Print Resolution with DigitalCreative.info's Guide to Digital Photography and Image Manipulation

We've saved our image files from the camera into a folder ....... let's have a look at what we'll find. Open Adobe Elements, go to File / open and browse to the folder of choice to find your image; highlight it and click, 'open'.

1. Your picture opens in the window ready for you to start work. Let's take a few minutes, though, to consider what we've actually been presented with. The blue bar at the top of the image tells us the title of the file, where it's located and its size, relative to the number of pixels contained in the file. This image is showing at 45.25%.

2. If you go to View/actual pixels, it will display at 100%, as shown below. It won't all fit on the screen but it shows the actual pixels and you have a better idea of how well it will print:

3. If we look at the image size dialogue box we'll see that along the width of the image there are 1728 pixels and the height has 1242 pixels. If we print this at 240 ppi (which will deliver a good quality print on a decent printer) it will produce a print of 18.29cms by 13.34 cms. in size. If you need to print at 300 ppi, (the resolution usually required when sending files for publication in magazines) then the physical dimensions of the print will be correspondingly smaller.

4. If we were prepared to print it at a lower print resolution we would see that at 100 pixels per inch we would get a picture 43.89cms wide by 31.55 cms high. Notice that the number of pixels hasn't altered - we would be stretching the same ones out and making them larger, and more obvious, in order to produce the larger print. Visual quality would be reduced drastically .

5. Taken to a logical conclusion you'd get a print on which you could identify every pixel so that it looked like a mosaic. If you only start off with a relatively small number of pixels this stage will be reached quite quickly!

6. If you find yourself with too few pixels to print at the size you need then you have the option to add more pixels. Go to Image/image size and you'll see the following dialogue box. Check 'resample image' and make sure that 'bicubic' and 'constrain proportions' are selected. Select the width or height and enter the size that you require. You'll notice that the number of pixels will increase, as will the file size. This is a process known as 'interpolation' in which Elements looks at the colour information in the existing pixels and creates more to match in order to allow a larger print to be made. This works very well in some images but, in images where sharp detail is necessary, the result is not always as satisfactory or acceptable.

You can work on the following sizes as a guide to the file size you need to be capturing, in your camera, at the picture taking stage:

1. To produce a print approximately A5 in size, ie within 21cms by 15cms:

At 300 ppi you will need 2480 pixels by 1754 pixels.

At 240 ppi you will need 1984 pixels by 1403 pixels

2. To produce a print approximately A4 size, ie within 29.7cms by 21 cms:

At 300 ppi you will need 3508 pixels by 2480 pixels. this is the size most magazines will ask for if work is to be published.

At 240 ppi, using a printer designed for photographic quality output, you will need 2806 pixels by 1984 pixels.