Up-Rezing or Down-Rezing an image

[JB Rasor]

I've been printing photos, on the Epson 3880, using the advice Michael and Jeff have advocated (that is if an image is below 360ppi, up sample to 360ppi, and if it is over 360 up sample to 720ppi).  

However, I've seen individuals advocate down sampling to achieve a larger print size...using Photoshop instead of Lightroom. In other words, taking a resolution down to 120ppi to achieve a 40 inch print for example. Is it best to always aim for 360 or 720ppi when Epson printers are concerned? Or is down sampling something to consider?

I'm doing an MFA in photography right now, and the individual suggesting down sampling is the head equipment tech (printers, etc.) I'm thinking he is wrong, but is he?

Thanks everyone!

JB Rasor

[Bart_van_der_Wolf]

I've been printing photos, on the Epson 3880, using the advice Michael and Jeff have advocated (that is if an image is below 360ppi, up sample to 360ppi, and if it is over 360 up sample to 720ppi).

Hi JB,

In general (depending on the driver settings), that is correct. If you don't resample then the printer driver will (to either 360 PPI, or 720PPI with the finest detail setting on). The algorithms that the printer driver uses are made for speed, not for quality, so you can do a better job with dedicated resampling. That has the added benefit that you can 'output sharpen' at the final output pixel size.

Lightroom usually does a better resampling job than Photoshop, unless you use dedicated resampling (Photozoom Pro, Perfect Resize) and sharpening (Topaz Detail, FocusMagic) plug-ins in Photoshop.

Cheers,
Bart

[Mark D Segal]

Hi JB,

Bart, Michael and Jeff are correct.

Printing at a resolution of 120 will show degraded image quality. As a student in digital imaging, however, you should not just take anyone's word for it. These things are so easy to test for oneself. Do what the printer tech recommended, look at the results on paper compared with the preferred way of doing it and examine the prints to see if you can tell the difference. I'll bet comparing 120 with 360 you really will see it.

I use an Epson 4900 and before that a 3800, a 4800 and a 4000, as well as all the corresponding versions in their time of Lightroom and Photoshop; I periodically run sanity checks on resolution outcomes. I can print down to 180 and get barely acceptable results. Below this I find quality becomes unacceptable. Upwards of 240 is usable and for Epson professional printers, 360 or 720 as they recommend is optimal - doing the up-sizing in Lightroom.

[jrsforums]

I've been printing photos, on the Epson 3880, using the advice Michael and Jeff have advocated (that is if an image is below 360ppi, up sample to 360ppi, and if it is over 360 up sample to 720ppi).  

However, I've seen individuals advocate down sampling to achieve a larger print size...using Photoshop instead of Lightroom. In other words, taking a resolution down to 120ppi to achieve a 40 inch print for example. Is it best to always aim for 360 or 720ppi when Epson printers are concerned? Or is down sampling something to consider?

I'm doing an MFA in photography right now, and the individual suggesting down sampling is the head equipment tech (printers, etc.) I'm thinking he is wrong, but is he?

Thanks everyone!

JB Rasor

The decision on 360ppi or 720ppi is reasonable.  However, if you have not selected 'Finest Detail' in the print driver, the driver will not use the 720ppi, but will downres it to 360.  Conversely, if you have select Finest Detail and send it 360ppi, it will uprez it to 720....which could have been done much better on the computer.

[JB Rasor]

Thanks very much guys. That clears up a lot. Mark, I'll definitely try some test prints and see what the results look like.

John, I haven't been using the Finest Detail check box, even when printing at 720ppi. I'm assuming I should start checking that box when I do up sample to 720ppi via the Lightroom print module? However, leave it unchecked when printing at 360ppi? Does that sound correct?

Thanks again! Have a great weekend everyone!

JB

[Bart_van_der_Wolf]

I'm assuming I should start checking that box when I do up sample to 720ppi via the Lightroom print module? However, leave it unchecked when printing at 360ppi? Does that sound correct?

Correct. Leaving the 'finest detail' box unchecked will make the printer driver always resample to 360 PPI (unless output is already at that resolution). checking that box will always resample to 720 PPI (unless output is already at that resolution).

Cheers,
Bart

[Pic One]

Correct. Leaving the 'finest detail' box unchecked will make the printer driver always resample to 360 PPI (unless output is already at that resolution). checking that box will always resample to 720 PPI (unless output is already at that resolution).

Cheers,
Bart

From what I've read, if one is looking for a set-it-and-forget-it option, if you always send 720ppi (for any print size) and click finest detail, there is nothing detrimental happening to your print output.    Of course it slows down the processing/print process a bit.

