Resolution and Upscaling for Large Format Prints

Work out how big your file can print

Divide the pixels along each side by the pixels per inch you want, and you have the print size in inches:

• 24 megapixels (6,000 × 4,000 pixels): about 20 × 13 inches at 300 pixels per inch, 30 × 20 at 200 and 40 × 27 at 150.
• 45 megapixels (8,256 × 5,504 pixels): about 28 × 18 inches at 300, 41 × 28 at 200 and 55 × 37 at 150.
• 100 megapixels (11,648 × 8,736 pixels): about 39 × 29 inches at 300, 58 × 44 at 200 and 78 × 58 at 150.

Crop first, because a crop reduces the pixels you have to work with. Printers have their own native settings as well, so ask whether your lab wants files at a particular resolution.

What viewing distance changes

The further away someone stands, the less resolution they can see. Roughly 150 pixels per inch is about the limit of what a person can see at 2 feet, and that figure halves each time the distance doubles. That's why a billboard can print at so little.

A common rule of thumb puts normal viewing distance at 1.5 to 2 times the print's diagonal. Exhibitions are the exception, because people step in to look at the detail of a large print. Treat the rule as a minimum, and stay above it when the image has fine detail people will want to read up close.

When upscaling helps and when it hurts

Upscaling adds pixels, but it can only estimate what belongs in them. It's often fine for a moderate enlargement or a print seen from further back. These habits keep it safe:

• Finish retouching first, so the upscaling doesn't enlarge leftover flaws.
• Upscale from the master to the final size in one step, and sharpen afterward.
• Check skin, hair, foliage and fine edges at 100%. AI tools can invent texture that looks convincing until it's on a wall.
• Ask your lab whether it would rather upscale the file itself, so it isn't done twice.

With film, a new scan at higher resolution usually beats upscaling, and AI tools can turn grain into odd texture. Send the best scan you can get.

Noise, grain and banding

Enlarging shows what a smaller print hides: noise in the shadows, and banding in smooth areas such as skies and studio backdrops. Editing in 16-bit helps prevent banding, and a little fine noise can break it up where it appears. Film grain is part of the picture, so keep it even across the image rather than smoothing it away. A patch of missing grain can be as easy to spot at wall size as the dust it replaced.

Sharpen last, for the paper

Sharpen at final size, after upscaling, for the paper you're using. Matte and textured papers usually need more sharpening than glossy ones. Sharpening that's right for print often looks harsh on screen, so judge it on a test print. Ask whether your lab sharpens files too, so it doesn't happen twice.

Test at full size, and plan for big files

Before you commit to a large print, have the lab print the most critical section at its final size on the real paper. Soft proofing and test prints covers what to look for.

Files at this size get heavy. A 40 × 60 inch print at 200 pixels per inch is 8,000 × 12,000 pixels, or 96 megapixels, which comes to about 576 MB as a flattened, uncompressed 16-bit RGB TIFF. Ask your lab how it wants files delivered.

Getting a whole show ready is a bigger job, as preparing photographs for an exhibition shows. If you'd like help with the files, see exhibition print preparation.