how to give height and width of image

Question

hi!
how to give height and widht of image. means i give a image height 100 and width 100. when i insert images that images height and width is changed to 100x100. all images are same height and width. how to write code like this.
please give a solution and give a sample code.
i take like
private function GetImageSize(BY val height as integer,width as integer)
how to write this type function code.please help me. give a function code of GetImageSize()
Thank u sir.