Vector Graphics vs. Bitmap Graphics

Vector Graphics

Vector graphics are made up of lines and curves defined by mathematical objects called vectors.
Vectors describe an image according to its geometric characteristics. For example, a bicycle tire
in a vector graphic is made up of a mathematical definition of a circle drawn with a certain
radius, set at a specific location, and filled with a specific color. You can move, resize, or change
the color of the tire without losing the quality of the graphic.

Vector graphics are resolution-independent—that is, they can be scaled to any size and printed at
any resolution without losing detail or clarity. As a result, vector graphics are the best choice for
representing bold graphics that must retain crisp lines when scaled to various sizcs—for
example, logos.


Bitmap Graphics

Bitmap imagesfitechnically called raster images—use a grid of colors known as pixels to
represent images. Each pixel is assigned a specific location and color value. For example, a
bicycle tire in a bitmap image is made up ofa mosaic of pixels in that location. When working
with bitmap images, you edit pixels rather than objects or shapes.

Bitmap images are the most common electronic medium for continuous-tone images, such as
photographs or digital paintings, because they can represent subtle gradations of shades and
color. Bitmap images are resolution-dependent~that is, they contain a fixed number of pixels.
As a result, they can lose detail and appear jagged if they are scaled on-screen or if they are
printed at a lower resolution than they were created for.


Additional Notes:

Resolution

The number of pixels displayed per unit of printed length in an image, usually measured in pixels
per inch (ppi, often referred to as dpi). In Photoshop, image resolution and pixel dimensions are
interdependent. The amount of detail in an image depends on its pixel dimensions, while the
image resolution controls how much space the pixels are printed over. For example, you can
modify an image’s resolution without changing the actual pixel data in the image—all you
change is the printed size of the image. However, if you want to maintain the same output
dimensions, changing the image’s resolution requires a change in the total number of pixels.

When printed, an image with a high resolution contains more, and therefore smaller, pixels than
an image with a low resolution. For example, a l-by-l-inch image with a resolution of 72 ppi
contains a total of5 184 pixels (72 pixels wide x 72 pixels high = 5184). The same l-by-l-inch
image with a resolution of 300 ppi contains a total of 90,000 pixels. Higher-resolution images
usually reproduce more detail and subtler color transitions than lower-resolution images.
However, increasing the resolution of a low-resolution image only spreads the original pixel
information across a greater number of pixels; it rarely improves image quality.

Using too low a resolution for a printed image results in pixelation—output with large, coarse-
looking pixels. Using too high a resolution (pixels smaller than the output device can produce)
increases the file size and slows the printing of the image; furthermore, the device will be unable
to reproduce the extra detail provided by the higher resolution image.


CMYK

The CMYK model is based on the light-absorbing quality of ink printed on paper. As white light
strikes translucent inks, part of the spectrum is absorbed and part is reflected back to your eyes.

In theory, pure cyan (C), magenta (M), and yellow (Y) pigments should combine to absorb all
color and produce black. For this reason these colors are called subtractive colors. Because all
printing inks contain some impurities, these three inks actually produce a muddy brown and must
be combined with black (K) ink to produce a true black. (K is used instead of B to avoid
confusion with blue.) Combining these inks to reproduce color is called four-color process
printing. We recommend the CMYK model for all, full-color images.


Document Creation Guidelines

l. Document page dimensions should be the same as the publication’s final trim size.
2. Any element that is to extend to the trim edge of the publication should be extended l/8″ beyond trim for bleed.
3. No lines or anchored rules are thinner than .2 points.
4. All picture box frames have been specified correctly. If rule lines are for showing position only, indicate as FPO (for position only) on the laser to ensure that they will be deleted.
5. All images are positioned correctly in their picture boxes.
6. There are no gaps between images and borders or rules around the images.
7. You only have included fonts you intend to use, both screen and printer fonts. (Please do not send your completejont library.)
8. All unused colors should be deleted.
9. Colors should be defined correctly in color palette. (PMS colors as spot, process builds as process separation, CMYK.)
10. The pasteboards surrounding all pages should be empty. This will reduce the final size of the file.
11. When preparing a file, save as will reduce the file size. (This eliminates mini saves within the document.)
12. In Quark XPress only – grayscale / full color TlFFs are in picture boxes with a none fill.
13. No files have JPEG compression applied.
14. All RGB files are converted to CMYK or grayscale.
15. Perfect bound should be set up in the page layout program on single page spreads. Full bleed backgrounds and elements should be extended to bleed off all 4 sides by at least 1/ 8″.
16. All documents should be laser proofed for typographical errors and correct separation of all elements. (Both composite and color separated lasers are helpful.)

