Does 'up-ressing' an image actually work?

Kell

Kell

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Kell
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Won't go into specifics as this is for a yet-to-be-announced work thing.

But we have an area to cover which is 3.5m by 6m. We've got an image we like from Getty - it's one of the biggest images I can find at 50MP and 9158 x 5459 pixels.

We've worked out this will be about 39 DPI if used as is - without extending it. Printers are recommending a minimum of 72DPI for this installation.

Would using one of those programmes actually give us the DPI to make it work?



Thanks for any advice.
 
My suggestion would be to crop an A4 (or even A3 considering the size) sized section of the larger print [with detail] printed at both resolutions - one at 39, and one upscaled to 72. Stick them on the wall and stand back to see if you can see the difference.

I read an article once about resolution and what the eye can see. 20/20 vision can resolve 72 at around 5 feet which feels about right. It will depend on your viewing distance though. If it's an atrium, high up and the viewing distance is further away (10ft+), I'd safely say 39 will be fine. If it's a coridoor/hallway with people able to get nose up close, you might want a higher rez. However, assuming this will be an expensive print, I'd do the tests either way. My up rezzing tests show that Lightroom and Photoshop do a pretty decent job, but I've never tested it with a print of that size. Most of mine have been up to A2 from old 8Mp files.
 
These programs can make images look clearer and do the job, if that's all you want. However, they can't produce data that was never recorded in the first place. Consequently, if you take a picture of (say) a book from such a distance that the text isn't readable, it looks sharper if you up-rez it - but that sharper result it still unreadable.

Obviously, if it's something pictorial, that doesn't matter - but there is always the risk of artefacts.

As Harlequin says above, do a small test and also make an 'enhanced' file and inspect it closely by zooming in, before you print anything.
 
Sounds like roughly the size of a 48 sheet billboard. I think the advice is 30dpi for one of those. but as Harlequin565 says, it depends how close the viewers are going to be.
 
Most of this echoes what I’m thinking. You cant just invent data.

Someone has suggested trying one of these programmes, but I’m more of the opinion that we might have to extend the image - or test print it and see if we live with the quality.

We’re trying to get some tests done but it’s a bit of an odd one. It’s an installation that parts of it you could be a foot or so away, and parts you wouldn’t be nearer than 20 feet. So to answer some of the questions above, the parts you're close to would/could/should look better than the parts you're further away from.

48 sheets look awful up close but they’re never designed to viewed that way.

As for other prints, I have a print of my daughter in our hallway that’s A2 taken on a 5MP camera. Unless you’re right against the glass you cant see the pixels.

So I’m not sure it will look horrible. But just wondered.
 
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Although no where near as big, I've had 3000px images printed out at A2 that have withstood close inspection.

When you translate that into roughly what you are chasing, I suspect that it'd be fine.


I can upres a 2000px file using Lightroom to 3500px with very little damage that will, again, stand up to inspection - as long as:
a) It's taken on a decent sensor
b) the image was decently shot (exposure etc)

However the gutshot quote of 72dpi from a printer would seriously worry me. Almost as much as one quoting 300dpi as if by rote.
 
I've had 7400px (on the long end) images blown up to more than 6m and they held up fine, I think the most drastic one I've done was 1500px on a big screen in Central London, but that was a dynamic display so you didn't have much time to scrutinise the image.

Adobe's Super Resolution works wonders as well, I've exhibited 50x40 inch prints with a 12,000px file that was created via it and they looked great up close, the source files were good quality scans of 5x4 negs.

The type of image is important too, if it's something with a lot of fine detail (feathers on a bird for example) then there are certain limits of acceptable-ness, but if it were something like the gradient of the sky without much detail then you could go nuts with the enlargement.

Generally speaking though, a 9000px file is more than enough.
 
I used to print very large images in my printing / framing business, my advise is to find someone who knows how to print these sizes with the approriate printer and RIP software for the printer they will be using, you will get a better print letting the RIP sort out the up sizing for the printer in use, it gives a far better print than doing the upsizing in an editing program, not all printers have the same natives resolution so upsizing to 36 or 72 may not suit the printer being used. RIP software is superb and very expensive and is used for one thing send the correct data to a specific printer.
 
mho said:
I used to print very large images in my printing / framing business, my advise is to find someone who knows how to print these sizes with the approriate printer and RIP software for the printer they will be using, you will get a better print letting the RIP sort out the up sizing for the printer in use, it gives a far better print than doing the upsizing in an editing program, not all printers have the same natives resolution so upsizing to 36 or 72 may not suit the printer being used. RIP software is superb and very expensive and is used for one thing send the correct data to a specific printer.
Click to expand...

Oh God yes. Always let the printer do the upscaling. It's what they are good at.
 
However they achieved it, it looked good in the flesh.

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We have a team of climbers who will be on it all day to highlight the vicious circle that homeless people find themselves in - and how the partnership can give give them help.

Image
 
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