What is an image filter used for in web design?

In web design, an image filter is primarily used to modify the visual characteristics of an image by applying specific functions to its pixels. This process can include a variety of transformations such as blurring, brightness adjustments, contrast changes, or applying artistic effects. Filters allow designers to enhance images creatively and achieve the desired aesthetic without needing to alter the original image file directly.

The other options describe different aspects of image manipulation or editing. Cropping and resizing directly change the dimensions of the image but do not alter its pixel data in the same manner as filters do. Converting images into different formats pertains to file type changes rather than visual effects. Adding text over images is more about layout and design rather than directly modifying the image’s visual aspects through pixel manipulation. Thus, the choice relating to applying a function to an image’s pixels clearly defines the purpose of image filters in web design.