If this is full motion capture, perhaps change the setting to 32 bit? (Edit > Preferences > Recording > Full Motion Recording
Or if it's not Full Motion Recording, perhaps select the slides in question, right-click them and change the Video Quality.
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Nope theres no full motion video involved.
I've checked the settings of the slides and theyre set to high quality by default.
I have 'kinda' found a fix...
I select all the background BMP's in my library, i export all.
Then I create a simple action in Photoshop to open up a BMP, change it to a JPEG and then save it.
That gets done quickly with the Batch action. But then I have to manually import each graphic back into Captivate, cant right click and choose update as the background graphic (which was a bmp) is now a jpeg.
Anyway I've replaced all 82 BMP's with 82 JPEG's and it works, white background, the typing animation and mouse moving around dont have a flickery white horizontal line.
Complete pain though, in 'code view' all the backgrounds looked white, the second i preview 5 slides or publish it the off-grey appeared before I did the above.
Slow process to fix, which there was an obvious reason why it did this in the first place