What I would like to focus on in this series of posts is why it is important to have a vector logo in the first place. Since you may be someone unfamiliar with the term "vector," I will begin by explaining the differences between vector and raster formats.
What is a Vector Format?
A vector format will not lose any image quality when it is enlarged. The edges will always be crisp and clear. It's like stretching a rubber band, it's always smooth even when it's stretched. Vectors are actually based on equations. So if you have say, a parabola, and know the equation for it, you can replicate that parabola at any size simply because you can determine all of the coordinates. Vectors work this way too.
What is a Raster Format?Something else that may be helpful to have explained in layman's terms is the concept of resolution. What do you really need to know about it to make sure your logo and imagery always look fantastic both on screen and in print?
A raster, or pixel-based, image format cannot be scaled up without losing quality. It is trying to stretch the same information over a larger area, but it tries to compensate for the lack of information by guessing what should be there. This causes blocky, jagged edges (sometimes called pixelation). It's like when you photocopy a small image that was drawn by hand and try to increase the size many times over. It doesn't take long before the edges begin to look rough.above: top logo exported from a vector format to 800 pixels wide, bottom logo stretched from a raster format up to 800 pixels wide (from an original 300 pixels wide). Click to enlarge, to more clearly see how the bottom one has become fuzzy.
What is Resolution?
Resolution refers to how much data there is within a specific area. This is usually measured in ppi (pixels per inch) for the screen and dpi (dots per inch) for print. For print that is sent through a half tone process, lpi (lines per inch) is also a factor, but dpi is more commonly discussed.
Screen resolution is generally assumed to be 72 ppi. This isn't completely accurate for all screens, however. The screen resolution is really calculated based on the pixel dimensions of the screen. For simplicity's sake, we will assume 72 ppi is generally accepted as appropriate for screen resolution.
High resolution for print is most commonly defined as 300 dpi (minimum). Since dpi and ppi are considered interchangeable, this means that for every 300 pixels of data, you can have one inch in print.
Obviously, there's a big difference between 72 and 300. Images that look big on the screen will most likely look smaller in print in order to preserve quality. Otherwise, something needs to change so that the item that appears on screen is a lower resolution and the item in print has a higher resolution.
If you click on the "Lady with a Fan" image above, the dimensions are 500 pixels by 707 pixels. At a resolution of 300 dpi (high resolution), this image would print at 1.67" x 2.36". At a resolution of 150 dpi, it would be printed at 3.3" x 4.7", but the quality would start to reduce. At a resolution of 72 dpi, it would print at 6.9" x 9.8", but the quality would be noticeably reduced (lines and edges become fuzzy).
Unless the image is exported at a larger size, or printed as a vector, it cannot be printed at high quality (300 dpi) at a very large size (e.g. poster size), as the quality would reduce too much. It is worth noting that posters and other large format items tend to use a lower resolution (often 150 dpi), but that assumes a greater viewing distance to offset the lower resolution.
Feel free to contact me with a low resolution version of your logo to receive an estimate on the time and cost it would require to vectorize your logo.
Come back tomorrow for part 2 in this series.
Next up: the difference between rasterized and vector text.