General Question on Print Resolution in LR

[Robert Boire]

Hello,

I want to prepare a fairly large image for a blurb book (approximately 20x8). However after cropping and exporting to pdf I find the resolution of the image is inadequate and the result grainy.

So my question is this. If I print out of LR and specify a resolution that is higher than what is available from the image for the selected print size what happens?  Does LR up sample the image? I yes, is the algorithm similar to what is available in Photoshop or CS? I ask because I was thinking of simply printing the image to a jpeg at a acceptable resolution and then reimporting it to the book module?

Thanks

[Tony Jay]

...If I print out of LR and specify a resolution that is higher than what is available from the image for the selected print size what happens?  Does LR up sample the image? If yes, is the algorithm similar to what is available in Photoshop or CS? I ask because I was thinking of simply printing the image to a jpeg at a acceptable resolution and then reimporting it to the book module?

Lightroom will upsample the image and the sharpening algorithm will apply appropriate sharpening for the upscaled image.
The upscaling algorithm is similar to PS but not identical in the sense, if memory serves, it dynamically changes how it upscales according to the degree required to give the best result rather than in PS where YOU have to know what algorithm works best.
Again, if memory serves, the most accessible reference to this, that I know of, is the CPS tutorial found on this website.

Tony Jay

[Robert Boire]

Thanks Tony. I do not remember seeing anything about this in CPS, but will check again.

After reading around a bit I understand that the upsampling will tend too reduce sharpness, which maybe defeats my purpose.

Also you wrote:

Lightroom will upsample the image and the sharpening algorithm will apply appropriate sharpening for the upscaled image.

Presumably this happens behind the scenes and I should deselect print sharpening to not overdue the effect?

R

[madmanchan]

In general I would recommend keeping print sharpening enabled.  Otherwise the results will likely be soft.

(Btw, are you preparing the Blurb books by using the Book Module in Lr or by exporting images separately?)

[Robert Boire]

In general I would recommend keeping print sharpening enabled.  Otherwise the results will likely be soft.

Actually I ran a test by printing to file and setting a resolution to 300, with and without sharpening. The native resolution for the selected print size is about 180. The sharpened result was significantly more crunchy.

(Btw, are you preparing the Blurb books by using the Book Module in Lr or by exporting images separately?)

I am using the Book module, but exporting to PDF to check my work before I upload the final versions.

BTW there are many enhancements that should be considered, most of which are not currently addressed in LR5 beta. I can provide a list if its not futile.

R

[Tony Jay]

Eric Chan is correct, he should be, since Lightroom is his baby.
It is possible to decide how vigorous the output sharpening is.
If you have a habit of being a bit heavy-handed with capture sharpening then output sharpening can be set to standard or low.
The opposite is also true.
Also don't forget to correctly set the paper type.

The issue of loss of sharpening due to upsampling is why Lightroom operates the way that it does.
The sharpening is appropriate for the degree of upsampling.
The process works - I have many prints where the native resolution was about 150 and I upsampled to 360 - the results were spectacular.

BTW the suggestion is upsample to 360 or 720 for Epson printers, and, 300 or 600 for HP and Canon.
Always upsample to the next highest resolution so, for me if native resolution is 370 I will upsample to 720, and NOT down to 360.
This is also covered in the CPS tutorial as well as in an article that Jeff Schewe wrote for Digital Photo Pro magazine.
I bet you this will also be well covered in Jeff's upcoming book - The Digital Print.

Tony Jay

[Robert Boire]

The process works - I have many prints where the native resolution was about 150 and I upsampled to 360 - the results were spectacular.

Hmmm... I tried several cases and in each case the output sharpening made the upsampled image considerably worse. I even tried removing all develop sharpening (under the theory that I was oversharpening) and max output sharpening..with the same result.

Then I tried my original develop sharpening, max output resolution, output resolution of 360 as you suggested for my Epson  (I had been using 300) ...with the same results.

Then I removed all develop sharpening in case I was being "heavy-handed", selected max output sharpening and output resolution of 360 as you suggested for my Epson...voila the best result of all ! Even better than my original image before upsampling.  Thanks I had forgotten that detail.

 BTW I am not sure  how meaningful or reliable this the comparison process is. When I compare the sharpening I print to file (not a real printer), import the file and then reexport to pdf via the book module.

