
A pixel is a square of solid, flat color. Bitmapped art is made up of pixels and is resolution dependent.
You see it countless times in the
movies and on
television. Usually someone is analyzing security camera footage. “Can you zoom in on that?” “Can you enhance that?” Most of what we see is pure techno fiction, but it can be confusing to the average person. After all, we live in an age where technological leaps are happening all the time, why wouldn’t some of these things be feasible?
There are two basic types of digital art
PIXEL – A single, solid, square of digital color. Pixels make BITMAPPED art.
VECTOR – A mathematically defined path. Sometimes referred to as “line art.”
A pixel has no detail – only flat, solid color. Pixels makeup bitmapped art, such as photos, scans, or anything on the web or in video. Bitmapped art is resolution dependent. It requires the original image to have a high pixel count in order to show better detail.

A
vector, on the other hand, is resolution
independent. You can enlarge and reduce vectors all day without any loss of detail. Vectors can be given a fill color and a stroke color. Typical vector art includes logos, fonts, and flat-color illustrations created in Adobe Illustrator. However, vectors cannot give you the real-world imaging that bitmapped art can. (Sometimes people refer to vector art as “line art,” but not all line art is vector, as the term can also apply to hand-inked drawings.)
Let’s go back to our security camera footage. It is digital video, stored on a hard drive, and made up of pixels. The best security cameras on the market today only have a resolution of 811 x 508 pixels. That’s about a half of a megapixel. (Most cell phones take higher res pictures than that.)
On CSI, when they “enhance” the reflection in someone’s eye, the reality is there are likely only a dozen pixels in that part of the image (consider the eye in the top image). If I drew a dozen solid-color boxes and showed them to you, would you be able to see an image of another person? Of course not, because the information simply isn’t there. CSI is lying to you.
Can’t they just “zoom in?”
ZOOMING IN is something that a camera can do optically, but once the image is recorded, it’s pixel count is locked. “Can’t they just blow it up?” BLOWING UP is the common slang everyone uses to describe INTERPOLATION, a process in which software adds new pixels to an image by determining the most likely colors to exist between current pixels.
A bitmapped image can be “enhanced” in a variety of ways. You can manually repair it, but this is time-consuming, and you have to be a good image manipulator. This is the digital equivalent of taking your image to a car body shop. You can also use adjustment layers and sharpening.
Sharpening a bitmapped image will pull out details that are already there, but it can’t create detail. The sharpening process takes neighboring pixels and increases their contrast with each other. (This is a different process than increasing the Contrast on an image as a whole.)
Why does PRINT need images in such a high resolution?
In the design industry, we frequently run across this issue. A delightfully unknowing client may say, “Here’s some great pictures for that project. I pulled them off our website.” When asked if they can supply higher res pictures, they often wonder why we can’t just “blow it up.”
Unlike a website, which requires a relatively low pixel count, print requires 3 to 4 times the pixels for the same image at the same size because of a print process known as line screening. The higher the line screen, the better quality print you have.
Remember your old crumby laser printer from 15 years ago? It most likely had a line screen of around 60 lpi (lines-per-inch). A typical print press line-screen is 150 lpi. The way the science of printing works, you need two pixels for each line screen count. So a 150 lpi screen requires 300 ppi (pixels-per-inch). “Pixels-per-inch” is also called “dots-per-inch” or “dpi.”
“Blowing up” or interpolating a 72 ppi web image for print requires software to guess at filling in 3 pixels between each existing pixel. That’s a lot to interpret! Imagine driving down a road and only being able to see 1/4 of what is actually there. Or listening to a song in which only one of the beats from each measure is actually played. The software cannot add detail to what would have normally been there in real life – it can only fill in the blanks.
Used conservatively, interpolation can be successful in meeting print requirements without noticeably negative effects. Misused, however, interpolation will create unsightly digital details which you don’t want, instead of the real-world details which it cannot create. This is referred to as
pixilation. While it is true that there are software techniques that can improve interpolation, at its best, it can only reduce pixelation. It still cannot recreate real-life details.
How to recognize a bitmapped file vs. a vector file
Common file formats for pixel-based (bitmapped) art are: .psd, .tif, .jpg, .gif and .png.
Common file formats for vector-based art are: .ai, .eps and .pdf.
A .pdf can contain both vector and bitmapped art, but unlike pixel-based formats, a .pdf will retain the original vector information.
An .eps also can contain both vector and bitmapped art, but unlike a .pdf, not simultaneously. Although it was an essential file format even 10 years ago, the .eps is fading in its importance. You’re better off avoiding it.
Thanks!
I hope this gives you a better idea of how to talk to your designer and provide elements for your projects. It’s my hope that this will ultimately save you time, money and aggravation! Much success to you!