thanks, but as i know its not possible to create project parameter https://forums.autodesk.com/t5/revit-api-forum/create-project-parameter-not-shared-parameter/td-p/5150182
if i use this code for getting parameter
Parameter param = ele.get_Parameter(BuiltInParameter.ALL_MODEL_TYPE_IMAGE);
is it ok to define the url of image by string?
param.Set(@"C:\Users\Desktop\12.jpg")