Contrast Property
Returns or sets the contrast for the specified picture or OLE object. The value for this property must be a number from 0.0 (the least contrast) to 1.0 (the greatest contrast). Read/write Single.
expression.Contrast
expression Required. An expression that returns one of the objects in the Applies To list.
Example
This example sets the contrast for shape one on myDocument.
Shape one must be either a picture or an OLE object.
Set myDocument = Worksheets(1)
myDocument.Shapes(1).PictureFormat.Contrast = 0.8