JPEG

Choose GIF instead of JPEG for flat tone images such as logos and cartoons.

1 open grayscale or RGB image in Photoshop

Open the image in Photoshop. Go to Image > Mode and in the drop-down menu select Grayscale (for B&W images) or RGB (for color images).

2 size to 72 pixels/inch

Size the image to a resolution of 72 pixels per inch. If the image is already at 72 pixels per inch, do not resize. If it is a higher resolution, resize to 72 pixels per inch.

To size the image (reduce the resolution), go to Image > Image Size. Note the original pixel dimension of the image (216 in this case). Specifying a pixel dimension larger than the original results in distortion. At the bottom of the dialog box, type 72 in the space for resolution. You may need to specify the width or height of your image. Make sure you select pixels as the unit of measure in the drop-down menu. For an image that looks 3 inches across on your web page, type in 216 in the space for width. (If the original image size is smaller than 3 inches, rescan the image at a higher resolution in order to enlarge it to 216 pixels - 3 inches - for the web page). Note the two check boxes at the bottom of the dialog box. Both should be checked. Click OK.

3 save as JPEG (.jpg)

Go to File > Save As... Name your file and give it the .jpg or .jpeg extension. Choose JPEG from the drop-down Format menu. Click Save.

A JPEG Options dialog box appears. (see image below) This allows you to specify the image quality. Usually Medium is a good compromise between filesize and visual quality. Experiment to see what is best for your image. Select Under Format Options, choose Baseline Optimized for best color quality. Choose Progressive to display the image gradually as it downloads from the web browser. Click OK.