Apple Macintosh PhotoFlash - Manual (Page 117)

3 Activate the JPEG slider by choosing the appropriate JPEG command from the pop-up
menu or selecting the Use JPEG Compression checkbox.
If you chose Save As TIFF, choose JPEG from the TIFF Compression
pop-up menu.
If you chose Save As EPS or DCS, click the Use JPEG Compression checkbox
to select it.
The JPEG controls become active.
4 Drag the Selected Area Quality slider to select a numbered setting.
This setting will be applied to the area that is currently selected in the image.
A setting of 1 offers the lowest image quality and the most compression
(smallest size of the image file).
A setting of 100 offers the highest image quality and the least compression
(largest size of the image file).
Alternatively, you can choose one of the options from the Selected Area
Quality pop-up menu.
107 Converting and Compressing Files
Selected Area
Quality slider