We have a PDF that we want to reduce the file size. When we select reduce file size, we get a window that reads "document contained image masks that were not downsampled". What does this mean? The 20 page document contains a lot of cut and paste images of maps and site plans that were built in PowerPoint and InDesign. Using Acrobat 9.
What steps do we have to take to correct this so we can reduce the file size?
It means that the images have a vector mask controlling which areas are visible (acting as a crop). These aren't affected by a RFS action as the vector data is as small as it can be, but the warning is shown because if the underlying bitmap image is resampled, there may be some issues around the edges of the mask (e.g. if the mask very accurately cuts out a shape from a background, some pixels of the background may appear if the image PPI is reduced).
I see, we are trying to reduce the file size of 13 Mb. I've tried printing/PDF smallest file size, reduce file size and optimize. None are reducing the size. Is there anything else I can do?