David Pahmp Photography

Is this a high resolution image?

I get questions about image resolution almost every week, and although it's fairly easy, it's a bit more tricky to explain. That's why I've rewritten this article a number of times. But here goes.

Is this image highres enough to print?

The correct but, not so helpful question is always YES.

But the question you really get back is "It depends on what size you want it.

For print, you need the resolution to be at least 300 ppi. So do this in Photoshop. Choose Image size under the menu Image.

Now uncheck "Change image resolution" and change the Resolution to 300 ppi.

Now this is about the maximum size you can print the image with perfect quality viewed from up close.

Pixel dimensions

First off, pixel dimensions. This one's simple – it is the image's width and height in pixels.

Pixel Dimensions

And if you want a shortcut, here's a quick guide.

Pixel dimensions for print sizes:

A5 – 1748 x 2480 pixels (300 ppi)

A4 – 2480 x 3508 pixels (300 ppi)

A3 – 3508 x 4961 pixels (300 ppi)

70x100 cm poster – 5512 x 7874 pixels (200 ppi)

7x10 m banner – 4134 x 5906 pixels (15 ppi)

So why does the ppi get smaller as the print gets bigger? Well, now we need to talk about resolution.

Resolution

Resolution is not too hard either really – it's the amount of pixels per inch (yes for resolution we use inches in this metric country too).

For a print that you view from up close, it's usually recommended to use a resolution of 300 ppi. That means, every inch contains 300 pixels. Pixels Per Inch.

300 ppi

If the image is very low resolution, like 20 ppi, it would look like this.

20 ppi

See? 20 pixels on that inch. 20 ppi.

For a giant banner that's printed and put on a wall, viewed from many meters away, you could get away with huuuge pixels. Like 1 pixel per inch.

1 ppi

Let's look at it like this.

From this distance all three images looks about the same size for the eye, although the difference is huge. If you use an image that is about 1000 pixels wide for all three, this would be the resolutions:

50 x 70 mm card : 1000 x 1408 pixels = 508 ppi (it's OK if it exceeds 300 ppi, it won't get any better or worse)

70 x 100 cm poster : 1000 x 1408 pixels = 36 ppi (now if you were to walk up to the poster, you would see the pixels though, so use the guide above)

5 x 7 m banner : 1000 x 1408 pixels = 5 ppi

So when is resolution important?

So if you're not going to print your image, you really don't have to care much about the resolution. Well, there is one other occasion, and it's on a screen. Your TV, computer monitor and your smartphone's screen all has different resolutions. That means they've managed to squeeze in a different amount of pixels in every inch. So showing a 600 pixel image at 100% on one screen may appear bigger or smaller, depending on your screen's resolution.

4 inch screen
1136 x 640 pixels
279 ppi

27 inch monitor
2560 x 1440 pixels
95 ppi

monitor

A4 (210 x 297 mm)
2480x3508 pixels
300 ppi

I hope it made some sense. If you're still stuck, please feel free to write and I'll try make it even better. Good luck with your pixels!