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Author Topic: Image Capture PPI and a couple other questions  (Read 2290 times)
One Frame at a Time
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« on: August 09, 2012, 10:41:17 PM »
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Did a search and could use a little help:

Only run a couple of prints on my new 3880.  I am running a calibrated monitor (NEC Spectraview WUXI).  So far the prints look good from a color standpoint, but have other problems that make them destined for the trash.  Hoping to lessen the size and number of prints that go in the recycling bin.....
 
What is the thinking today on raw image ppi necessary for a good print at 360 dpi (Epson).  I have a heavily cropped image.  Its down to 97 dpi in the Print Module.  Capture quality is good but image has a lot of fine detail (18MP crop sensor camera in RAW)  Is that enough to make a good print, letting LR res up to 360 dpi?  (I am using luster type papers if that is a consideration)

Epsons "Layout" tab has sections that are confusing and not discussed in the manual.  One is "Paper Size" and the other is "Output Paper Size"??  They are related but I don't understand why this is even in the driver.  I'd like to understand the purpose.

Now that I am running a bigger format (only 17 inches but who wants to waste money and resources) I was wondering what more experienced people do to hard proof their images before running a large print?  Do you print a 8x10?   Is there an easy way to print just a section on half a sheet of 8x11 paper so you can see how the grain/noise and detail will look at your intended print print size??

Thanks!,

Paul

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« Reply #1 on: August 09, 2012, 11:04:30 PM »
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What is the thinking today on raw image ppi necessary for a good print at 360 dpi (Epson).

Read this and get back to me with any additional question: The Right Resolution.
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darlingm
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« Reply #2 on: August 10, 2012, 01:33:10 AM »
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Read this and get back to me with any additional question: The Right Resolution.

OK, now you've done it, Jeff!  Smiley  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.  Smiley  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?

I really 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...
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Ernst Dinkla
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« Reply #3 on: August 10, 2012, 03:24:15 AM »
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If you start to realise that the dot distribution on the print is expressed in dots per inch DPI and usually has numbers like 1440, 2880, 5760 you can forget how that is achieved. In principal an inkjet head with just one nozzle can already lay down a pattern like that if the XY stepping is as fine as 1/5760 inch. That the heads have more nozzles with related resolutions does not matter, it just speeds up the printing and makes full color printing possible.

The other thing is the preferred printer driver input resolution (often called native resolution) expressed in pixels per inch PPI and the usual numbers are 360, 720. Lower numbers but those pixels contain the total color information in either 24 or 48 bits, the printer has to lay down that information with at least 4 different colored inks and for each either smaller or bigger droplets, more or less droplets, more or less diluted ink droplets etc. The droplets creating a complex dot matrix with a resolution described above that represents one pixel. If the driver print quality settings are kept low, for example resulting in a 1440x1440 DPI print resolution then the driver will ask for 360 PPI input. A choice that would be made for a lower grade paper. Higher settings will ask for a higher PPI input. There is a relation between the preferred (native)  input PPI numbers and the DPI print resolutions of say 2x or 4x but that is only because it makes the complex computing in the driver easier, a software programming choice. If the user wants to send an odd PPI number like 207 PPI from the application to the driver then either the application or the driver upsamples that  to 360 PPI or 720 PPI and then the driver starts to use its normal data processing to form dot matrices. For the user the 360 and 720 PPI input resolution numbers are the thing to remember, some applications like Qimage Ultimate show that number to the user, some drivers like the HP Z models drivers show it near the print quality settings (300 and 600 PPI though, the HP resolution numbers).

Four pages of articles where you can find the right information on how to get your image data on paper:

http://ddisoftware.com/tech/articles/


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Schewe
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« Reply #4 on: August 10, 2012, 05:40:59 AM »
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I really 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.

All of your questions are really answered in the article...you may need to reread it again to answer 1-9. If not, ask the specific question. I don't do well trying to answer multi-point questions really well...I tend to look at the questions and have my eyes glaze over and screw this and go away...
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Tony Jay
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« Reply #5 on: August 10, 2012, 06:11:21 AM »
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Jeff's article does answer the REAL questions.
I read it and realized that I had already seen it before.

Getting too excited about exactly how the print head lays down ink is a blind alley of fruitless pursuit.
All one really needs to know is the the printer is laying down plenty of "dots" of ink for each "dot" representing the native resolution of the image being printed.

If you want good quality (fine detail) prints just simply uprez your images in the manner suggested by Jeff - in Lightroom it is an absolute breeze.

Regards

Tony Jay
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BartvanderWolf
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« Reply #6 on: August 10, 2012, 06:18:06 AM »
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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.

