Working on a very large file - do I have to work in the full size?

[Natalie Creed]

I am working on a fairly detailed painted design for a rug, which is 230cm x 330cm. It's a tropical print with many elements, which I have painted individually and saved as .PNGs and am now composing. I was originally doing the composition in Illustrator but it kept failing to save, so I moved it to PS.

I am wondering if it's totally necessary to work in the exact full size, or if I could work on it at a quarter of the size and then stretch it later. Would the quality be very badly reduced,  or would it not be too visible? 

The file size is currently at a whopping 10 gigs, so it gies without saying that the process has been extremely tedious. 

This is my first time working in such a massive format, so excuse my naivety! 

Thanks in advance 🙂

[Derek Cross]

From an object that's to be viewed from a distance I would have thought a resolution of around 100PPI would be fine.

[D Fosse]

If you originally did this in Illustrator, you clearly have the skills and practice to make this as a vector file. I would strongly recommend that you try to resolve the problems in Illustrator and make that work. A vector file is resolution independent and can be scaled indefinitely. It is totally flexible.

With a raster file you need to decide a resolution. "Size", as a physical measurement, really has no meaning in Photoshop, not in itself. The size is determined by whatever ppi number you assign. The file itself is just pixels without any size.

It all comes down to intended viewing distance. The further away, the lower the ppi required at a certain size. At this size, you probably don't need more than around 70 ppi.

There is a limit to what the eye can resolve. You need to think in terms of degrees of arc in your total field of vision, not absolute ppi.

If this was a photograph, a rule of thumb is that a high-quality file from a decent, current camera will work for anything, magazine spread or billboard. Typically, such a camera produces 6000-8000 pixels long side. That may translate to 300 ppi for a small poster, but for a wall-sized banner the very same file may be printed at 20 ppi, and give the same optical resolution because it's seen from much farther away.

[JJMack]

The difference between 300PPI and 100PPI or 118.11PPCM and 39.37PPCM

‭1,058,783,040px vs ‭117,642,560px‬ is 9x Image size an 8 bit pixel is 3Bytes and 16bit pixels is 6Bytes.  You do not need a high resolution image for a rug.