CMYK stands for cyan magenta yellow and blacK and is a color system used in the offset printing of full-color documents.
Offset uses cyan, magenta, yellow, and black inks and is often referred to as “four-color” printing. Monitors use red, green, and blue light instead, so they display images using a different color system called RGB. One of the great problems of the digital age has been matching colors between these two systems; i.e., taking a digital RGB image and making it look the same in print using CMYK. These problems are addressed by applications such as the Pantone Matching System.
To crop means to cut the pieces of an image that you don’t need.
Cropping differs from resizing because when you crop an image you retain the dimensions of the image. Resizing an image actually shrinks the image into smaller dimensions.
CSS, or cascading stylesheets, allow you to define how web page elements are displayed.
Specific margins or colors can be associated with elements on the web page; Headers and links, for example. When style sheets are applied to a new page, the elements are changed according to the specifications of the style.
To fill an image means to paint the inside of it with a selected color or pattern.
The fill can be used to create shading and other simple effects. In HTML, a popular technique is to fill tables with colors, especially in long lists of information. For example, if you are making a web page showing the 50 top-grossing movies of the year, it will be easier to read if you fill the rows of the table and alternate the background colors.
Flatten is a function in image-processing programs, such as Adobe Photoshop, to combine multiple layers into one file.
For example, in order to move the file to another program or save it as a GIF or JPEG, you will have to use the flatten function to combine all layers into one.