Sometimes we’ve had nasty presentation day surprises because colors we use in PowerPoint presentations get changed to other, very different colors, apparently when our presentations got made on our desktop machines and then displayed through a dedicated laptop up at the podium, or perhaps when a “template” gets imposed upon them.
What causes this? How do we avoid it? Is this limited to PowerPoint entities (such as arrows or lines or text), or can it happen to imported graphics? Perhaps graphics that use color palettes (256 color) as opposed to RGB (24bit) get different palettes entangled? I can’t easily reproduce the problems and don’t see it discussed per se on the PPT web site I found.
There is another problem that different monitors introduce shading differences, especially between CRTs and LCDs and various projector types. I’m not talking about these shifts, I’m talking about when the colors just go crazy, for example bright red and bright blue get traded.
I have found that the main cause of unexpected color shifts in Powerpoint has to do with the Slide Master (View–>Master–>Slide Master). If a graphic is created in a file with one Slide Master, and then the graphic is copied to another presentation with a different Master, then the colors will all shift to those specified in the new Master.
Really the only way to avoid having to recolor everything everytime this happens is to get everybody to use the same Slide Master.
What you’re referring to is the Slide Color Scheme. The problem you describe usually occurs when slides that were created with a defined color scheme set in PowerPoint are inserted into another presentation with a different scheme set.
People usually set the slide color scheme to ensure that all elements used in their presentation are consistent by automatically using the colors set in the scheme. It saves time when creating the presentation. Usually it’s not a problem because slides are usually added manually, and any slide added manually inherits the slide color scheme that was set for the deck.
Most infrequent/inexperienced PowerPoint users don’t set the slide color scheme. Heck, most have never even heard of it. As long as no scheme is set for the deck inserting slides from another deck won’t be a problem because there’s no scheme to inherit.
This problem only affects elements created in PowerPoint, not imported graphics like jpegs, PNGs, Tiffs, or GIFs.