hi,

Indeed, it may look a bit strange, but it is due to the physical layout of the ink nozzles in one dimension, and the paper-feed mechanism in the other dimension.

The ink nozzles have a fixed distance between them, and the firmware allows to chose whether they are all used or not (and there are probably multiple rows of nozzles with a half nozzle offset between rows). The paper feed distance is probably controlled by the active nozzle selection. All are adjusted for an optimally smooth and interwoven pattern between head passes, and an optimal number of mixed color dots to produce the intermediate ink and output-medium blended colors at the larger pixel level.

Cheers,
Bart

[Dan Wells]

Canons are 300/600 (the actual nozzle density is 2400, and they use either 4x4 or 8x8 to form an image pixel). Variable dot size complicates all of this - but the number to remember for photography is...
300 (Canon, Epson 10000/20000, HP?)
360 (many Epsons)
600 (Canon &co. with highest detail on)
720 (some Epsons with highest detail on).

Dan

[Ryan Mack]

Hey Dan, on the topic of variable dot size, if I remember correctly the Epson only have variable dots at 360ppi and disabled at 720ppi. Do you know if the same is true for Canon? Thanks, Ryan

Canons are 300/600 (the actual nozzle density is 2400, and they use either 4x4 or 8x8 to form an image pixel). Variable dot size complicates all of this - but the number to remember for photography is...
300 (Canon, Epson 10000/20000, HP?)
360 (many Epsons)
600 (Canon &co. with highest detail on)
720 (some Epsons with highest detail on).

Dan

[unesco]

There are two aspects - dot size and dot placement accuracy. You can have big dots but their placement resolution can be theoretically "higher" than their size.
In 1440x720 the first number represents vertical resolution (paper feed steeping). Comparing to 720x720 that will have 2x more print head passes --> ~2x slower.

[Farmer]

Hey Dan, on the topic of variable dot size, if I remember correctly the Epson only have variable dots at 360ppi and disabled at 720ppi. Do you know if the same is true for Canon? Thanks, Ryan

Drop size options relate to output resolution, not input resolution.

[csm]

Thanks.

There are two aspects - dot size and dot placement accuracy. You can have big dots but their placement resolution can be theoretically "higher" than their size.
In 1440x720 the first number represents vertical resolution (paper feed steeping). Comparing to 720x720 that will have 2x more print head passes --> ~2x slower.