Overview The emergence of the World Wide Web as a communication medium for individuals and institutions has created a demand for graphics that load quickly while rendering good visual quality to the viewing screen. Producing Web page graphics is a compromise between file size and image quality, and requires specific expertise on the part of the graphic designer. All bitmaps are constructed by assembling a rectangular grid or matrix of varying pixel color values to produce an image. For optimum results exporting from CorelDRAW 6 for MacIntosh , the .GIF and JPG formats offer high compression capability while reducing file size and maintaining image detail. Other options such as a transparent background, anti-aliasing, dithering, and interlacing change the appearance of the pixels in the bitmap grid, and must also be considered when selecting the appropriate file format. CompuServe (.GIF) The CompuServe .GIF file format should be selected when a transparent background is required to hide the rectangular bitmap grid found behind an irregular shape. From CorelDRAW 6 for MacIntosh, click File, Export, and click Compuserve Bitmap (GIF) from the format list box. Most Web page graphics are constructed by selecting the Custom page size with a setting of 150 by 150 pixels or less and selecting the industry standard resolution of 96 DPI. This resolution is the best trade-off between image quality and file size. Remember to select Identical Values in order to preserve the original proportions of the image. The GIF Options dialog box appears next. Use the Eyedropper tool to select the transparent color, and enable the Use Transparency and the Interlace Image check boxes. Example - Create a Transparent .GIF In CorelDRAW 6 for MacIntosh The following steps demonstrate the creation of a .GIF image with a transparent background. In this example, we will use a clipart image from the CLIPART folder on CD-ROM #3. 1. Import a clipart image into CorelDRAW 6 for MacIntosh. Refer to Fax on Demand document #3805 for more information. 2. Click File, Export, and click CompuServe Bitmap (GIF) from the Format list box. Click Desktop, and Selected Only. Type a filename, and click Export. 3. In the Bitmap Export dialog box, enable the Identical Values check box, and set the Resolution to 96 DPI. Set the Color Depth to 256 colors, and click OK. 4. Use the Eyedropper tool to click the transparent color, and enable the Use Transparency and the Interlace Format check boxes. Click OK. To preview the image, open or import the transparent GIF file into a web browser, or import the image back into CorelDRAW 6 for MacIntosh. Note: The transparent portion will remain visible in CorelDRAW 6 for MacIntosh. Joint Photographers Expert Group (JPG) File Format Select the .JPG file format if a grid-shaped matrix is appropriate for export and the image contains complex colors. The Bitmap Export dialog box offers color depths of 16 million colors (24-bit), and CMYK color (32-bit). Clicking the CMYK color depth will export the file with maximum image definition, however it will result in the largest file size. CMYK is useful for retaining color depth information when printing, however, it is of no value in an image intended for RGB monitor display. Click File, Export, and click .JPG Bitmaps (JPG) from the Format list box. Click Export, and the JPEG Export dialog box will appear. In the JPEG options dialog box you can adjust the image quality and the image pre-smoothing factor. The Image Quality slider bar allows an adjustment in the amount of compression being applied to the file. While it may be tempting to maximize the amount of compression to produce the smallest possible file size, remember that the lossy compression used with JPEG files will drop pixel information from the image when it is set to its maximum. Note: For best results, experiment with the setting to find the smallest file size possible while maintaining an acceptable compromise to final image quality. Image quality may be assessed by opening the image into any web browser. Text Tip Due to the nature of its compression, JPEG is not always a suitable file format to use for images that contain text; if the results are unsatisfactory with JPEG, use GIF instead. Glossary of Terms Interlacing is an option which speeds up the on-screen drawing when the image is opened in a web browser. This is achieved by re-drawing the entire image in incremental stages starting with a low-resolution thumbnail, and finishing with a high-resolution rendering of the image. The Dithered option converts or blends the pixel color values so that the graphic more closely resemble the original image. Use this option only if the image is losing detail, since dithering will increase the "pixilated" look of the graphic. It is applied to the entire image. Anti-aliasing blends or smooths the transition between two adjoining colors. It can improve the appearance of text, and create better definition on the edges of the visible area of a transparent bitmap.