Retaining image quality

When producing artwork, especially for print, good image quality is vital to a high quality job.

A little bit of knowledge can be a dangerous thing. Especially when supplying images to your design agency. More and more people have Adobe Photoshop at their fingertips and unless you know the image size dialog box very well, you may be wasting your time making changes. If anything, you’ll probably be damaging the file.

When it comes to image quality, you can’t make something from nothing. If the image is small, making it bigger in Photoshop only increases the size of the file. Unless the image detail is there in the original image file, its quality won’t improve.

So how do we know the image size? If you have Photoshop, open the file, go to the ‘image’ menu and select ‘image size’. Uncheck ‘resample image’ and key in 300 pixels/inch in the resolution field. This will show you the maximum physical size the image can be when printed.

If ‘resample image’ is checked and you increase the resolution, you’ll be making the file bigger but the physical size remains. To make the resolution larger, Photoshop needs to create more pixels. Where do the pixels come from? It costructs them from the pixels around them. What does this do? It makes the image blurry!

Sometimes we’re supplied images taken from websites for use in print work. If an image is 150 x 200mm at 72 pixels/inch and we change this to 300 pixels/inch for use in print, the physical size changes to 36 x 48mm. That’s very small and probably not much use.

All computer monitors show colour differently unless, like our screens, they are colour calibrated for the monitor type and the ambient light of the room they’re in. If your monitor isn’t calibrated, you won’t see the image as it will be when it’s printed.

We prefer to be supplied images which haven’t been touched so that we know we have the best image possible. Please do check the size so you know what you have but don’t save any changes you make.