Digital Imaging Vocabulary

April update: Don't miss the "Extra credit" terms at the end, and the linked readings

After spending a few weeks with Photoshop, it's time to make sure you can "talk the talk" as well as working magic by pushing that mouse around.

So... Here we have a take-home test on the vocabulary of digital imaging, including Photoshop tool names, techniques and concepts. ALL of these can be found in our textbook, Deke McClelland's Photoshop CS5 One-on-One, the Photoshop Help system and Getting Started book (downloadable as a PDF too) or Adobe's Learn Photoshop tutorials. You also could search documents at Adobe.com or search of the Web in general, but watch out for non-Photoshop uses of the same words. (I hope no one tells me that a "sponge tool" is someone named Bob who lives in a pineapple.)

Some of these are tools and issues we haven't dealt with in class (especially those concerning Adobe Bridge), but they are useful concepts clearly explained in the One-on-One book.

Recommended preparation: Re-read (or read) Photoshop One-on-One's first six chapters (especially 2, 3 and 4). Do the "What did you learn?" exercise at the end of each chapter for a head start.

Also watch the accompanying videos. (Whatever you do, DON'T miss the Lesson 5 video! It's not a tutorial you have to do, but it's an entertaining video showing the real magic an expert can do with Photoshop. He does provide enough information for you to duplicate the effect -- even on a picture of yourself: You too could become a Smurf, or whatever they called those blue people in Avatar. Actually, Deke's not the only one with that idea.)

Back to the test: In one or two sentences that you understand, define the following terms; if the term is the name of a Photoshop tool, you should say what it's for, how it's different from similar tools, and what its icon looks like:

PSD file (how is it different from the other file formats?)
GIF file (how is it different from the other file formats?)
JPG or JPEG file (how is it different from the other file formats?)
Adobe Bridge
metadata
Batch Rename
Magic Lasso
Magic Wand
Rotate View Tool
Cropping Tool
Adjustments
Levels
Hue/Saturation
Burning
Dodging
Sponge Tool
Smudge Tool
Content-Aware Fill
Downsampling and Save-for-Web
Eyedropper Tool
Canvas
Polygonal Lasso
Saturation
Luminance
Eraser

Type up your answers in Microsoft Word, call the document "yourname-jargon.doc" and e-mail it to Dr. Bob by 5 p.m. March 18. (Original deadline was 5 p.m. on March 17... but a link was missing from the Web calendar during Spring Break.) One-letter-grade deduction for each 24 hours late.

Extra knowledge ("extra credit")...

These terms weren't on the take-home test when this page was originally posted, but they are SO good to know that I'll give you the definitions, with the terms linked to sources of more information. Like the definitions above, these may turn up on a follow-up quiz. Part of the reason is to clarify the difference between a "bitmap" and an "image map" so that the two similar terms don't confuse you on Assignment 6:

Bit depth --: The number of bits of information per pixel or per color channel -- such as the 8 bits per pixel of the red, green and blue channels of most of the images you see on the Web. (See the "bit depth" link above for discussion of 8-bits-per-channel versus 16- or 32-bpc.)
"BIT" is short for Binary-digIT. One binary digit can be either zero or one. Two binary digits can have zero or one in the "ones" place and zero or one in the "twos" place: 00, 01, 10, or 11 (or, in our usual base-ten numbers, 0, 1, 2, 3).
Eight binary digits can have zeroes or ones in the "ones," "twos," "fours," "eights," "sixteens," "thirty-twos," "sixty-fours" and "one-hundred-twenty-eight" places, which can add up to some big numbers for only eight digits. So what's 11111111 in binary? Reading left to right, those ones stand for 128+64+32+16+8+4+2+1...
Color Modes: RGB Color mixes red, green and blue to make colors, something like color spotlights on a wall. Each of the three eight-bit values in an RGB color ("24-bit") image can represent 256 shades. How many colors is that when you mix and match colors? 256*256*256 = ... more than 16 million! For comparison, each pixel of an 8-bit grayscale image can store 256 brightnesses from black to white, 0 to 255.
Bitmap (Raster) vs. Vector images: Photoshop primarily deals with bitmap images -- rectangular grids of pixels (picture elements). Vector graphics are used in other programs like Adobe Illustrator and Acrobat, which save lines and curves (vectors) as resizeable mathematical "objects."
Indexed Color: An 8-bit color image format used by GIF and other formats, not including JPG. Remember, 8 bits equal 256 colors, not the millions JPG can represent. Since indexed color does not show as many shades as RGB, it has to discard or approximate some.
Lossy Compression: The JPEG (JPG) image format also compresses the size of a bitmap image, but it is a "lossy" compression format that discards some image details.
Image Map (not to be confused with "bitmap"): A function the Web, implemented by Dreamweaver, that lets you combine a graphical image from Photoshop with a diagram of "hot spots" for Web page users to click on. Note: An "image map" does not have to be a geographical map, and does not have to be created with Photoshop's "slice" tool. See this floral example: Click on the top half of its flowery image, and one page opens; click on the bottom half, and another opens. Image maps also can be created in Adobe Flash graphics to present interactive sites like the Radford Art Walking Tour.