Key terms and concepts

Adobe – software company established in 1982. Invented PostScript and later, the Portable document Format (PDF). They are responsible for the popular applications Photoshop, Illustrator and InDesign. Many beginners erroneously call Illustrator or Photoshop "Adobe" (as in "when I open up Adobe...") Don't make this mistake. Adobe is the company - use the name of the software you are working with.

Photoshop – raster image manipulation application created in 1986 by Thomas Knoll and purchased by Adobe in 1988 to be released in 1990. Version 8 (CS) was released in 2004. Version 9 (CS2) was released in 2005. This is the application you're chomping at the bit to master. Stick with these tutorials and you'll never need to buy another Photoshop book.

Raster Images – in contrast to vector artwork, raster images are made up of pixels and have a fixed resolution. Sometimes also called "pixel-based images".

Vector Artwork – (“structured artwork”) resolution-independent images / artwork defined by points in space (vertices) and connected by lines

Pixel – a single PICture ELement. The tiniest component of a raster image. Most pixels are square, though some are rectangular, depending on the display system. When you zoom in real close to your Photoshop document, you can see individual pixels. When you zoom out, you see the "big picture".

Resolution – the frequency of pixels within a given area of a document, typically one inch. A document with a resolution of 300 ppi will have 300 pixels per (linear) inch. Note the use of the word “linear”. Since pixels are square and documents are square or rectangular, the actual number of pixels in a given area is (the number of pixels across) x (the number of pixels down) (width x height). Thus a 1” x 2” document at 300 ppi will actually have 180,000 pixels in it (1 x 300 x 2 x 300). Doubling an image’s size will actually quadruple the number of pixels in it.

RGB – one of a number of ways of describing colour. This additive colour model describes a pixel’s colour in terms of a Red, Green and Blue component, usually in the range from 0-100% or 0-255. RGB gives you a palette of 16.7 million colours to choose from.

CMYK – a subtractive method of describing colour. Cyan, Magenta, Yellow and Black combine to create all the colours of the printable spectrum using standard offset lithography. CMYK images have a smaller dynamic range than RGB images, which means that less colours are available for the human eye to view.

Indexed Colour – sometimes, you can save a significant amount of disk space by representing image colours using a smaller palette. The common GIF file format used on the web is a good example of the use of indexed colour.

Image Size – we need to be careful when talking about an image’s “size” - are we referring to the physical width and height of the document or the # of pixels in the document or the file size of the document? The # pixels in the document is the most precise method of describing a document, but the large numbers tend to make this impractical.

Megapixel – 1 Million pixels. Approximately equal to 1150 x 850 pixels. Standard monitor resolutions are 640 x 480, 1024 x 768, 1280 x 960, 1600 x 1024. A standard 8 x 10 colour print at magazine print quality is about 2400 x 3000 pixels - 7.2 Megapixels.

PPI vs. LPI – lpi is a print measurement, referring to the number of printer dots per inch (not at all the same thing as pixels). A safe calculation for lpi is generally ppi / 2. Standard lpi values used in industry are: silkscreen (75 lpi), newsprint (133 lpi), brochure / magazine (150 lpi), art magazine (180 ppi).

Interpoation – the process by which new pixels are created or “invented”. When upsampling or resizing an image, you’re increasing the number of pixels in the document. Where do those pixels come from? The computer creates them Interpolation mathematically using a number of different algorithms. Choose the best algorithm for the job at hand.

-- Garmon Sutrix

Stay tuned for Tutorial 2: marquee selection methods and modifier hotkeys

thanks for those terms i knew hardly any of them will be referencing this page again lol

Hmm, I have to say that this is a very good compilation of terms and its definitions, etc etc. But I also have to ask - where did you get all this information? Or did you just paraphrase?

Anyway, thanks for this stuff. I think I'm sure there a ton more because these aren't the only terms that people need to know, right?

Maybe some slang or short terms used by users and stuff... just an idea

i've never knew 1/2 of them thanks!

nice terms, i didn't know 1/2 of them. thanks