Resolution is the rate at which the pixels are distributed on a monitor or print.
The rate is expressed as"
• Pixels per inch (ppi) for monitors.
• Dots per inch (dpi) for prints.
If there are lots of pixels per inch, the resolution is high.
Prints are often made with a high resolution, such as 300 ppi.
On such a print, the pixels are tiny.
There are many of them squeezed into every inch.
If there are few pixels per inch, the resolution is low.
A billboard may have a resolution of only six pixels per inch.
If you looked at the billboard from one foot away, you could see these enormous pixels.
But, because billboards are viewed from a distance, more pixels per inch are not needed.
A low resolution is sufficient.
Pixels can change their size.
The resolution, the ppi, "tells" the pixels how big to become.
Few Pixels Per Inch:
Lots of Pixels Per Inch:
The small version of the picnic table photograph below is small because the resolution (300 ppi) "told" it to be small.
The photograph's pixels are closely spaced: 300 ppi.
Similarly, the other version of the picnic table photograph is bigger because it's resolution (72 ppi) "told" it to be big.
The same pixels are now spaced out over a larger area: 72 ppi.
There are two common misconceptions about resolution.
The pixel dimensions of a file are not size dimensions.
They're geometric dimensions.
A JPEG file from a 6 megapixel camera typically has these pixel dimensions:
3008 pixels x 2000 pixels
It looks like the file has a physical size, but it doesn't.
3008 x 2000 is just a description of how the pixels are arranged—their geometric pattern—not their size.
The file needs a resolution to "tell" the pixels how big they should be.
We'll get to that.
People often think that pixels have a fixed size.
As mentioned, pixels can change their size.
We squish them when we use a ppi of 300.
We make them get bigger at a ppi of 72.
Pixels are very accommodating.
For the physical size of a photograph, you need the:
• Pixel dimensions, such as 3008 x 2000.
• Resolution, such as 300 ppi.
The resolution tells the pixels how big to become.
Let's look at another example.