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Front Page » October 30, 2007 » Tech Tips » Learning graphic editing lingo, part 2
Published 2,529 days ago

Learning graphic editing lingo, part 2


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By JASON BAILEY
Sun Advocate/Progress


In the technical world, jargon is increasingly more important. With no understanding of the terms and definitions, users are left to blindly figure it out on their own. Graphic arts can be just as technical. Knowing some of these graphics-related terms can make the learning and exploration process a little easier:

Gamut

In simple terms, gamut defines the range of available display colors, which may vary depending on the context or scope. For example, a CRT computer monitor"s gamut will be different than the gamut of a printing press.

From a digital imagery perspective, gamut is defined primarily by the image mode used, which is generally RGB or CMYK. RGB gamut (red, green and blue) is based upon the mixtures of colored light, where CMYK gamut (cyan, magenta, yellow and black) is based upon the mixtures of inks. RGB is used in digital photography and in most digital graphics formats. CMYK is used primarily in commercial printing - like newspapers and magazines, for example.


Linear gradient

Radial gradient
Both basic types of gradients are shown above. Most graphics editing programs allow the user to mix more than two colors in a gradient.

Gradient

A gradient is a type of object (text, geometric shapes) fill that blends from one color to another. For example, the color may start at white, end at black and include incremental shades of gray in the middle.

There are two basic types of gradients: linear and radial. Linear gradients move in one direction, from left to right or top to bottom. Radial gradients, in contrast, are circular in nature and start from the center and move to the outer edge.

Many graphic editors that support gradients will allow gradients to include more than two colors and can often be used in text, backgrounds, geometric shapes and more.

Digital Noise

Generally undesirable, digital noise makes digital images appear "grainy" or "snowy." Often oddly-colored pixels scattered evenly throughout the image are to blame for the grainy appearance.

Digital noise is often caused by taking digital pictures with a high ISO (especially in excess of 1600) or in low light situations. It"s essentially the digital equivalent of film grain.

Many modern graphic editing programs have features that help remove digital noise. Although these features are helpful, they don"t usually eliminate the noise completely.


Aliased font

Anti-aliased font
A block of aliased text is aside a block of anti-aliased text (exaggerated). In most cases anti-aliased text is a benefit, but in some cases (especially with web graphics and transparency, anti-aliasing may not be desirable.

Anti-aliasing

Anti-aliasing, often called font smoothing, is a means of softening or blending edges of fonts to reduce harsh, jagged lines and make for a smoother appearance.

In programs like word processors, anti-aliasing is generally a really good thing, as it provides a smoother appearance which is easier on the eyes.

There are cases when anti-aliasing can actually be a bad thing, however. One case in particular is in web graphics, when transparency is important. Anti-aliasing, in this case, makes it difficult to clearly define opaque and non-opaque areas.

Moiré

Moire is a type of dot arrangement or pattern that commercial printing presses use to produce various colors and shading with a limited number of inks (cyan, magenta, yellow and black, for example). When printed materials (particularly newspapers and magazines) are scanned into digital form, the unique moire dot pattern is visible in the image.

Many scanners come with software that have a "de-screen" option. This helps reduce the moire effect as the scan is occurring. Many photo editors also have a moire pattern removal tool that can also assist with the removal of the dot pattern in the image.

DPI vs PPI

DPI stands for "dots per inch." PPI similarly stands for "pixels per inch." They sound very similar, which is why so many use the terms interchangeably. But the fact is that they are very different things.

DPI is most often used in the printing industry, where it is often used to describe the dots of ink on paper or other print media. Unlike PPI, it describes something that is tangible or physical.

Pixels, in contrast, exist only in digital form (inside a computer). Pixels do not have a physical size (in inches, centimeters, etc). PPI helps bridge that gap by identifying how many pixels should be allocated to each square inch. For example, a 150 PPI image means 22,500 pixels (150x150 or 150") are allocated to each square inch.

A higher PPI means the image will print smaller, but with higher clarity, because more pixels have been allocated to each square inch of the print. In effect, a higher PPI means there are more pixels to visually describe each square inch of the image. A lower PPI means the image will print larger but with poorer quality because fewer pixels have been allocated to each square inch of the print. Visual "pixelation" becomes a problem when printing images at really low PPI.

Many graphic editors are smart enough to calculate the proper PPI when printing, so the user doesn"t have to.

EXIF / IPTC

Unbeknownst to most people, digital cameras save a lot of very useful information inside the photo. Details like the date and time the photo was taken and settings used to take the photo (shutter, aperature, ISO speed, metering modes, etc) are all saved inside the photo. For a photographer, this is nice because the information from a successful photo shoot can be retrieved to replicate the same settings.

Most cameras save the data using the EXIF standard. Some cameras use IPTC. Even fewer use both.

Not all graphics editors read such data from the photo. On Windows, Adobe Photoshop (commercial) and IrfanView, a free (for non-commercial use) viewer are both capable of reading both IPTC and EXIF. On Linux, DigiKam, Gwenview and F-Spot all read EXIF. Other EXIF-compatible programs exist for both Windows and Linux (as well as Apple"s Mac OS-X). Check online for details.

Have comments about this article or suggestions for a future Tech Tips article? Send an e-mail to webmaster@sunad.com.


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