Compress Images in LibreOffice Impress
Large presentation files in LibreOffice Impress are almost always the result of uncompressed, high-resolution embedded images. This guide provides a straightforward walkthrough on how to use LibreOffice’s built-in compression tools to reduce image dimensions, adjust quality levels, and significantly shrink your overall presentation file size without losing noticeable visual clarity.
How to Compress an Individual Image
LibreOffice Impress includes a native image compression dialog that allows you to optimize embedded graphics directly within your slides.
- Select the Image: Open your presentation and click on the image you want to compress.
- Open the Compression Tool: Right-click the image and select Compress… from the context menu. Alternatively, you can go to the top menu and select Format > Image > Compress….
- Choose the Compression Type:
- JPEG Quality: Best for photographs and complex graphics. Set the quality slider between 75% and 85% for a significant reduction in file size with negligible loss in visual quality.
- PNG Compression: Best for logos, icons, and graphics with solid colors or transparency. Choose a compression level from 1 to 9 (9 provides the highest compression).
- Adjust Resolution (DPI):
- Change the Resolution setting based on your presentation’s intended use.
- Set it to 96 DPI or 150 DPI for standard screen displays and digital sharing.
- Keep it at 300 DPI only if the presentation is intended for high-quality physical printing.
- Check the Output: Click the Calculate New Size button to view the estimated file size reduction.
- Apply Changes: Click OK to apply the compression.
Tips for Managing Large Presentation Files
- Compress All Large Media: Repeat the compression process for any other high-resolution images or screenshots across your slides.
- Crop External to Impress: If you only need a portion of an image, crop it using an external image editor before inserting it. Impress retains the hidden portions of cropped images in the file data unless permanently reduced.
- Save As a New File: After compressing images, use File > Save As to write a clean copy of your presentation. This ensures LibreOffice cleans up temporary cache data and writes a completely optimized file.