Large Banner Printing

gibtheo

gibtheo

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Steven
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Hi guys,

I fear this may have been asked a lot so even pointing me to where I can find the information would be really appreciated, but...

I rarely print these days for commercial work, normally just send off the files as whatever type is requested jpeg, tiff etc. I have been asked to send a file for an image that would be OK to print for a pull down banner, approx 850mm x 2020mm.

I have tried to research this subject, but I have just got more confused. I have found out that there can be a few factors like print material, viewing distance etc, so, is there a definitive answer on what size a file should be to give a good print at this size when printed on banner material (plastic, smooth stuff) for a viewing distance of a few feet?

I'll be using a full size file from a 7D mk2 to make the print.

Thanks for any help in advance!
 
Your camera delivers images which have 5472 pixels in the long dimension. So to fit the banner you will need to crop to 5472 x 2303 and you will then have 2.7 pixels per mm or 69 PPI.

Is that enough? It's all you've got, so it'll have to be. But 69 PPI is the same resolution as a 32" HD TV. So it will be fine when viewed from a few feet away. Somebody with 20/20 vision will not be able to resolve the individual pixels from closer than about 1.4m away.
 
Don't forget most if not all printing software interpolates the data and can give really good large images from relatively small files. I have images from a 6Mpixel camera that have printed 30" x 20" with no problem. And yes they are sharp even close up. ( Decent lens helps ). I'd have a word with the banner printing company and see what they have to say. It can depend on the process they use as to how good the final image will be
 
It will be fine, I had one printed recently which was the same size but part of the banner used a photo that was only 1200px wide, I up-scaled it in PS and from about 2-3ft away it looks perfectly fine.
 
Hello Steven,
I work in the print industry for a company that does exactly what you're reffering to.
We generally receive files in TIFF & CMYK at approx 45mb.
These of course have been processed from the clients raw file which started out at anywhere between 16-24mb.
However, we have received simple jpegs of only a few mb's as low as 5mb & these have been printed out at 5 meters x 3 meters.
John is correct that most software interpolates an image.
Unless your image is of exceptionally poor quality it generally doesn't matter what file format or size you supply.
As a general rule TIFF saved in CMYK will give the best a printing company can hope for.

Should you want only an image then make sure what you want in the image has approx 10mm around it that you don't want.
This allows for trimming, unless of course you want a white border.
Quite a lot of banners have hemmed edges which are then eyeleted for installation purposes, ie. screws & washers or string.
These do need to have at least 10mm spare as the the hems are turned so as not to have a white edge, again unless you request this.
Hems are usually 25mm but the printer will add the 15mm of white.

The biggest mistake is to try & equate pixels to a finished size, remember that most computer monitors are HD @ 1920 x 1080 pixels as are most TV's.
My monitor is 61cm diagonal (24inch) which gives 53cm horizontal & 30cm vertical, this gives 36.22 pixels x 36 pixels = 1304 pixels per cm sq or 8412 PPI (pixels per inch)
However, my 46 inch TV which is also HD 1920 x 1080 has a horizontal of 40.5 inches by 22.75 inches vertical which equates to 2250 PPI.
The same HD amount of pixels but not the same PPI.
The pixels on the TV are bigger but are helped from the viewing distance & the fact that the image is moving & back lit.

With regards to your 7d MK II which has a sensor of 5472 x 3648 & correct me if I'm wrong 240 PPI raw files.
Putting into PhotoShop a blank background at that pixels dimension & at 240 PPi gives an image of 579.12 mm x 386.08 mm
Putting aside the final PPI resolution for a moment if you set the crop tool to the size you are after, 850 mm x 2020 mm you will lose approx 14.35 cm in height of the image assuming you use the full width .
Using the crop tool enter 2020 mm 850 mm & drag the tool from the top left to the other side & you will see the amount below that is lost, this is regardless of the PPI amount you put into the third box.
Try it with what ever resolution of PPI you like, the size of the crop will remain the same if dragged from top left to the other size as suggested.

I mention this as you may find you lose more of the image than you expect & so bearing this in mind you may need to consider this when taking a photo to be used for such & such size banner.
ie, put spare back/side ground around the actual subject if the final pint isn't going to be/use the full 3:2 ratio of the sensor you have.

The 7D MK II certainly has enough resolution to produce the required size banner.

Just to say that even massive banners still need a reasonable PPI of which I would say 69 PPI is the minimum.
Recently we printed a 45 meter long banner by 5 meters high which we received at 35 PPI & it was terrible, we up scaled the image to 150 PPI.
 
Wow! Thanks for all that info, that's really helpful. Another quick point then, would you recommend converting files to CMYK or leaving that to the printer to do?
 
Some printers don't use cmyk so it would be worth while asking them. Some printers only use sRGB because they can't create an icc profile for cmyk or adobe rgb. And simply use the printers default settings. So best ask always but the main thing is the crop factor.
 
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