[Pic One]

However, I've seen individuals advocate down sampling to achieve a larger print size...using Photoshop instead of Lightroom. In other words, taking a resolution down to 120ppi to achieve a 40 inch print for example. Is it best to always aim for 360 or 720ppi when Epson printers are concerned? Or is down sampling something to consider?


JB Rasor

Not sure this was specifically addressed.. but I would NEVER advocate resampling a photo to a lower resolution in order to print larger.   This makes no sense at all.  As a general practice you should (if we're talking Epson printers), resample up to the nearest of these integers before sending to print:  120/180/240/360/720.  Or resample yourself all the way to 360ppi if you wish.    For example, If you have a 144ppi image at say 40x60 inches, I would never advocate resampling to 120ppi at the same size..  you'd be much better off upsampling to 180.  No sense throwing away pixels.

[PeterAit]

I expect the tech is just expressing it poorly. You would never actually "down-rez" for printing (reduce the total # of pixels in the image), but if you increase the print size the pixels/inch will indeed decrease. Thus, an image that measures 2400 x 3000 pixels is 300 ppi when printed 8 x 10" but 150dpi when printed 16 x 20". But, this is not down-rezzing, it's just arithmetic.

[JB Rasor]

You're probably right Peter, that the tech wasn't clarifying his comments, rather just showing me the ropes. He has no idea if I have a printing background or not. But that topic I think I have a good handle on now.

However, the Finest Detail checkbox is throwing me for a loop. Am I correct in saying that: If I have an image that is 480ppi, but I upsample to 720ppi in the Lightroom print module, it will still print at 360ppi because I haven't checked the Finest Detail Box?
Is the image than effectively being downsampled in the print pipeline, or has Lightroom done an upsample and the printer is simply printing at 360ppi?
I'm probably making it more confusing than it needs to be, but I always heard Finest Detail wasn't for photographs but vector graphics.

[ErikKaffehr]

Hi,

Epson is printing at 360PPI unless you check finest details in which case it prints at 720 PPI.

So the rules are simple:

- If you have less than 360 PPI native resolution upres to 360 PPI using a good algorithm and print without finest detail.

- If you have more than 360 PPI native resolution upres to 720 PPI  using a good algorithm and print with finest detail checked.

The reason is that you want to print at either 360 PPI or 720 PPI, and would use a good algorithm, instead letting the printer driver rescale the image using a quick and dirty algorithm. But you may need good vision and/or a loupe to see the difference :-)

You're probably right Peter, that the tech wasn't clarifying his comments, rather just showing me the ropes. He has no idea if I have a printing background or not. But that topic I think I have a good handle on now.

However, the Finest Detail checkbox is throwing me for a loop. Am I correct in saying that: If I have an image that is 480ppi, but I upsample to 720ppi in the Lightroom print module, it will still print at 360ppi because I haven't checked the Finest Detail Box?
Is the image than effectively being downsampled in the print pipeline, or has Lightroom done an upsample and the printer is simply printing at 360ppi?
I'm probably making it more confusing than it needs to be, but I always heard Finest Detail wasn't for photographs but vector graphics.

[Bart_van_der_Wolf]

However, the Finest Detail checkbox is throwing me for a loop. Am I correct in saying that: If I have an image that is 480ppi, but I upsample to 720ppi in the Lightroom print module, it will still print at 360ppi because I haven't checked the Finest Detail Box?

Yes!

Is the image than effectively being downsampled in the print pipeline, or has Lightroom done an upsample and the printer is simply printing at 360ppi?

When Lightroom upamples to 720 PPI (and optionally sharpens at that resolution), the printer driver will downsample again to 360 PPI (and lose most of the sharpening or, what's worse, create artifacts) when the 'Finest detail' option is not selected.

I'm probably making it more confusing than it needs to be, but I always heard Finest Detail wasn't for photographs but vector graphics.

That misunderstanding was propagated for a long time (see here and here for how some of the insights developed), until people started to actually try it. The point is that the difference for regular image content may be small, but it does allow to gain resolution for fine detail, especially after sharpening at 720 PPI.

Cheers,
Bart

[Pic One]

Yes!

When Lightroom upamples to 720 PPI (and optionally sharpens at that resolution), the printer driver will downsample again to 360 PPI (and lose most of the sharpening or, what's worse, create artifacts) when the 'Finest detail' option is not selected.

