Why Slipp-Nott requires vector files

File Types and Their Differences

There are basically two different types of graphics files: vector and bitmapped. The best file types for custom logos would be the native Adobe Illustrator file (.ai), a true vector encapsulated postscript file (.eps), windows metafile (wmf) or Freehand (.fh) file.

The easy, non-technical description of which file types to use:

Why Slipp-Nott insists on vector files

  • Vector files can be scaled up without any loss in edge detail.
  • Vector files will always print at the highest resolution of the printer.
  • Vector files can be easily edited, modified or recolored and matched as closely as possible.
  • Vector files use no compression.
  • Vector files are very small when compared to bitmapped files (usually between 30k to 200k).

Why bitmapped files are difficult to work with

  • Most bitmapped files are used for letterheads or business cards and therefore do not have enough information to allow us to scale the graphics to the printable size of our bases (15″ x 18″ for the SCS60 or 26″ x 26″ for the LSC60).
  • Bitmapped or raster files print only as sharp as their resolution. So even if you have a very expensive, high resolution printer, a low resolution image will print just as poorly as it would on a cheap inkjet or dot matrix printer.
  • If your files happen to be big enough for us to scale up and print at the appropriate size, they need to be multi-megabyte files (2+ MB).
  • Most bitmapped images use lossy compression schemes to reduce file size.
  • The nature of bitmapped images dictates that even apparently solid colors are made up of a combination of different colors do.
  • It is almost impossible to change any color without affecting the neighboring colors or to adjust the colors to match a specific color. Therefore, inevitably, customers send a file in that is a bitmapped image that was adjusted to print out properly on one particular printer but because of the nature of color printing, when it prints on another printer, it must be too dark, too red, too light, too yellow, too bluish and too something. Color matching an image such as this is almost impossible without a color profile. Color profiles are used by color management systems. Explaining what a color management system is and does is beyond the scope of “easy, non-technical description”.

A more technical description of what goes on with the different file formats

Vector files are the ideal file format for logos because they are resolution independent. In other words, vector files can be scaled to any size without any image degradation or loss of quality or detail. When you edit a vector file you edit a shape or geometrical characteristics based on mathematical formulae. Scaling a vector image up or down in essence changes the variables in a formula. The same vector file can be used for a business card and can also be scaled up to print a billboard on the side of a building!

Bitmapped files are Photoshop (.psd), Pict (short for picture), Graphic Interchange Format (.gif), tagged image file format (.tif), Joint Photographic Experts Group (.jpg), bitmap (.bmp) and Portable Network Graphics (.png). Photoshop, Fireworks, Paintshop and other paint programs generate bitmap images, also called raster images. These images are made up of a grid of small squares called pixels. Each pixel has a specific color value and location in the image. When you edit a bitmapped file, you edit individual pixels rather than shapes. Scaling a bitmapped graphic only changes the size of each pixel. Depending on the resolution of the output device and on the resolution of the bitmapped graphic determines how many “dots” are used to print out each pixel and ultimately how good a bitmapped image will look when printed.

For example, if the resolution of your graphic is 300 dpi (dots per inch), your printer is also a 300 dpi printer AND the image will be printed at its original size (no scaling) then each dot on the printer will correspond to each dot on the graphic. If you now double the size of the graphic, the final output size of the graphic will be twice the size in each direction (horizontal and vertical) but the resolution of the graphic stays the same. In other words, it is still a 300 dpi graphic, so in order to print it at twice the size, each dot has to be doubled in size in both the horizontal and vertical direction so now it will take 4 of your printer’s dots for each dot of your graphic. So as you go up in size on a fixed resolution file, the “blockier” and jagged the edges look and the more detail you appear to lose. In general, you can double, triple or sometimes quadruple the size of a bitmapped graphic before image degradation is noticeable. This is not a hard and fast rule, among other factors, things such as the nature of the image, the quality of the graphic and the software you use to scale it up will determine the output quality of the image.

Lossy vs. Lossless compression

While a simple concept and almost self-explanatory the issue of compression is quite sophisticated. Lossless compression reduces the file size of an image when it is closed but when opened for viewing or printing, it is displayed or printed at full quality. Lossy compression actually discards some information everytime the file is saved even if the file has not been changed. Using lossy compression means that your file begins to degrade from the first time it is saved. The level of compression (high or low) determines how much or how little is discarded and that is reason that a preview is presented prior to closing a file. Keep in mind that once that information has been discarded it can never be recovered. Depending on which compression technique and the level of compression used determines the quality of final image. VECTOR FILES USE NO COMPRESSION.

Specifying Colors and Color Management Systems

A color management is needed to “manage” colors of an image in order to reproduce the image as it was originally meant to be displayed or printed. Most of us see in color but our eyes like transistors, inks, monitors, electron guns, LCD panels, toners and papers while very similar are all different. Since one cannot control or predict how someone else will actually “see” a particular color, several companies have come up with a collection of colors and given them names along with specific combinations of colors/inks so as to create these colors. In order to enable these colors to be “matched” they create something known as color swatches and bind them into little books. These swatch books are then distributed/sold to the graphics industry so that people can refer to a specific color by name and be able to see them even though they are not in the same location. This method of specifying a color allows a relatively accurate method referencing of colors by phone, fax or through computer communications.
Color swatch books work well for people describing colors to each other but not for computers, cameras, scanners and printers. Those devices need something that allows all of them to know how each of these colors is going to be rendered. This something, is known as a color management system (CMS). A CMS uses things called ICC color profiles. ICC color profiles are based on specifications established by the International Color Consortium (ICC) and are generated by a color calibration system. The color calibration system generates a chart of known colors and these colors are output or read in the case of a scannerr or digital camera that needs to be “profiled”. These colors should be read back (if calibrating a printer) into the computer and analyzed by the color profile generating software so that it can generate a profile that indicates to the CMS the color spectrum should be handled by the various devices (digital camera, computer, printer, display or scanner) to properly represent the color.

The bottom line

While both vector files and bitmapped files require some form of color management, vector files are far easier to work with and generate a superior representation of your logo.