Copyright Goodheart-Willcox Co., Inc. 502 AutoCAD and Its Applications—Advanced Convincing, clear blue skies can be simulated using a gradient background. Initially, set the Top, Middle, and Bottom color values the same. Then, change the light- ness (luminance) in the True Color tab in the Select Color dialog box. Preview the background and make adjustments as needed. Using an Image as a Background An image can be used as a background. This technique can be used to produce realistic or imaginative settings for your models. If you select Image in the Type: drop- down list in the Background dialog box, a blank image is displayed in the Preview area. To locate the image fi le, pick the Browse… button to display a standard open dialog box. These image fi le types may be used for the background: TGA, BMP, PNG, JFIF (JPEG), TIFF, GIF, and PCX. Locate the image fi le and select Open. See Figure 18-22. Once the image fi le is selected, it must be adjusted. The Preview area of the Background dialog box shows the image with a preview of a drawing sheet. This drawing sheet indicates how the image is going to be positioned in the view. Pick the Adjust Image… button to open the Adjust Background Image dialog box. See Figure 18-23. Selected image file Image is selected Pick to adjust the image Pick to locate an image file Drawing sheet preview Figure 18-22. Setting an image as the background. Select how the sliders function Pick to select a position option Drag to adjust the image Figure 18-23. Adjusting the background image.