If you “save as” a TIF file in powerpoint the output is very low resolution and unsuitable for submission to a journal for publication. However there are alternative approaches. The simple approach is to print the ppt slide to a high quality PDF file then convert the PDF to TIFF.
I use adobe PDF writer as I have a license, but there are lots of excellent free ones. Bullzip PDF writer is good, and gives you options to set the resolution (dpi) of the output graphics. There are reviews of lots at http://www.techsupportalert.com/best-free-pdf-writer.htm
Step by step:
- print to PDF at the highest resolution possible (you may need to go into the printer properties and set to ‘high quality’ or ‘press’ settings, or set a high dpi setting (600 dpi or greater) depending on which PDF printer you use.
- Open in a good image editor (I have a license for photoshop; for free try Gimp or GimPhoto (gimphoto is GIMP with user interface tweaks to make it more PS like)), but there are lots of free options reviewed here. Set resolution for rasterisation to whatever you need
- Flatten layers if needed
- Trim excess white space
- Save as TIFF