IS THIS IMAGE HIGH RESOLUTION?

That is a question I get a lot, and we have to take a little detour to answer it. There are two things that are important for the final size of an image.

PIXEL DIMENSION and RESOLUTION.

AN exAMPLE

We have an image that is 1000 x 600 pixels big. That is the PIXEL DIMENSION of the image.

Let's show it on two different screens, both with the same resolution, in other words1000 x 600 pixels.

One is a smartphone, the image becomes about 10 cm wide.
The other is a big TV. Then the images turns out 50 cm wide.

Same image – same PIXEL DIMENSION – totally different SIZES, due to different RESOLUTIONS.

Olika bildskärmar
RESOLUTION is measured in PPI – pixels per inch.

On the smartphone, you fit 254 pixels on 1 inch. On the TV you fit 51 pixels per inch. PPI = Pixels per Inch. (Often mixed up with DPI, which means dots per inch, not pixels.)

RESOLUTION IN PRINTING

In printing you use a standard of 300 ppi. That means the same image becomes 8,5 cm wide in 300 ppi.

This is how it looks in the menu Image size (under Image in Photoshop). Same image, same PIXEL DIMENSIONS, gives you different SIZES depending on the RESOLUTION.

Bildstorlekar

To change the resolution as the example above (with "Resample Image" unchecked) won't make any difference of the quality of the image. It is the same exact image (same PIXEL DIMENSIONS) regardless of RESOLUTION. Still 1000 x 600 pixels, in 51, 254 or 300 ppi RESOLUTION.

But in print you can use it at a maximum size of 8,5 x 5 cm.

Why it is possible to change the resolution if it doesn't make any difference? To make it easire when you mount the image in your design program, like InDesign. If all the images are saved at 300 ppi, you know you can't enlarge them, without losing quality – the pixels will start to show.)

SO IS MY IMAGE HIGH RESOLUTION?

YES and NO. All images can be "HIG RES". With high resolution you normally mean 300 ppi. The image above is high res, but can only be used at the max size of 8,5 x 5 cm in printing. If you need an image to be 40 c, wide, then it's Low res.

In other words – it's all about what size you need it to be.