Cheers,
Bart

Perhaps interesting to debate, that IF one chooses to only print at 360ppi (with no FinestDetail box checking), and if the native image for the given print size is above 360ppi, in these instances is it better to send 360ppi out of LR, or leave at the native resolution?   Ie. I assume in this instance that LR would do a better job of throwing away pixels than would the printer?   

for example, I suppose one could find themselves in a situation presented with eg. a 380ppi image and decide that uprezzing to 720 might not be worthwhile/noticeable benefit.   

[Bart_van_der_Wolf]

Perhaps interesting to debate, that IF one chooses to only print at 360ppi (with no FinestDetail box checking), and if the native image for the given print size is above 360ppi, in these instances is it better to send 360ppi out of LR, or leave at the native resolution?   Ie. I assume in this instance that LR would do a better job of throwing away pixels than would the printer?   

for example, I suppose one could find themselves in a situation presented with eg. a 380ppi image and decide that uprezzing to 720 might not be worthwhile/noticeable benefit.

Hi,

The short answer is that LR is almost certainly going to do a better job of down-sampling than a simpler resampling method as employed by the printer driver/pipeline. And it additionally allows to add sharpening after the resampling operation.

However, personally I would never throw away real resolution (the bit above 360 PPI). I see no reason, especially when upsampling to 720 PPI might even improve resolution of the data below 360 PPI (which would require special resampling software such as Photozoom Pro or Perfect Resize, that adds (edge) resolution that exceeds the native file resolution).

Cheers,
Bart

[JRSmit]

Perhaps interesting to debate, that IF one chooses to only print at 360ppi (with no FinestDetail box checking), and if the native image for the given print size is above 360ppi, in these instances is it better to send 360ppi out of LR, or leave at the native resolution?   Ie. I assume in this instance that LR would do a better job of throwing away pixels than would the printer?   

for example, I suppose one could find themselves in a situation presented with eg. a 380ppi image and decide that uprezzing to 720 might not be worthwhile/noticeable benefit.   

i suggest you test this for yourself. Just discussing 380 over 360 is pointless.
For me,  for my customers, i go for 720 and fine details on except if the ppi of the chosen printsize is lower than 360. How much lower is also based on the image quality as i perceive this. Note i print with epson4900 and epson9900, with Lightroom as my print application.  This is based on my experience and evaluations with my customers.

[Pic One]

Hi,

The short answer is that LR is almost certainly going to do a better job of down-sampling than a simpler resampling method as employed by the printer driver/pipeline. And it additionally allows to add sharpening after the resampling operation.

However, personally I would never throw away real resolution (the bit above 360 PPI). I see no reason, especially when upsampling to 720 PPI might even improve resolution of the data below 360 PPI (which would require special resampling software such as Photozoom Pro or Perfect Resize, that adds (edge) resolution that exceeds the native file resolution).

Cheers,
Bart

Theoretically, a 380ppi image upsampled to 720ppi, has 90%+ of pixels manufactured by lightroom, to then be sent with PR at 720ppi.  a 380ppi downsampled to 360ppi is removing pixels to print at 360ppi.   I wonder if there are instances/image types where the upsampling and higher resolution benefits could be outweighed by lower (360ppi) input/print resolution that has no software-interpolated pixels?

[Mark D Segal]

Theoretically, a 380ppi image upsampled to 720ppi, has 90%+ of pixels manufactured by lightroom, to then be sent with PR at 720ppi.  a 380ppi downsampled to 360ppi is removing pixels to print at 360ppi.   I wonder if there are instances/image types where the upsampling and higher resolution benefits could be outweighed by lower (360ppi) input/print resolution that has no software-interpolated pixels?

I think the only way to answer this question reliably on a case-specific basis is to try both and see which looks better. After trying a number such cases you may be able to develop a "general rule".

[Bart_van_der_Wolf]

Theoretically, a 380ppi image upsampled to 720ppi, has 90%+ of pixels manufactured by lightroom, to then be sent with PR at 720ppi.  a 380ppi downsampled to 360ppi is removing pixels to print at 360ppi.

Don't think that small amounts can do no damage. Even de-/in-creasing the image size by 1 pixel, will mean that 100% of the pixels will be recalculated/resampled. Depending on the quality of the resampling algorithm, that may reduce quality. It will probably not mean the end of the world for most subjects, but why reduce the quality to begin with?
Upsampling will also lead to recalculation of existing pixels, and the creation of additional new ones, but it may also lead to the possibility to use more sharpening at a smaller scale which will be beneficial for the perceived sharpness. If dedicated upsampling software is used you even (measurably) gain additional (edge) resolution, it adds quality.

I wonder if there are instances/image types where the upsampling and higher resolution benefits could be outweighed by lower (360ppi) input/print resolution that has no software-interpolated pixels?

