Be gentle with me - printing BIG

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#1
I have been asked by a friend to enlarge one of my shots to fill a large space on a wall. The pic (cropped) is 5462 wide by 3641 pixels high. She wants it printed to be at least 1m wide. I know that will be at a relatively low ppi. So I followed these steps:

I took the pic from Lr to Ps, resized to the required size (let's use 120cm by 80cm as an example) without any rescaling, giving me about 115ppi. When viewed on screen using the "print size" option the ruler along the top edge is correct against my tape measure so I figure this is what the print should look like and the quality looks perfectly acceptable. Once I go up to 150 by 100 @92ppi it starts to look slightly iffy.

Either way, this is much better than I expected so I wondered if I had done something wrong...?
 
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#2
I think it depends on your (and your viewer's) eyesight a lot of the time.

I have big prints that are at 90 odd ppi and they're absolutely perfectly acceptable. I did a 13x19 print from a 35mm negative scan (I think it was 2000px on the longest side) which was 105ppi and fine. Don't forget that at 1m wide, your viewer is probably going to want to be 3ft or more away just to appreciate the whole image, in which case their eyes can't physically resolve better than about 115ppi anyway. If this is an office wall and they're 6ft away they won't be able to resolve better than 50* :)

Nothing wrong I can see.

*based on a normal human with 20/20 vision
 
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Nod

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#4
IIRC there are some programmes that will upscale/interpolate better than others in a single step or you can upscale using PS or similar in several smaller steps. Again IIRC this reduces the potential for blockiness to set in and gives a more pleasing result than doing the whole upscale in one (PS) step.

Using a very quick calculation, she wants it (about) 40" wide. Using your pixel dimension of 5462pixels wide, printing the file with no interpolation will only reduce the resolution to about 136ppi which will probably be enough at a "normal" viewing distance for a print that large. If you can do prints at home, do an A4 print at 100ppi to see how good (or bad!) it looks at 1m+ which should give you a little wiggle room.
 
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#5
I would export from Lightroom at 300dpi and let the software do the up-scaling, selecting the sharpening choice based on the final material and the image style. I've printed up to 32" from a 20MP sensor in the past, and that worked very acceptably - camera and lens resolution become limiting before pixel density is a problem.
 

Asha

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#6
Can't say much more than what Ian and Nod have clearly explained tbh.

Without a doubt the viewing distance plays a huge part and as such 300dpi which my software screams alarm bells if it'sless for any given print that I'm about to make, may ( or may not) be ideal but not necessary unless your friend is going to scrutinise the print close up and pixel peep.
 
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#7
Dear dear me, how did we once print sharp A3 images from a 5-8mp file viewed at 2-3 foot?
Get it printed by someone who knows.
 
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#8
I find preserve details 2.0 in photoshop does the best job. There may be other specialist apps available for this, I doubt one off job warrants spending money on it.

It then all depends on viewing distance - the further the better; and and paper type. I would think about canvas or textured paper here. Smooth gloss is most likely to reveal lack of resolution first.

1.2x0.8m is not a big deal for a sharp file with over 5000px on long edge.
 
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#10
Your image contains ~ 20MP. A human with 20-20 vision physically cannot see more than ~ 14-15MP in any situation where the image is viewed as a whole (i.e. from a distance equivalent to the image diagonal). And the industry standard for "acceptable sharpness" requires less than 2MP.
 
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ianmarsh
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#11
From what I can see, the OP is attempting to obtain info so as to be "someone who knows" and then be able to do the print!

If you can offer him practical help then would that not be better than basically "send the file out to be printed" ?
Thank you. I'm using The Print Space in London who seem pretty professional but they leave the judgement of acceptable quality to the user. They suggested how I could test this, which is what I tried to do fro memory above. But thanks to the helpful comments it sounds like I'm on track. As mentioned above, large warning signs once I drop below 200ppi (on a website set up and used by people who know what they are doing) sow the seeds of doubt.
 
