Use the Quality command to select the amount of compression to be applied to an image. A higher Quality setting discards less data from the image, and preserves a higher level of image quality, but also results in a smaller reduction in file size. A lower Quality setting discards more data and further reduces image quality, but yields a smaller file size.

Compare several different Quality settings to find the right balance of file size and image quality. Begin by comparing the default Quality setting to the original image.

1	Click the 2-Up tab in the upper left corner of the document window.
	You use the 2-Up window to view the original image and the optimized image side by side. By default, the 2-Up window displays the optimized image with the current Optimize panel settings.
	Captions below the images display information such as optimization settings, file size, and estimated download time using a 28.8 kilobits per second modem. The estimated download time can help you determine if your image is small enough for viewers to download easily.
2	Compare the original and optimized images to find any degradation in quality caused by the compression process.
	In the example, the optimized image retains a high level of image quality, but indicates a 6-second download time. When the optimized image shows no visible degradation, you can try a lower Quality setting to achieve a smaller file size and faster download time.

3	Click the 4-Up tab in the upper left corner of the document window.
	You use the 4-Up window to compare view four versions of the image (the original and three optimized versions) side by side. By default, the 4-Up window three optimized versions all display the current Optimize panel settings. To compare different versions of the optimized image, select one version and choose new settings in the Optimize panel.
4	Click on one optimized image in the 4-Up window. In the Optimize panel, click the triangle next to the Quality setting and drag the slider to select a low quality level. For the purposes of comparison, choose a setting low enough to cause visible degradation in the image.
5	Repeat step 2 to apply another Quality setting to the third optimized image. Select a setting somewhere between the default setting and the low setting you chose in step 4.
6	Compare the file size, download time, and image quality of each optimized image. Try additional Quality settings as needed until you are satisfied with the balance of file size and image quality.
7	When you have determined the appropriate Quality setting, select the optimized image with that setting applied and click the Preview tab.
	While it is preferable to choose a Quality setting that preserves as much image quality as possible, a small amount of image degradation can be corrected using the Smoothing command. You'll learn to use the Smoothing in the next section of the tutorial.
	In the example, a 10% Quality setting (on the left) yields a significantly reduced file size (4.9K) and download time (1 second). However, the image quality also shows noticeable degradation, especially around sharp edges such as the windows and the text. A 40% Quality setting shows less reduction in file size (10.65K) and download time (3 seconds) but preserves acceptable image quality. The minor degradation around the sharp edges of the sign can be corrected with the Smoothing command.