A large Impress file can be difficult to email, upload, or open on an older computer. In a deck full of photos, the most effective first step is usually to compress the images that are much larger than their on-slide display size. Impress includes a per-image compression dialog where you can adjust JPEG quality, change pixel dimensions, and calculate an estimated new image size. Work on a copy, change only what the slides can tolerate, then save and inspect the finished presentation.
Use Impress's built-in Compress command when the presentation is already assembled and you want to reduce the size of selected embedded images without rebuilding the deck. If the images are still under your control and many are oversized, resizing and optimizing them before inserting can be faster and gives you more control over image format and crop. Either way, keep an untouched copy until you have checked the slides at presentation size.
Compression is not equally suitable for every graphic. Photographs often tolerate moderate JPEG compression. Logos, diagrams, screenshots, and text-heavy images can show visible artifacts around fine edges, so preserve them at full quality or use a lossless source where practical. LibreOffice's help distinguishes lossy compression, which trades some image information for smaller files, from lossless compression, which preserves the original data. The size reduction depends on each image's format and content; there is no guaranteed percentage.
Open the presentation and save a working copy first. Select one image on a slide, then choose Format > Image > Compress. Depending on the interface layout and context, the command may also appear in the selected image's context menu or on the Image tab. The current LibreOffice Help documents all three entry points. If you do not see the command, confirm that the picture itself is selected rather than a group, placeholder, or slide background.
The Compress Image dialog reports image information and offers controls for JPEG quality and resolution. It acts on the selected graphic; repeat the process for other large images that matter. Start with the biggest photographs or background images, because tiny icons are unlikely to account for much of the presentation's total size.
For JPEG images, the quality slider runs from 0 to 100. LibreOffice Help describes 90 as the default and says lower values can reduce image data while reducing visual quality. Treat that as a starting point, not a universal best setting: the visible effect depends on the image. Try a modest reduction first, calculate the new size, and inspect the slide at full-screen or projected size. If faces, fine textures, or text edges look smeared, undo the change or raise the quality.
For a photo that is several thousand pixels wide but displayed in a small area, check Change image resolution and set dimensions closer to what the slide needs. Use the displayed width and height fields together, preserve the image's aspect ratio, and avoid enlarging an image beyond its original pixel dimensions. A full-bleed photograph needs more pixels than a small thumbnail. There is no single pixel target for every deck: output size, screen or projector resolution, cropping, and how close viewers sit all matter.
The dialog's resolution control is expressed as pixel density (DPI), and it also offers an interpolation choice. Changing DPI metadata alone does not necessarily make an image's pixel dimensions smaller. To reduce stored image data, enable the resolution change and set smaller width and height values when appropriate; then use Calculate New Size to review the estimate. The help page describes this estimate as based on the dialog settings. It is an estimate for the selected image, not a promise about the final presentation size.
Usually, this is not the control to prioritize. LibreOffice documents PNG compression as lossless and notes that a lower compression factor may be useful when saving on a slow computer; the decompressed image does not depend on the compression level. For a large presentation, focus first on whether a PNG is appropriate for the content and whether its pixel dimensions are excessive. Do not convert crisp screenshots, diagrams, or transparent graphics to JPEG just to reduce size if compression artifacts would harm legibility.
Photos are common contributors, but they are not the only ones. Look for unused slides, duplicated images, oversized backgrounds, embedded media, and imported objects that are no longer needed. Delete content only after confirming that it is not used in hidden slides, transitions, or later sections. If the deck includes audio or video, inspect those files separately; image compression will not shrink media objects. Avoid assuming that cropping a picture on the slide removes all of its original pixels. If the image remains large afterward, use the compression dialog or prepare a smaller cropped copy in an image editor.
For a deck with many images, check one or two representative slides first. If the selected-image command reduces those images enough while keeping them clear, continue with the other oversized items. If the dialog's estimate is small or the pictures already look soft, stop and try different images or reduce redundant content instead. Repeatedly lowering quality can produce visible damage without meaningfully changing a file whose size comes from embedded video or other objects.
Compare files only after saving; an estimate inside the dialog is not the final package size. The container format, other embedded content, and the changes you made all affect the final result. If you deliver a PDF, export it separately and check the PDF's size and visual quality too. A smaller Impress source does not guarantee a proportionally smaller PDF.
Keep an editable Impress copy in the format your collaborators expect, and test the saved file in the application or viewer they use. Saving to another presentation format can change compatibility or layout and should not be treated as an image-compression method by itself. If you need a shareable viewing copy, export a PDF and inspect it independently. Maintain the uncompressed original until the recipient confirms that the reduced copy opens and looks right.
The practical goal is not the smallest file at any cost. It is a file that is easier to store or send while its photographs remain clear and its diagrams and labels remain readable. Compress selectively, compare the actual saved file, and let a full-screen review decide whether a setting is acceptable.
Create an Outlook meeting invite, add required or optional attendees, choose a time, add Teams details, set recurrence, and check replies in new or classic Outlook.
Use Excel's Data Validation settings to set a maximum, minimum, exact length, or character range, then add clear prompts and error alerts.
Fix the Outlook “We can’t schedule the meeting” error by checking account support, refreshing Teams sign-in, and repairing the Classic Outlook add-in.
Change Office 365 menus, spelling and grammar settings, or keyboard input in desktop apps and Microsoft 365 for the web.
Learn how to auto-forward all or selected emails in Outlook 365 using Forwarding settings or Rules, plus how to stop forwarding and fix blocked external forwards.
Use Microsoft Editor in Word for Microsoft 365 to check spelling, grammar, clarity, and conciseness, review suggestions, and tune proofing settings.
Learn how to add an RSS feed to Outlook 365 in classic Outlook for Windows, find the correct feed URL, manage subscriptions, and fix common RSS issues.
Jump straight to any page in Word for Microsoft 365 with Ctrl+G or F5, relative page numbers, or the Navigation pane, with Windows and Mac shortcuts.
Learn how to add contacts to Outlook on the web, new Outlook, classic Outlook, and mobile, plus how contact syncing and CSV imports work.
Change a Word page color, add a picture background, remove either, and enable background printing on Windows or Mac with clear, current steps.
