High resolution images for large posters in Photoshop

For anyone reading this in 2025 or later: Use AI. period.

use an upscaler (my prefered one is Upscayl) to not only largen the image but also add more details.

Hi

Is your file really that small? 72ppi and 1000 pixels across? At the printers ideal file-size of 300ppi that would print just under 8.5 cm across.

Note that a large printed image generally needs no more pixels than a magazine full page. That's because a large poster is viewed from a greater distance. So A4 (21x 29.7 cm) / 300ppi is a good point to start. 21x 29.7 cm at 300ppi would mean a file of 2480 x 3508 pixels. [ just over 8 megapixels ].

I have a client who has smallish digital files and makes art prints up to 375cm wide which can be viewed pretty close, that’s what he wanted, because that’s what people may do in art galleries  - they use a step by step upsampling with judicial sharpening [and maybe occasional blur I think] during those steps. Its hard to do, time consuming  and laborious - and as he's developed his method over many months, I don't imagine he's interested in divulging it. So there are perhaps possibilities, but, sorry, I can't tell you how exactly how he does it.

I doubt your poster printer would be happy anyway, the images I mention above are a special case really as they are abstract with lots of movement blur.

Really shooting at 72 ppi for print is crazy, you may need to look at your camera settings to get a more reasonable file size.

Even an iPhone 7 can make a file 4032x3024 pixels (12MP).

I hope this helps

thanks

neil barstow, colourmanagement

Hi

Are you taking your own photos? If yes, give us the camera details. Maybe your settings need to be adjusted.

Or are you purchasing the photos from Adobe Stock or another vendor that sells photos? They will have the pixel detail listed before you purchase. Be sure to read the usage terms.

~ Jane

VipGirls  wrote The images I am currently working with are around 1000 px plus and 72 dpi initially (before increasing to 300 dpi).

Forget the dpi  It's pixels that count, and 1000 is barely enough for a 6x4 print, yet alone a mid sized poster.

If you can't find a higher resolution version of the image you are working with, use a different picture.  Don't consider upsizing an image to reach the desired pixel size. The original size out of the camera is what counts.  Try to get at least 4000 pixels on the long side.

You can't make a silk purse out of a sow's ear.   Hi-res posters begin with high quality, high  resolution images.  If all you have are low quality images, don't enlarge them.  Keep them the size they are now.

As everyone wrote Increaseing the image size will degrade your image quality.  You need to start with a high quality image from the beginning like  a well exposed well focus image from 16MP+ digital camera.  You need to have a lot of high quality pixels for your Portrait Poster size image.

Incremental upsampling is a myth. It only introduces additional artifacts.

Upsampling is usually not necessary if the original is of good quality and a reasonable pixel size. Any good file from a current mid-to-high range camera will work. Upsampling will never improve an image, but it will disturb the pixel structure and potentially make it look a lot worse than the original.

You don't need higher resolution for larger print size. You will see it from a greater distance, so the optical resolution stays the same. It will still occupy the same angle of view in your eye.

I'd go with Dereks' recommendation and upwards. More pixels never hurt, but you reach a point where it's wasted. 150ppi should be perfectly fine at this size.

To produce a poster of a size of 40cm x 60cm  you need an original image that's at least 2400px x 3600px

So you have to start with a good enough original. You can't just take something off the web and decide to print it the size of a house.

Hi. You need to start with a high-resolution image if you want to print in high-resolution. If you start with a low-resolution image, that image doesn't have enough information about image details. The filters or commands for upscale duplicate pixels but doesn't create details.

The exact resolution that you need for your images depends of the printing system, quality, etc. The printer can tell you what resolution to use.