Compressing images means reducing the quality (resolution). But why would we intentionally make the quality worse than it is? The answer is simple: the computer is to blame. Depending on the resolution or size of the image, it can be 5 MB or even 20 MB. For the computer, this means a lot of work and a high memory requirement when many high-resolution images are integrated into a presentation. Sending a large presentation also quickly causes problems.
This can be avoided simply because such a high resolution of an image is not necessary. Most projectors are not capable of transferring this high quality one-to-one onto a wall. This is also true for printouts. It is necessary to keep the quality as good as necessary and not possible; and that is why we compress images!
We have the choice to compress all images at once or individually. This tutorial shows how to do that.
We click on a graphic and select it.
Now we navigate to the Format(Image Tools) tab and click the Compress Images button.
The Compress Images window will open.
At this point we have the choice of compressing only the selected image or all images in the presentation. For this we set a checkmark at Apply only to this image – or not.
As already explained in the chapter Crop graphics, images can be trimmed. PowerPoint does not delete the trimmed and no longer visible areas and saves them in the background. This means that the trimmed image requires the same amount of memory as an uncropped graphic. With a check mark on “Delete cropped image areas” the no longer visible areas are removed. But beware: they cannot be restored later.
Target output denotes the strength of compression. From HD (330 ppi) to e-mail (96 ppi), the image quality can be set accordingly for the suitable purpose.
Click OK to confirm our entries.
Hinweis: Wenn die Präsentation mit den komprimierten Bilder gespeichert wird, lässt sich die Bildqualität nicht mehr verbessern. Die Auflösung (ppi Zahl) kann nur nach unten reduziert werden. Falls Bilder mit einer geringen Auflösung in einer höheren Qualität gespeichert werden, wird PowerPoint keinen Einwand einlegen – eine Verbesserung wird jedoch nicht stattfinden.
Compress with PowerPoint Options (Alternative)
Images can also be compressed in the PowerPoint options. Technically, this is just a different way to achieve the same goal.
We click on the Tab File.
We go to the options located below.
The PowerPoint Options dialog window will open. On the left bar we select the Advanced option.
There we find the heading Image size and quality.
Here we can edit the memory of PowerPoint. If we check a box at “Discard editing data”, cropped images will no longer have the cropped areas saved in the background (as described in point 3. above). This has the advantage that the file does not become unnecessarily large. Whether this is useful, every PowerPoint user must decide for himself.
The Set Default Target Output option sets the resolution of the graphics for the entire presentation. 330 ppi is high-resolution and suitable for HD screens. 220 ppi is suitable for printing, 150 ppi for web pages and projectors, and 96 for email.
Hinweis: Moderne Projektoren können auch in HD projizieren.