Things may be simpler than you think.

Printer drivers send their pixel data to the printer, and in that process they translate the pixel data to printer dither data, or dots. The printer needs to dither the pixel data to produce intermediate colors and brightnesses by mixing background/substrate color with a limited number of fixed ink colors.

The physical placement of those dots/droplets can be very accurate, and the dots may partially overlap with other dots or even be superimposed in order to blend colors. This is achieved by a mechanical offset of the printhead and/or the paperfeed mechanism with distances that are potentially smaller than the print nozzle distance, and sometimes combined with variable dot sizes by varying the amount of ink which produces different droplet sizes. This physical placement accuracy is influenced by the driver settings, and it translates the pixel color in a dithered pattern of smaller dots.

The printer driver has a native maximum pixel resolution, usually 720 PPI (indeed Pixels per inch) for Epson printers, and 600 PPI for Canon/HP printers, but it may require activating a driver setting to actually allow printing that many pixels. Without the proper settings, the printer may upsample or downsample the pixel quantity to 360 PPI (or 300 PPI).

The resampling quality of the printer driver is usually not very good, so it's best to do it yourself (with good software) or an application that does this well as an integral part of it's output workflow.

Once you make the distinction between the image's pixel resolution (which you can control by providing the required number of pixels for the output size), and the mechanical dot placement accuray (which can be influenced by a number of driver settings), things should become easier to understand.

Cheers,
Bart
« Last Edit: August 10, 2012, 06:37:45 AM by BartvanderWolf » Logged
One Frame at a Time
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« Reply #7 on: August 10, 2012, 09:38:47 AM »
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Hey, you guys really know how to hijack a thread Smiley  Jeff, thanks for that article.  It touched on what I wanted to know about my image (viewing distance to resolution relationship), but left my question unanswered. 
I am at a native camera capture resolution of 97 ppi when sizing my image to 12x18 inches.  LR is set to up rez to 360.  Is there enough data in the cropped capture to make a decent print?  I realize there are many variables and grey areas in this question.  Is 97 ppi enough to warrant a try? 

Also, would REALLY like to know how people with a lot more - Paper and Ink in the game, ramp up to full 24 or 44 inch prints.  Do you do any hard proofing at smaller sizes before going full size?  If so, would you mind sharing your workflow?   

Thanks!

Paul
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Randy Carone
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« Reply #8 on: August 10, 2012, 09:54:23 AM »
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Paul,

Uprez then crop a section in PS and print it to 8½x11, or a portion of 8½x11, and you should be able to do a couple of proofs on one sheet. Try the LR uprez, from your original 97 PPI and print. Then uprez in PS to 180 and let the driver uprez. Finally, uprez to 360 in PS and print and see which one looks better.
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« Reply #9 on: August 10, 2012, 10:11:06 AM »
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Hey, you guys really know how to hijack a thread Smiley  Jeff, thanks for that article.  It touched on what I wanted to know about my image (viewing distance to resolution relationship), but left my question unanswered.  
I am at a native camera capture resolution of 97 ppi when sizing my image to 12x18 inches.  LR is set to up rez to 360.  Is there enough data in the cropped capture to make a decent print?  I realize there are many variables and grey areas in this question.  Is 97 ppi enough to warrant a try?  

Also, would REALLY like to know how people with a lot more - Paper and Ink in the game, ramp up to full 24 or 44 inch prints.  Do you do any hard proofing at smaller sizes before going full size?  If so, would you mind sharing your workflow?  

Thanks!

Paul


Looks like you are starting with a really small file.
Time for some resampling in Photoshop or Perfect Resize. At least this is how we do our canvas.
Resampling first in Perfect Resize then uprezing before printing in Lightroom.
12 x 18 @ 180 to 360 ppi or a max of 200%. Perfect resize shows you that percentage number right at the top of the page.
In the print module in Lightroom the print preview will show your native resolution .
 I would still check the print resolution box and uprez  50% above native when printing in Lightroom.
« Last Edit: August 11, 2012, 05:35:45 AM by Dan Berg » Logged

Ken
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« Reply #10 on: August 10, 2012, 11:28:18 AM »
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After reading a lot of books, online discussions and excellent LL tutorials, I did some testing to confirm my understanding of it, and have stuck with it since then. I always send 16-bit (when possible) 360ppi from Photoshop to the printer (Epson 7900).

