Maximum Enlarging for Mural

[kuetj01]

I've searched for this specifically, and while I've found a lot of posts about enlarging, none quite apply to my situation.

I render 3d computer graphic images and am now getting requests to generate mural-sized images (10' x 16' to be printed at 150dpi or 28,800 px wide). Rendering the image at that size would take weeks, so I'm wondering what the smallest size is that I can render at, and then use the image resizing function in Photoshop to get it up to the final dimensions, without significantly losing image quality. For instance, can I start with a rendered image as small as 6000 px wide and gradually resize up to 28,800, or will the quality be crap? Has anyone had experience doing this? Appreciate any guidance/suggestions.

[davescm]

You will lose quality as you enlarge ​but.....

Start with the viewing distance.
The maximum resolution resolvable with good eyes is given by the formula ppi = 1/((distance in inches x .000291)/2)  - see link below.

So for example at 12 feet, good  eyes in optimal lighting, will resolve 1/((12 x 12 x .000291)/2) = 47 dpi.  At that resolution your 16 ft wide image would need 9024 pixels - anything else is wasted.

Unless you are decorating the inside of a lift, then typical viewing distance is 1.5 x diagonal - or in your example 18 feet.

That would give a resolvable dpi of 31 dpi, requiring 5952 pixels.

In short, at typical viewing distance - you should be fine with 6000 px to start.

The link below may help you.

Resolution for print viewing distance

Dave

[kuetj01]

Dave, thanks for your response.

The challenge is these are panels that are going to be used in a children's museum where the kids will be coming right up to the image. The client has stated that their print resolution is 150 dpi - so I'm assuming they've done the tests to determine what is appropriate for the spaces.

Of course they're located across the country from me and I don't have access to a large-format printer to test prior to sending them final files.

[davescm]

Can you render a couple of very small sample sections at the equivalent of say 6000px  then enlarge to 150 dpi and print yourself ( A4 or A3 ) and see what they look like close up ? That should tell you whether your starting point is acceptable at the viewing distance you envisage.

Dave

[kuetj01]

Thanks again.

Yes, I may end up doing that.

[postrophe]

Hi

The challenge is these are panels

Panels of 16' ? If it meant to be printed in 4/8 panels of 2' or 4', create files for each with some bleeds and registrations.

Faster done in InDesign and save as PDF.

Pierre

[Theresa J]

It's unlikely that they absolutely need 150ppi at actual size. I have designed a lot of wide format projects at half that resolution, and still got very good results. It depends a lot on the printer and the substrate. Trying a print test of your own is better than nothing, but it's too bad your client can't provide you some print samples. I think it's worth asking for clarification of the resolution. Ask to speak directly to someone who runs the prints and explain your situation the same as you explained it here.

[mytaxsite]

You can try:

File >> Automate >> Fit Image  (This is from the Menu bar, I am sure you understand this).

Then enter your new image size and then see if it works for you.