Quality & File Formats


A photo may appear sharp and clear when viewed on a computer, phone or tablet, but when it is blown up to poster size it may lose its sharpness and become blurred or pixelated. This is because there is not enough information in the digital image file to fill a large space.

A digital image is made up of tiny points (or dots). You need these little points to be so small that when they are blown up to fill an A1 poster they are still quite small and will blend together without being noticeable to the eye. If they are not small enough then when they are blown up they become obvious and make the image appear blurry.

Basically - the more points the better and the more points the more information embedded in the photo and the more information the larger the file size.

If a photo is only 50Kb in size it will not have enough information embedded in it to fill an A1 poster size and so the points will become quite large. A 1Mb photo will have lots of information and tiny points which will remain small enough when blown up to be unnoticeable.

The photos below look the same at normal size, but are different files sizes. When the upper one, which is a larger file size, is blown up (as indicated in the circled area) the points are still small enough to be sharp to the eye. The lower one however is a smaller file size and the points become blurry when blown up.

You can check your photo will make a good poster by blowing it up on your screen if possible and seeing if it is still sharp and clear or by checking the file size (or both!) Anything below 500Kb will probably not make a sharp poster. Anything over 1Mb should be fine. File sizes in-between depend on the sharpness of the original photo.

Note - If your photo is not ideal to be blown up into a poster then you will be informed in the section where you upload your photo.


We prefer photos to be jpegs if possible. If not then tif, gif, png, eps and bmp files are generally fine also.