declare @Temp Table (Fld1 image NULL) INSERT INTO @Temp VALUES (NULL) SELECT CASE WHEN SUBSTRING(Fld1,1, 3) = Char(255)+Char(216)+Char(255) THEN 'JPG' WHEN SUBSTRING(Fld1,1, 3) = 'GIF' THEN 'GIF' WHEN SUBSTRING(Fld1,1, 3) = 'EMF' THEN 'EMF' WHEN SUBSTRING(Fld1,1, 3) = 'PNG' THEN 'PNG' WHEN SUBSTRING(Fld1,1, 2) = 'BM' THEN 'BMP' WHEN SUBSTRING(Fld1,1, 3) = 'CWS' AND ASCII(SUBSTRING(Fld1,4, 1)) < 16 THEN 'SWF' WHEN SUBSTRING(Fld1,1, 3) = 'FWS' AND ASCII(SUBSTRING(Fld1,4, 1)) < 16 THEN 'SWF' WHEN SUBSTRING(Fld1,1, 4) = Char(215)+Char(205)+Char(198)+Char(154) THEN 'WMF' WHEN SUBSTRING(Fld1,1, 4) = Char(77)+Char(77)+Char(7)+Char(42) THEN 'TIF' ELSE 'Don''t know' END AS Test FROM @TempTested on SQL Server 2005 only. With tested I mean I run this code and it didn't gave me an error :-)