Coming from about 40 years of "wet darkroom" printing, I apply a similar approach to test prints.
  • Test on the same medium (paper, canvas etc.) as the final.
  • Save your image (without flattening if layered), and keep it open.
  • Flatten your image if layered and apply sharpening if you like.
  • Open a new image file and size it to a "test strip". (I use 6" height.)
  • Set up your test strip exactly as your image file (profile, ppi, etc.).
  • Select important parts of the image that you want to see printed and drag them to your test strip.
  • Print, or continue...
  • Save your test strip if you want to try various profiles, media, tweaks, sharpening, etc.
  • You can print multiple test strips (depending on media size of course) on one print run if you want to.


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One Frame at a Time
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« Reply #11 on: August 10, 2012, 12:56:53 PM »
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Thanks again everyone.  I was wondering if incremental rezing up was still part of the workflow.  I have been smitten with Lightroom and have not opened photoshop in nearly a year for image manipulation.  Thought with all the fancy stuff they added to LR that maybe this was passe.

FWIW, here is the image I want to print.  I was shooting landscapes when I spotted this Coyote.  I had my 24-105 mounted.  Shot a few hail Mary's as he was pretty far away.  What makes this special is all the prairie dogs standing just behind him.  Did not even know they were there till I started to look closely at the image on my computer....

http://www.paulpodellphotography.com/Fine-Art-Landscapes-and/Fine-Art-and-Landscapes/1255210_PZnwvJ#!i=2017521246&k=hWbsgFB&lb=1&s=A

Thanks again,

P.
« Last Edit: August 10, 2012, 01:01:14 PM by One Frame at a Time » Logged
One Frame at a Time
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« Reply #12 on: August 10, 2012, 01:02:20 PM »
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Not sure why but the link does not take you right to the image I want to show.  See attached:
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darlingm
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« Reply #13 on: August 10, 2012, 03:19:19 PM »
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All of your questions are really answered in the article...you may need to reread it again to answer 1-9. If not, ask the specific question. I don't do well trying to answer multi-point questions really well...I tend to look at the questions and have my eyes glaze over and screw this and go away...

Understood, I wrote you a lot.  Smiley  I've re-read your article and done a bunch of other reading.  Hoping these two "to sum it up" questions will be OK.  Smiley

A) Image resolution is higher than hard cap of 360/720 being used.  Why shouldn't you downsample the image to the hard cap?  If you don't, isn't that happening anyway in the driver/pipeline?

B) Image resolution is lower than hard cap that you're using.  For highest technical quality, ignoring if there's a visible difference, should you always upsample the image to 720ppi and use finest detail?  Even if you're printing on canvas that maxes at SuperFine 720x1440dpi?  Or, since 720x1440dpi refers to dots and there will be multiple dots per pixel, is using a hardcap of 7200ppi overkill -- even on a technical image quality basis?
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darlingm
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« Reply #14 on: August 10, 2012, 03:35:28 PM »
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Thanks again everyone.  I was wondering if incremental rezing up was still part of the workflow. . .

Someone may disagree, but it's my understanding with modern resampling methods, incremental rez'ing up is in the past.  If you're working with images that need to be upsampled quite a bit, I recommend looking into Perfect Resize (previously called Genuine Fractals.)  It can produce better results than Photoshop when you're pushing it a bit.

As far as workflow having to do with large images... I've gotten to the point with a calibrated/profiled professional color monitor (Asus ProArt PA246Q - yes there are better but this one's only $460) that with some images I'm just going to the full size print.  With others, I sometimes do small test strips like others have mentioned.  You'll get a feel of when you're expecting there might be an issue vs when you know it should turn out OK.  If I'm not that picky about it, I might only do a 1" x full length strip.  When you're printing multiple versions using different methods for comparison, I recommend labeling them in the image.  If I have the room, I'll type out what was done to it.  If I don't want to take up that space, I just letter them.  I cut each version out borderless, and it would be easy to forget which was which otherwise.

If you have a program like Colorthink Pro that can let you really compare color gamuts, you can choose to do the test strips on a cheaper paper if the color gamut is a very close match.  It's discontinued now, but Breathing Color had a paper called 30MS which was incredibly inexpensive, had optical brightners, and wasn't even close to being archival, but the color gamut with their OpticaOne/Pura Smooth archival paper was a close enough match, that I often printed tests on the cheaper 30MS.
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Mike • Westland Printworks
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luxborealis
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« Reply #15 on: August 10, 2012, 03:46:48 PM »
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Getting back to one of your original questions...

