Could someone please tell me if it is possible to resize an image to about 2825mm by 1040mm but still maintain its clarity. It is to be printed on to vinyl and go on the side of a van the graphic people tell me they print at 75dpi its all getting a bit beyond me know. I understand that when you enlarge an image the pixels reduce thus bluring the image I think. Help.

What is the original size and dpi – that is very important… I can then help with advice.

There also used to be a programme that did a pretty good job of improving resolution for big enlargements, but I have no idea if it is still available – it is called 'Spline' – try a Google…

Cheers mastiles the original is 3008 pixels by 2000 pixels 17.21m taken from the box in photoshop when I click image size sorry I dont know where to find the DPI.

Image > Image size should give the DPI but it's craftily called "Resolution"

So what I need to know in order to calculate things is the original size in pixels with resolution (dpi) and the output size in pixels…

you only need that absolute figure of 3008 x 2000

at 75 dpi that gives you an image size of 40 x 26.6 inches (around 1000mm so way too small for your van side image – you will definitely see pixelation at 2.8m wide)

for the size of image you want for the van you'll need (very roughly!!) an image that is 8400 pixels wide at 75dpi

the interpolation programmes around can try and do this for you, but most are expensive – if it's a one off – you could ask a lab to do it for you, Genuine Fractals is also recommended.

So in answer to your original question my answer would be no – the image you have is not suitable for that purpose. I've seen plenty of vans about with low res images, and it just looks shoddy.

other options:

make your image just part of the display on the van and use text to make up the rest of the space

is your image a detailed photo like a portrait or landscape? if it is then your stuck, but if its more structural, you could convert it to a vector graphic, as that can be scaled up to any size (works best for logos, that kind of thing)

I have a book on Photoshop that explains how to do this. I have tried it on some fairly low res images & was impressed with how good it was.

I can check it this evening & write out the instructions for you if that's any good?
Or there's a basic guide to doing it here, which is the same thing:

http://photography-on-the.net/forum/showthread.php?t=25545

I think the important bits were to resample the image & make sure you select 'bicubic smoother'and if you want to make a huge enlargement do it in small steps, don't put in 200% straight away.

From the info you have given, 3008×2000 pixels at 75dpi (from the printers) will give you an image that is 40.1 x 26.67", which equates to 1018 x 677 mm. SO you will be pretty much doubling the size of your image to get it to the required size in your first post.

From the attempts I have made, I think it should still look OK.

You can interpolate in Photoshop. Give it a try and see what it comes out like.

gavinski is correct and his calculations sound. I am confusing my document size with my pixels and didn't really consider that pixel size is absolute.

Your image is about three times too small. Bear in mind though, people will be standing some way from a van side so the resolution may be adequate for your needs. Perhaps your printer could do a test strip?

Cheers for the help everyone I think I might try find an obliging vinyl sign company that may help in achiving the required quality. Don't suppose anyone can recommend anyone in Leeds.

Resolution is dots per inch.
Convert your final image size to inches 2825mm=111.2inches.

Then you can calculate how many pixels wide you final image needs to be:
111.2×75 = 8340

So you need to more than double the size of your original 3008pixel image.

That's a big resize, but you might get away with it. Some people would do it in once step and others will advocate doing it in smaller, incremental steps up to the final res.

Given the viewing distance that you'll need to be at to see the side of a van, you might get away with it. I'd get them to print a test sample (A3 size?) so you can evaluate in place, from the right distance, before you say "go" for the biggun.

What is the original image?

It's the inside of a Jiffy Catering Truck we want to put a vinyl on the outside of the door so when it is shut people can see what the vans carry as they look just like any old van otherwise. Just some marketing/advertising really.

They print at 75 dpi?

*shudders*

sturmey – a mate of mine Huddersfield way is in the business and happy to have a chat – let me know if its not too far away.
Chris