Which raises another question about the book module for Eric. When I print out of the print module, LR upsamples and sharpens as appropriate for my selected print size and image resolution. What happens when I export to pdf via the book module?  Does any sampling happen if the resolution for the selected page size is inadequate? It does not look like it.


R

[Schewe]

BTW I am not sure  how meaningful or reliable this the comparison process is. When I compare the sharpening I print to file (not a real printer), import the file and then reexport to pdf via the book module.

Exactly how are you looking at the results? In Photoshop? What zoom? The problem with on display sharpening is you can't really do it. A computer display is prolly about 90-110 PPI. You print output is prolly 300 PPI. So, how do you look at high rez images on a low resolution device? With great difficulty...

If you look at your image at 100% in Photoshop, you are looking at an image that is about 3x the final printed size. So, ok, you decide to look at the image at 33% (about 1/3 of the print rez). The problem there is a down sampled screen display sucks because, well you are looking at the image about real size but showing only 1/3 of the resolution...

You you only real choice is to do actual printed tests...that's really the only way to examine and evaluate the output sharpening for the print. Which is what Bruce Fraser did when he designed PhotoKit Sharpener.

[Tony Jay]

Yes, Jeff has put his finger on an important point.
Sharpening, and it effects can only be compared in the final output form.
If you are sharpening for monitor output, good and well, use the monitor as the arbitrator.
If you are sharpening for print then only comparing prints is useful.
It is always a feedback process although after a while it becomes possible to make very educated guesses as to how a monitor view of an image will translate into print.

Tony Jay

[Robert Boire]

Thanks both.

Sharpening, and it effects can only be compared in the final output form.
Tony Jay

and

Exactly how are you looking at the results? In Photoshop? What zoom? The problem with on display sharpening is you can't really do it. A computer display is prolly about 90-110 PPI. You print output is prolly 300 PPI. So, how do you look at high rez images on a low resolution device? With great difficulty...

Hmm... good point.

Again, this is what I  was doing for the upscaled images. I print to file,reimport and then generate a PDF in the book module to examine the results. I am looking at the PDF generated by the Book Module in Adobe Reader zoomed to the approximately the real size of the page format that I selected for eventual printing by blurb. I am in effect trying to "Print Preview" what will come out of their HP printers.  This makes me think that even for the images that I do not need to upscale (ie do not print and reimport into the book) I do not have a reliable method of previewing the sharpening.

So I guess what you are saying is that the only reliable thing I can do as far as sharpening and blurb is to print some sample prints on my own printer as a sanity check.

Any thoughts on my other question from the last post:

Which raises another question about the book module for Eric. When I print out of the print module, LR upsamples and sharpens as appropriate for my selected print size and image resolution. What happens when I export to pdf via the book module?  Does any sampling happen if the resolution for the selected page size is inadequate? It does not look like it.

For that matter what happens when I export to blurb? Is there any behind the scenes upscaling or sharpening? Presumably not.

Thanks

R

[jrsforums]

For that matter what happens when I export to blurb? Is there any behind the scenes upscaling or sharpening? Presumably not.

Robert, this last is probably the most important.

While you have been given info on viewing on screen vs. actual test prints, I am not sure it directly helps you with Blurb.

Testing on a printer will not, most likely, give you any feeling for what output to get from Blurb.

I have not worked with Blurb...directly or via LR.  However, in LR, I see no controls for sharpening....and even if you had them, you would still need to get output from Blurbs process to see the results.

It is not clear to me if resizing (up or down) is done in LR before sending to Blurb or is the image, with crop info, is sent to Blurb, with the rest of the layout....and then done there.

It seems like a "black box".  Now I do not mind "black boxes" for output....LR resize/sharpening is one, as is Qimage's.  However, both have a local (or lab) print which you can view to test/retest until you get it set up for consistent results. 

Unfortunately, one does not have that with Blurb.  Nor do I see any "levers" which you would have to modify output if you were able to preview (in print) the Blurb output.

John

[Robert Boire]

It is not clear to me if resizing (up or down) is done in LR before sending to Blurb or is the image, with crop info, is sent to Blurb, with the rest of the layout....and then done there.

Precisely. That and a few other things are far from clear. I would have expected details about what goes on (if anything) in the black box to be covered in the documentation... Alas

Robert