 

Design Jargon for beginners

CMYK

CMYK = Cyan, Magenta, Yellow, Black (K) — this is the four colors used in offset printing. Each color is traditionally printed on a separate color plate, with a different screen rotation. When layed or printed on top of each other it forms a dot pattern seen in printing. Think Lichtenstein prints where pictures are made up of dots. The dot pattern can be seen with a tool called a loupe.

The CMYK model is based on the light-absorbing quality of ink printed on paper. As white light strikes translucent inks, part of the spectrum is absorbed and part is reflected back to your eyes.

In theory, pure cyan (C), magenta (M), and yellow (Y) pigments should combine to absorb all color and produce black. For this reason these colors are called subtractive colors. Because all printing inks contain some impurities, these three inks actually produce a muddy brown and must
be combined with black (K) ink to produce a true black. (K is used instead of B to avoid confusion with blue.) Combining these inks to reproduce color is called four-color process printing. We recommend the CMYK model for all, full-color images.


RGB

RGB = Red Green Blue. Which is used in screen (web, presentations, LED light shows/projections or anything not printed on an offset printing press)

The RGB color model is an additive color model in which redgreen and blue light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three additive primary colors, red, green, and blue.

The main purpose of the RGB color model is for the sensing, representation and display of images in electronic systems, such as televisions and computers, though it has also been used in conventional photography. Before the electronic age, the RGB color model already had a solid theory behind it, based in human perception of colors.

RGB is a device-dependent color model: different devices detect or reproduce a given RGB value differently, since the color elements (such as phosphors or dyes) and their response to the individual R, G, and B levels vary from manufacturer to manufacturer, or even in the same device over time. Thus a RGB value does not define the same color across devices without some kind of color management.

Typical RGB input devices are color TV and video cameras, image scanners, and digital cameras. Typical RGB output devices are TV sets of various technologies (CRT, LCD, plasma, OLED, quantum dots, etc.), computer and mobile phone displays, video projectors, multicolor LED displays and large screens such as JumboTron. Color printers, on the other hand are not RGB devices, but subtractive color devices (typically CMYK color model).


SPOT Color

A spot color is custom mix of ink/color that is printed on it’s own color separation plate. It can also be a varnish or gloss plate.


More Jargon coming soon….

File Formats & Descriptions

EPS  (Vector File)

Encapsulated PostScript (EPS) language file format can contain both vector and bitmap
graphics and is supported by virtually all graphic, illustration, and page-layout programs. EPS
format is used to transfer PostScript-language artwork between applications. We recommend
EPS graphics for vector and bitmap images.


TIFF

Tagged-Image File Format (TIFF) is used to exchange files between applications and computer
platforms. TIFF is a flexible bitmap image format supported by virtually all paint, image-editing,
and page-layout applications. Also, virtually all desktop scanners can produce TIFF images. We
recommend TIFF graphics for bitmap images.


JPEG

Joint Photographic Experts Group (J PEG) format is commonly used to display photographs and
other continuous-tone images in hypertext markup language (HTML) documents over the World
Wide Web and other online services. JPEG format supports CMYK, RGB, and Grayscale color
modes, and does not support alpha channels. Unlike GIF format, JPEG retains all color
information in an RGB image but compresses file size by selectively discarding data. Due to the
fact the the JPEG format discards data, we do not recommend it for any images. If you must use
the JPEG format, please make sure all quality settings are at their maximum and the resolution is
at least 300 dpi.


BMP

BMP is a standard Windows image fonnat on DOS and Windows-compatible computers. BMP
format supports RGB, Indexed Color, Grayscale, and Bitmap color modes, and does not support
alpha channels. We DO NOT recommend the BMP format for any images.


PICT

PICT format is widely used among Mac OS graphics and page-layout applications as an
intermediary file format for transferring images between applications. PICT format supports
RGB images with a single alpha channel, and indexed-color, grayscale, and Bitmap-mode
images without alpha channels. PICT format is especially effective at compressing images with
large areas of solid color. This compression can be dramatic for alpha channels with their large
areas of white and black. We DO NOT recommend the PICT format for any images.


GIF

Graphics Interchange Format (GIF) is the file format commonly used to display indexed-
color graphics and images in hypertext markup language (HTML) documents over the World
Wide Web and other online services. GIF is an LZW-compressed format designed to minimize
file size and electronic transfer time. GIF format preserves transparency in indexed-color images;
however, it does not support alpha channels. We DO NOT recommend the GIF format for any printed images.