Compress all embedded TIFF, BMP, EMF etc. images to PNG or JPG
When users copy and paste images into PowerPoint, e.g. from screenshots, these are inserted into the file as uncompressed .TIFFs. Add a few of these, and the file size starts going way up, but the average user will not realise why. Sometimes users will insert bitmap format files such as EMF, BMP into presentations, not knowing that these could have been reduced in size by converting to a different format.
Currently, the Compress Images tool (in Picture Format tab, or in the Save As dialog) doesn't dabble in formats. It only reduces file size where the image has been cropped in place (deleting the cropped areas from the file), or where a the user asks it to reduce the resolution.
These have no effect in a file that is full of TIFF, BMP, WMF, EMF etc. images.
I propose a tool (probably built into the existing compress images tool) that converts uncompressed formats either to PNG, or if some AI analysis is possible, then PNG or JPEG, depending on the material in the image. It is already possible with a relatively short PowerShell script, so shouldn't be difficult to provide to end users in the GUI.
This would easily take a file of 50MB down to, say, 8MB in a few seconds, and cause minimal change to how the images look in the presentation.
Tony Furnell commented
Correction: files inserted from a screen grab may be inserted as PNGs, *not* as uncompressed bitmaps. I don't have full clarity on how the uncompressed formats arrive in a PPTX file, but they do occur (and regularly in my experience). A likely source is when selecting an area of image data, such as in Paint or other imaging software.
Clarification: the existing Compress Images tool *does* affect some TIFF files, however it appears to only be when these files meet the parameters set on the tool. So if a 5MB TIFF doesn't have a cropped area to be deleted, and is of lower resolution than the specified resolution in the tool, it will not be affected and will remain at 5MB. Multiply that 5MB up a few times and you still have an enormous file, hence the above idea.