Read this and get back to me with any additional question: The Right Resolution.
OK, now you've done it, Jeff!
I thought I completely understood resolution, but decided to read your article anyway. Now, I'm confused, so I have a ton of questions for you. OP, sorry for semi hijacking the thread.
Aww heck, it's complete hijacking I guess...
I have an Epson 9900, which advertises a maximum of "SuperPhoto - 2880x1440dpi". Of course, on some materials such as canvas that can't hold as much detail, the maximum becomes "SuperFine - 720x1440dpi". Thought I had this perfectly figured out and understood. Then, your article refers to Epson as using 360dpi, or 720dpi if finest detail is checked.
Then, I realized I was confused.
1) I did some looking, and found a few places that said 2880dpi is really 720dpi but advertised that way because there's four colors. But, I couldn't tell if those sites knew what they were talking about, and they weren't talking about the 9900 which of course uses 10 inks at a time, and 360 nozzels per inch. So, what's up with the discrepency between the advertised higher dpi and the 360/720dpi you mention, which I can tell you're right about?
2) If the 2880 vs 720dpi has to do with the idea of a CMYK 4 color process, does this mean a 10 ink SuperPhoto actually creates a much higher dpi like 7200x3600dpi, but is just advertised as 2880x1440dpi to be comparable with a 4 color CMYK process?
3) Each "spot" is printed multiple times by multiple head passes. Is that how 360 nozzels per inch is creating these higher advertised dpi numbers? When it makes multiple head passes on the same spot, is it doing something like interpolating here to create smoothness, rather than just printing the same colors at the same spot to increase ink density?
4) Since there's only 360 nozzels per inch, how's fine detail bump it up to 720dpi? Does it just do twice as many head passes?
5) Since the 9900 advertises a 2880x1440dpi, if there's 360 nozzels per inch, are the actual nozzels ovalular rather than circular? Or since they're moving, does a circular drop smear against the media a little bit to make the resolution finer going along the length of the roll rather than along the width? Or, do each of the sets of 360 nozzels form a rectangle rather than a square?
6) If I have an image that's higher than the dpi it's going to be physically printed at, I would assume it's going to be downsampled either way, and that having Photoshop downsample it could use a better algorithm than whatever does it in the printing pipeline. Your article says not to downsample to get to the driver resolution. Could you shed light on why?
7) In the driver's quality options, does "Edge Smoothing" only help when you're letting the printing pipeline do the upsampling? I never let the pipeline do upsampling, so is this a useless option for me? (I never use it.)
8 ) Putting aside understanding why for a moment, if I'm printing at "SuperFine - 720x1440dpi", does upsampling to 360dpi gain the maximum benefit -- and is upsampling beyond that like to 720dpi or 1440dpi just a waste of time at best?
9) Likewise, if I'm printing at "SuperPhoto - 1440x2880dpi", does upsampling to 720dpi gain the maximum benefit -- and upsampling to
1440dpi or 2880dpi just a waste of time at best?
appreciate your original article and any responses you give. I always want to print my images at the highest quality possible, just because I can. I keep "High Speed" off, because shadows can get banding when using it on the 9900. I haven't used Finest Detail because I didn't understand that it doubled the resolution communicated to the driver. I've always upsampled to 1440dpi unless the print size is so large that I have to use 720dpi to keep my computer running...