I was wondering what more experienced people do to hard proof their images before running a large print?  Do you print a 8x10?   Is there an easy way to print just a section on half a sheet of 8x11 paper so you can see how the grain/noise and detail will look at your intended print print size??
Thanks!,
Paul

I, too, was once a wet darkroom worker and have co-opted the good old test strip as a check prior to printing full-page photographs. In the Lightroom Print module, I created printing pre-sets to print successive 3" strips of an image on a single sheet. In Print, dragging the image shown in the test strip window will allow you to select which section of the image you want to print in the test strip. That same strip will print in the 2nd test trip you make. I've attached to screen shots showing Test Strip 1 and 2. Of course, when you go on to your next image to print, the rest of the sheet is available for subsequent test strips.

Conceivably, you could just as easily print smaller, full image test prints (e.g. on 8-1/2 x 11), but I have found that having a strip of the full-size image is more helpful, since I can also check perceived sharpness as well as colour balance, brightness and contrast.

–Hope this helps.

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AFairley
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« Reply #16 on: August 10, 2012, 07:12:06 PM »
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I tend to print 5x7 proofs, I cut sheets to that size out of 17x22 or from scrap from cutting 24x32 down to 17x25, it's easier for me to compare versions that way, but perceptually, the full size 17x22 will appear to be a little lighter than the same image printed on 5x7.

I find that if my image is below around 120 ppi at my target print size of 17x22 the final print is pretty marginal.  I don't have a problem with 180 ppi which is about where my files usually come in, usually just a tad below.

I uprez to 360 ppi before sending the image to the printer.  I do find that uprezzing to 360 ppi at target size using Genuine Fractals or Alien Skin Blow Up gives me better prints from the 3880 than letting LR do the uprezzing to 360 (or specifying uprezzing at all).  From LR, I can see jaggies on some diagonals (admittedly with close inspection of the prints), I do not see that with the prints uprezzed with GF or AS.  If someone can show me how to equal what GF and AS do in LR, I would be happy, since it would be slightly more convenient.  However, I believe that what I am seeing is a limitation of the bicubic algorithm compared to whatever GF and AS use.  Again, I'd be happy to be proved wrong, but that's my experience so far.
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BartvanderWolf
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« Reply #17 on: August 10, 2012, 07:32:44 PM »
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From LR, I can see jaggies on some diagonals (admittedly with close inspection of the prints), I do not see that with the prints uprezzed with GF or AS.  If someone can show me how to equal what GF and AS do in LR, I would be happy, since it would be slightly more convenient.  However, I believe that what I am seeing is a limitation of the bicubic algorithm compared to whatever GF and AS use.  Again, I'd be happy to be proved wrong, but that's my experience so far.

You are correct, LR's upsampling is limited by the algorithm(s) used. Personally I use PhotoZoom Pro, similar to what AS produces but with less 'sharp corner rounding' artifacts. GF (renamed to PR Wink ) generates too much posterization like results (it loses the 3-dimensionality of smooth gradients) for my taste.

Cheers,
Bart
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AFairley
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« Reply #18 on: August 11, 2012, 12:06:02 AM »
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You are correct, LR's upsampling is limited by the algorithm(s) used. Personally I use PhotoZoom Pro, similar to what AS produces but with less 'sharp corner rounding' artifacts. GF (renamed to PR Wink ) generates too much posterization like results (it loses the 3-dimensionality of smooth gradients) for my taste.

Cheers,
Bart

Thanks Bart, I will try out their demo.  I like the impasto look GF tends to impart, but it does not work for all images.
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« Reply #19 on: August 11, 2012, 03:00:45 AM »
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A) Image resolution is higher than hard cap of 360/720 being used.  Why shouldn't you downsample the image to the hard cap?  If you don't, isn't that happening anyway in the driver/pipeline?

If your image's native resolution is above 360 but below 720, I would upsample because there is no benefit from downsampling to 360 but I've seen benefit from upsampling to 720 (and using Finest Detail). In any event I don't think there's a good reason to downsample ay image just to hit some sort of magic number...why throw away pixels?
Quote
B) Image resolution is lower than hard cap that you're using.  For highest technical quality, ignoring if there's a visible difference, should you always upsample the image to 720ppi and use finest detail?  Even if you're printing on canvas that maxes at SuperFine 720x1440dpi?  Or, since 720x1440dpi refers to dots and there will be multiple dots per pixel, is using a hardcap of 7200ppi overkill -- even on a technical image quality basis?

The article I wrote indicates the printer rez ratio is relevant for glossy type papers. I didn't test watercolor or canvas since I don't really print on that stuff. The odds are that exceeding 360 and using Finest Detail won't benefit from 720 PPI output with Finest Detail on because the papers/canvas can't hold the detail.

In any event, you should be testing this stuff yourself on your images, your printer & paper combo. All I can do is tell you what I've found after doing that testing myself.
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