Graphic Design Notes

My Notes in Graphic Design 2.17.2015

Notes   2.17.2015

Understanding File Formats

Understanding Format Choice and Image Compression

File Formats

   * All computer documents, or files, are packaged in different formats.

   * The format is determined often by the files origin, such as a software program like Photoshop, or device such as a digital camera.

   *  Graphic files such as a photo, video or artwork can be reduced in file size by using image compression formats.

Lossy vs Lossless

   * graphic image formats fall under 2 categories of compression, Lossy and Lossless.

   * With Lossy, image data is “lost” or reduced for smaller file sizes but can cause poor image quality. Can result in showing “compression artifacts.”

   * Lossless retains image data for higher quality, but larger file sizes.

[Don’t use JPEGs for flat graphics unless you like artifacts.]

Graphic Formats

   * TIF, JPG and GIF are the 3 most common formats for common activities such as printing, scanning and displaying images over the internet.

   * PNG is a common web format, is high quality and can contain an alpha (transparency) channel.

   * Each format has its own advantages, disadvantages.

[TIF is best for high resolution printing.]

File Format: TIF

   * Stands for Tagged Image Format.

   * Common format for desktop publishing, print, photo and graphic design.

   * Is a LOSSLESS file format. It retains image data for maximum image quality.

   * Can result in larger file sizes, not fit for display over internet, is not browser compatible.

File Format: JPG

   * Stands for joint Photographers Expert Group

   * Created for digital photography and works best for photo content

   * Is a LOSSY Format

   * Can reduce an image file size by 10:1 without showing significant compression artifacts.

   * The level of compression is adjustable.

File Format: GIF

   * Stands for Graphics Interchange Format.

   * Is best for graphics or images that have flat color or even tone, such as a cartoon.

   * Reduces image size by “indexing” color from 3 channels to 1.

   * Is adjustable by changing color bit levels from 1 to 8.

   * Contains no DPI (Dots Per Inch) data for printing. Not proper format for print.

Know Your Pixels

   * TIF and JPG are best for images with pixels that blend in color, these are called “contiguous pixels.”

   * GIF is best for images with flat even tone, or “non-contiguous pixels.”