Filter by background color?

Sub FilterByColor()
Dim r As Range, txt As String
Dim fColor  As Byte

fColor = Range("B1").Interior.ColorIndex
Columns(1).Rows.Hidden = False

Again:
    For Each r In Range("a2", Range("a" & Rows.Count).End(xlUp)).SpecialCells(xlCellTypeVisible)
        If r.Interior.ColorIndex <> fColor Then txt = txt & r.Address(0, 0) & ","
        If Len(txt) > 245 Then
            Range(Left(txt, Len(txt) - 1)).EntireRow.Hidden = True
            txt = Empty: GoTo Again
        End If
    Next
If Len(txt) Then Range(Left(txt, Len(txt) - 1)).EntireRow.Hidden = True
End Sub