Pixel Resolution

People often use the terms Image Resolution and Pixel Resolution synonymously but there is a distinction.

Image Resolution is a way of quantifying how much detail has been captured in an image and is affected by such things as the resolving power of the lens and the quality of the image sensor. Image resolution is often expressed in lines or line pairs per millimetre.

Pixel Resolution on the other hand is a simple measure of the density of pixels in an image, usually expressed as a number of Pixels Per Inch (PPI) . Pixels Per Inch can confuse people because a 1 X 1 inch Image with a pixel resolution of 100 PPI actually contains a total of 10,000 pixels. 100 PPI really means 100 X 100 pixels per square inch..

The more pixels per square inch an image has the greater the potential for higher output quality.

Where more pixels means more quality.



These 4 little graphics are all the same size but they have different pixel resolutions. The first image is 100 Pixels Per Inch (PPI), the 2nd is 50 PPI, the 3rd from 25 PPI and the last one has a resolution of just 10 PPI.

An Ideal output resolution for printing

When printing, output resolution is expressed as the physical print size at a given pixel resolution.
For example: 20 x 40 inches at 300 PPI.

There is no single correct output resolution, and it depends to some extent upon the device you are outputting to. Not long ago 180 PPI was considered all you needed to sharply render a digital image in print. As technology has improved and printers have become capable of showing more and more detail, it's been established that some printers can resolve more detail than this.

For really high quality printing the ideal output resolution is now considered to be 300 PPI. At this level you can expect to get an excellent, faithful print (assuming your printer knows what they are doing).

At Finer Image, our printing process is capable of revealing yet more detail an we quote an ideal pixel resolution 360 PPI. This level of detail is beyond what the naked eye can see so we are talking razor sharp reproduction!

Up scaling Images

Having just read the last paragraph you may be tempted to scale all your images to 360 PPI. If you are downscaling to get to 360 PPI (i.e. you have pixels to spare), this would be a good strategy. On the other hand if you want to print big and you don't seem to have enough pixels to play with don't go crazy up scaling!

Having conducted extensive testing we recommend that if your image has less than 180 PPI resolution, it is worth carefully up scaling it to this point but not beyond. You will only succeed is increasing the amount of artifacts (noise) in your image beyond that point.

For images that don't contain a lot of fine detail you can get amazing results below 180 PPI.

Bigger Prints need less PPI

As the size of the print increases so does the comfortable viewing distance. For this reason you don't need as many Pixels Per Inch. A 40 X 30 inch print can look fantastic with a pixel resolution around 100 PPI.