An example I can think of is when the number of pixels in one dimension exceeds the quantity of pixels that the printer can print in the width of its feed mechanism. But that is a mechanical reason. Quality wise, more pixels usually means smoother gradients, (if needed with added fine dithering or noise) and the possibility of better sharpening.

The only possible quality benefit could be to create a very specific color that the printer driver can dither slightly more accurately with the number of ink droplets that fill a 360 PPI pixel, instead of a 720 PPI pixel, although a good printer driver will use error diffusion that utilizes 4 neighboring 720 PPI pixels to create the same overall color.

Of course fewer pixels means slightly faster printing, which would benefit 360 PPI printing a bit, but it remains to be seen where the bottleneck is (the slowest interface, probably reading from disk).

Cheers,
Bart

[dwswager]

I see this on this board over and over so I am just going to relay what Epson briefed a military program using their technology.  This is back a few years when the maximum resolution was 2880 x 1440, K3 inks and 3.5picoliter minimum droplet volumes. 

These were the relevant notes I took:

1. If you wish to preclude the printer driver from operating on your data prior to calculating the dithering pattern, the input image sample frequency should be an even multiple of 60ppi.  Hence 180ppi, 240pp, 300ppi...

2. Continuous tone printers that put down a consistent number of dots per linear inch across the entire printed area will re-sample the input data to the output frequency.  Epson Stylus printers do not operate that way.  There is no 1 to 1 correspondence.  It looks at chunks of 60x60 pixels of the input image and translates that to the image area to be covered by that chunk and based on the media selection and driver settings, calculates the dither pattern.

3. Epson Stylus printers do not have a native resolution as such.  The resolutions listed for the printer indicate the physical constrainst on how tight the droplet pattern.  A listed resolution of 1440dpi does not mean the printer WILL lay down 1440 dots per inch across the entire printed area, only that the algorithm is free to use up to 1440 different droplets per linear inch.   The goal is to achieve the appearance of continuous tone so the algorithm varies the location, volume and color of droplets as required based on the constraints provided.

4. The maximum pattern density is limited by the media type based on the ink load the media can take and the spread of the droplets. Plain paper, for example,  is both poor at holding ink and has a high drop spread.  Therefore, selecting that media type will preclude the printer using any of the higher resolution droplet patterns.

5. Apparent sharpness is obtained using the tightest droplet patterns on media with minimum droplet spread.  However, smooth, glossy media that exhibits the least dot spread also have a lower ink load limit than most heavy weight matte papers which exhibit higher droplet spreads.  The printer accounts for this by varying the number of drops and volume of each drop in calculating the pattern.

6. The best output is obtained by sending the printer the best image representation possible.   Do not expect upsampling of an image to result in superior output, unless that upsampling serves the purpose of actually improving the input data.  Specifically, once the input data sample frequency passes approximately 240 - 300ppi, any increase in sample frequency that does not involve an increase in actual quality of the input data is no longer productive.  The algorithm merely operates on the data given in conjunction within the constrains of the media selection to calculate the best droplet pattern.

7. Beyond 360ppi the media properties end up being the limiting factor.  For example, while Epson Exhibition Fiber has great droplet hold (low spread), it can't take the ink load necessary to take advantage of ever tighter patterns.  [I asked about smaller droplets and he conceded that that is the goal.  To tighten the pattern by using smaller droplets.  He still was not committal about any apparent improvements from the printing process being able to reproduce additional detail.]

I've been printing photos, on the Epson 3880, using the advice Michael and Jeff have advocated (that is if an image is below 360ppi, up sample to 360ppi, and if it is over 360 up sample to 720ppi).  

However, I've seen individuals advocate down sampling to achieve a larger print size...using Photoshop instead of Lightroom. In other words, taking a resolution down to 120ppi to achieve a 40 inch print for example. Is it best to always aim for 360 or 720ppi when Epson printers are concerned? Or is down sampling something to consider?

I'm doing an MFA in photography right now, and the individual suggesting down sampling is the head equipment tech (printers, etc.) I'm thinking he is wrong, but is he?

Thanks everyone!

JB Rasor

[Schewe]

I see this on this board over and over so I am just going to relay what Epson briefed a military program using their technology.  This is back a few years when the maximum resolution was 2880 x 1440, K3 inks and 3.5picoliter minimum droplet volumes. 

Sadly, this only perpetuates the myth. We know better now. It is better to send 360PPI than any other multiple of 60. That's the old myth. And yes, it IS better to upsample to 360 (or 720 using finest detail) than letting the driver deal with non-standard rez.

Sorry, but it's my experience the military doesn't always get the correct info about much of anything that doesn't actually shoot.

:~)