The uncompressed picture pdf file is slightly larger. To reduce the size of a PDF, you can

Method 1: Please install Adobe Acrobat XI Pro software, and use the Tools-Operations-Optimize Scan Document option to process documents and compress the PDF file size.

Method 2, compress with nxpowerlite pdf, which has a wide compression range:

1, install nxpowerlite software,

2. Open nxpowerlite software.

3. Press the "Add File" button and select the file you want to compress.

4. Just press "Optimize".