如何使用Pset讀取BMP圖檔某個位置某個顏色值?(編號：1138)

使用了Pset讀取BMP圖檔,如下但不知如何讀取某個位置某個顏色值.
Private Sub Picture1_Click()
Dialog.Filter = "BMP(*.bmp)!*.bmp"
Dialog.ShowOpen
Picture1.Picture = LoadPicture(Dialog.FileName)
For Y = 0 To Picture1.ScaleHeight Step 15
For X = 0 To Picture1.ScaleWidth Step 15
Picture1.PSet (X, Y)
Next
Next
Print Y
Print X
Picture1.Picture = LoadPicture(Dialog.FileName)
End Sub