To save files in the JPEG 2000 format, you must get the optional JPEG 2000 plug‑in and install it in this location: Adobe Photoshop CS3/Plug‑Ins/File Formats. This plug‑in is available from the Photoshop CS3 installation CD in Goodies/Optional Plug‑Ins/File Formats. Extended JPEG 2000 (JPF) format provides an expanded set of options compared to the standard JPEG 2000 (JP2) format. However, you can make files JP2 compatible by selecting the appropriate option in the JPEG 2000 dialog box.
If you specify an image quality that conflicts with a target file size you entered previously, Photoshop automatically changes the value in the File Size text box.
After the alpha channel is loaded as a region of interest, choose an Enhance value to increase or decrease the quality of the region of interest relative to the rest of the image. Note that Enhance does not change the file size of the image, so enhancing the area inside the alpha channel decreases the quality of the area outside the alpha channel (and vice versa).
The Region Of Interest and Enhance options are not available if your Photoshop document does not have an alpha channel.
You can use the Set Preview Zoom pop‑up menu to zoom in or out of the image for better viewing. You can also use the Zoom tool and the Hand tool to adjust the viewing area of your preview.