JPEG is the standard format for compressing photographs.
Open an image and choose File > Save
For Web.
Choose JPEG from the optimization format menu.
(Optional) To optimize to a specific file size, click
the arrow to
the right of the Preset menu, and then click Optimize To File Size.
Enter a number in the Desired File Size text box, and select either Current
Settings, which optimizes for the current settings, or Auto Select GIF/JPEG,
which automatically determines whether JPEG or GIF is the better format.
Do one of the following to specify the compression level:
Choose a quality option (Low, Medium, High, and
so on) from the pop‑up menu under the optimization format menu.
Click the arrow in the Quality menu and drag the
Quality pop‑up slider.
Enter a value between 0 and 100 in the Quality box.
The
higher the Quality setting, the more detail is preserved in the
optimized image, but the larger the file size. View the optimized
image at several quality settings to determine the best balance
between quality and file size.
Select Progressive to display the image progressively
in a web browser; that is, to display it first at a low resolution,
and then at progressively higher resolutions as downloading proceeds.
Note: Some browsers do not support progressive JPEGs.
To preserve the ICC profile of the original image in
the optimized file, select ICC Profile.
Some browsers use ICC profiles for color correction. The
ICC profile of the image depends on your current color setting.
If the original image contains transparency, select a
Matte color that matches the background of your web page. Transparent
areas in your original image are filled with the Matte color.
To save your optimized image, click OK. In the Save Optimized As
dialog box, type a filename, and click Save.