All posts tagged ‘Multimedia’

File Under: Glossary

Pixel


The cell is nature’s building block, and the pixel is the web designer’s. Pixel is one of those half-baked half-acronyms:PICture ELement. It refers to how monitors divide the display screen into thousands or millions of individual dots. A pixel is one of those dots. An 8-bit color monitor can display 256 pixels, while a 24-bit color monitor can display more than 16 million. If you design a web graphic on a 24-bit monitor, there’s an excellent chance that many of your 16 million pixels won’t be seen by visitors to your site. Since the agreed-upon lowest common denominator palette for the web has 216 colors, you should design your graphics using 8-bit color. (see Bit Depth)

File Under: Glossary

Bitmap

A bitmap is a mapped array of pixels that can be saved as a file.

Both JPEG and GIF are bitmap graphic formats. Currently, the only other way to store an image is as a vector graphic. You can’t easily scale bitmap images, but you can control every single pixel and thus achieve many effects impossible in vector graphics. Conversely, vector formats offer advantages of scalability and lower bandwidth requirements. When you compress a bitmapped image, you suck out some of the visual information.

To bypass this, the portable network graphics format (or PNG, pronounced “ping”) was designed to store a single bitmap image for transmittal over computer networks without losing this data.

File Under: Glossary

Bit Depth

Bit depth describes the file size of an image by orders of magnitude.

When wrangling with file size versus image quality, it’s often important to minimize the bit depth of an image while maximizing the number of colors. To calculate the maximum number of colors for an image of a particular bit depth, remember that the number of colors is equal to two to the power of what the bit depth is. For example, a GIF can support up to eight bits per pixel, and therefore can have as a many as 256 colors, since two to the power of eight equals 256.