Turn off picture compression
To keep the maximum picture quality, you can turn off compression for all pictures in a file. However, turning off compression can cause very large file sizes without an upper limit on the size of the file.
Click the File tab.
Under Help, click Options, and then click Advanced.
Next to Image Size and Quality, click the file that you want to turn off picture compression for.
Under Image Size and Quality, select the Do not compress images in file check box.
To compress a picture or set other picture quality or resolution options, see Reduce the file size of a picture.