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#12
Thank you. I'm using The Print Space in London who seem pretty professional but they leave the judgement of acceptable quality to the user. They suggested how I could test this, which is what I tried to do fro memory above. But thanks to the helpful comments it sounds like I'm on track. As mentioned above, large warning signs once I drop below 200ppi (on a website set up and used by people who know what they are doing) sow the seeds of doubt.
While you *can* get acceptable prints at lower resolution, I can't see a downside to upscaling for output. AFAIK the better printers used to upscale client files before printing them, hence sending relatively low-res files off to a printer would result in large prints without obvious pixellation. As suggested, if your friend is going to only ever view the image for >1M away then there's no need for upscaling, but if you want it to look as good close-up where the whole of the image cannot be seen as at a distance then upscaling will help.
 
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#13
I've done a 48" print from the X-T2 by enlarging the image in PS using 300dpi. It was a shot of the Lake District and had it printed onto canvas. It's sitting on the wall in the lounge and looks fine from fairly close up too.
 
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#14
Thank you. I'm using The Print Space in London who seem pretty professional but they leave the judgement of acceptable quality to the user. They suggested how I could test this, which is what I tried to do fro memory above. But thanks to the helpful comments it sounds like I'm on track. As mentioned above, large warning signs once I drop below 200ppi (on a website set up and used by people who know what they are doing) sow the seeds of doubt.
From their website, this is what you should do:
Preparing your files for print
For beginners, you can prepare your files for print using the default colour profile Adobe RGB 1998. Our machines are calibrated daily with our own in-house colour profiles, so you’ll still get excellent results with the default profile. You’ll need to save your files off at 300 dpi at the desired print size (with any borders added).
https://www.theprintspace.co.uk/photo-art-printing-service/
 
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ianmarsh
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#18
Don't confuse things... the only thing you have any control over is ppi. Any reference to dpi is mixing terms erroneously.
That's what I though but as per their instructions above they ask for a dpi output. The video on their website is clearer and talks of ppi. But in any case I will go into their office Monday with the files and do it under their instruction
 
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#19
It does amaze me how many printing companies confue their customers by freely mixing the terms. It's no wonder people are confused.
 

Asha

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#20
Dictating a necessary DPI for any given print is like dictating a necessary weight for any given person.
There are many variables including, as far as a print goes, what IQ one wishes for or more impoprtantly requires depending on where, how and at what distance the print is to be viewed at ( Have we not basically already covered this?:thinking:)

Relating it for weight / person…..Depends on how slim / round that individual wishes ( or perhaps doesn't wish) to be.

There are no set rules, just guidelines, which CAN be ignored and not necessarily t the expense of a negative outcome!
 
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#21
Dictating a necessary DPI for any given print is like dictating a necessary weight for any given person...
DPI is the printer's resolution... dots of ink per inch. For a home printer it's typically a quality setting like "draft, normal, best, photo"; and for a lab printer it's whatever the printer is set for. There is nothing you can do with/to an image file that will change the DPI when a printer reads it. It also only relates to inkjet prints; and not actual photographic (silver halide) prints, which are made by a printer using RGB lasers or LEDs.

PPI is what we are concerned with. And it's pretty simple... how many pixels do you have, and how far do you want them spread out.
 

Asha

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#22
DPI is the printer's resolution... dots of ink per inch. For a home printer it's typically a quality setting like "draft, normal, best, photo"; and for a lab printer it's whatever the printer is set for. There is nothing you can do with/to an image file that will change the DPI when a printer reads it. It also only relates to inkjet prints; and not actual photographic (silver halide) prints, which are made by a printer using RGB lasers or LEDs.

PPI is what we are concerned with. And it's pretty simple... how many pixels do you have, and how far do you want them spread out.
Sorry I meant PPI not DPI……..but thanks nonetheless for the info.(y)
 
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ianmarsh
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#23
Thanks all for your help. In the end The client decided to go for 150 by 100 at 92ppi which was showing tiny deterioration in quality on my screen but she was happy. I used theprintspace and let Photoshop increase the psi to 300 at default as per their video instructions. I haven't seen the picture yet as it was delivered direct to the client but she is delighted which is all that matters.
 

Nod

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#24
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#28
Tell ThePrintSpace. They only accept files at 300ppi for the size of the pic you want.
Actually DO resize, because 300ppi is pretty much the standard for most printers, even though *some* will upscale for the customer from a lower res image. It's not a difficult thing to do, and although it creates large files, that's not a problem with modern internet speeds.

Glad it worked out in the end. :)
 
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