Resolution for posters

[domdib]

A quick question. What resolution would people recommend if you want to get a decent print out on a 75 x 50 poster? The images in question could probably tolerate a little blurring, but I'd still like them to seem photographic.

P.S. - if you are in the UK, any recommendations on poster printing services?

Thanks!

[mt_sabao]

at least 150dpi. which means for 75cm which is more or less 30 inch you should have at least 4500x3000 pix. Ideally you should have the double, 300dpi, then in your case 9000x6000pix.

[mr-miley]

Yep, 300dpi would be your best bet. Bes of luck rendering an image at that size. Mind you, I have had some good results using one of the few image resizing apps (the ones that ONLY resize images) Something Lizard springs to mind. Blows up an image 5-600% with very little loss of quality. The software isn't too cheap, but it does 1 thing and it does it really well 

Miles

P.S. I'll have a rummage and see If I can't find the name of the software for you

PPS. http://www.imaging-resource.com/SOFT/GF/GF.HTM This is the one, though it looks like its not for sale by them anymore. If I come across any mor infor I'll let you know

[rcallicotte]

Miles,

Isn't this it? - http://www.ononesoftware.com/detail.php?prodLine_id=2

[Mohawk20]

I've done some 4096x3072 renders and printed them at 50x68, and they look really good! Not at all like enlarged or something, so you could probably print that same render size a bit bigger...

[domdib]

Thanks for all your replies. I don't think I've enough money in the budget for a dedicated resizing program, having blown it on TG2 Deep

I can probably stretch to 4800 x 3600 on the machine I have available, although that will involve doing three crops, as I don't have round-the-clock access. Somebody mentioned the possibility in another thread that this could lead to mismatches in GI, but I can't see why that would happen if the scene stays the same. Any thoughts?

Also, came across this company http://www.intelligence-direct.com/home/index.php, which seems a reasonable option for UK people.

[mr-miley]

Calico

Thats the bugger. I couldn't for the life of me remember who had bought the software! For anyone interested, I'd recommend this whole heartedly. It works really well and gives superb results.

Miles

[mhall]

A few thoughts ...

For the absolute, no holds barred in final output quality, rendering right to the required resolution is definitely best.

But, digital files have an amazing ability to be uprezzed to high quality large format prints. I've printed a 4MP ISO 800 digital still on outdoor vinyl at 5x7' feet and had people amazed that they could possibly come from a camera of that resolution. They were viewing the image from about 10 feet away.

Now I'm printing 10MP ISO 3200 and 6400 images in house at roughly 4x6 feet and they look better still - printed on an HP z3100 on some nice semi gloss paper stock.

The fact of the matter is that your viewing distance is a major factor in determining what resolution you will need in your final output.

If you are talking nose-to-the-print inspection of every detail then you will need the highest resolution possible. In photography, that's either really large format negatives and scanning or possibly photo mosaic of multiple digital shots to get extreme resolution. If you are talking looking at these images from a distance at which you will be able to take in the entire image at one time, then the required resolution drops dramatically (for example, billboards are generally a very low print resolution, but they can look really good when you are driving by on the highway, 50 or 100' away).

I've yet to see any digitally generated content that could live up to that sort of in your face resolution and scrutiny on a large scale - the level of detail needed in the image is incredible and usually falls apart on digitally generated content - mostly because of the time needed to create the detail by the artist.

You really won't need 9000x6000 sized files to produce some stunning output. That's 54MP ... Those 4000x3000 renders you did are approximately 12MP and - if the files are treated nicely - could produce some really great output up to some very large sizes.

One of the great things about Terragen (or any fully digitally generated output) is that you don't have to worry about digital signal noise, lens defects like chromatic abberation, lens flare, diffraction, etc., etc. like you have to in real photography. The output is extremely clean and can be upsampled beautifully.

So, don't think you HAVE to be able to render 9000x6000 to print those prints. And you don't have to have special software for the uprezzing. Bicubic interpolation works great on most images. That's available in most image editing packages out there.

Regards,
Micheal

[rcallicotte]

Thanks mhall.  This is helpful.  I like the idea of trying what Miles suggested...so I did a hunt and found about three different demos.   

[domdib]

Thanks for that very comprehensive answer Micheal - it's good to have input from a professional photographer (and nice site and some v nice photos by the way - my only small, font nerd reservation is Eras Medium for the titling, as it tends to look a bit broken at those sizes  ) I was thinking about increasing the size in Photoshop anyway, and the image really wants to be seen from about 3 feet away as it's a sweeping vista, so it sounds like 4800 x 3600 will be plenty.

[PG]

One thing though, how does image resolution (1680x1050 for example) equate to the quality they ask for (150dpi)?

[domdib]

I think the rough and ready answer is to equate pixels per inch (ppi) with dots per inch (dpi). So say you want a 30" by 20" image at 150 dpi. Well, that equates to a (30x150=)4500 x (20x150=)3000 pixel image. For 300 dpi, double it to 9000 x 6000 - that's what mt_sabao was suggesting. But mhall is basically saying that you probably don't need 300 dpi, especially if, as in my case, the image wants to be viewed from a distance anyway.

[PG]

OK I tried it at 9000x6000 because I'm pretty sure it crashes whenever I go over 7000x4667, it did indeed crash even though it was only using 1.7GB out of 8 but I found that switching on preallocate subdiv cache allows larger renders. So if you've been put off doing very large renders, as I have, by crashes then that's a way to get them done.

[mhall]

One possible method of seeing what resolution you need to get the quality you are after is to render cropped versions at different resolutions and then have them printed at a local lab or an online photofinisher. Send them 8x10 crops of the finished output and different resolutions and have them print them for you. Then view them from the relative distance you expect to view your posters.

That should give you some idea of what you will really need resolution-wise to get the quality you want. It will also let you see how the fine detail in your image is holding up and if you need to work on adding more or not. It may be time consuming to do this the first time, but the results will inform your later decisions about what size to render at and thus how long to tie up your machine on a particular project.

@calico - Glad I could contribute. I've been lurking for quite some time now and enjoying the images and insights to the software without being able to contribute much at all.

@domlib - thanks! I'll look into the use of the Eras Medium ... now that you've brought it to my attention, it's bugging me a bit as well. I want a decent sans-serif font for the titles, but definitely don't want Arial. Good, old school Helvetica may work, but something with a decent stroke weight would be nice for the titles.

[Oshyan]

75 x 50 - is that centimeters or inches? At larger sizes (above about 16x22 inches) you definitely don't need above 150DPI, and in fact most printers won't even print higher than that when printing to large size media.

- Oshyan