How to search a image/varbinary field for records that start with a binary pattern

Question

I am trying to find all images that do not start with the magic number ff d8 ff e0 (the signature for jpg) According to the MSDN I should be able to use patindex on my data. However

SELECT TOP 1000 [cpclid]
FROM [cp]
where patindex('FFD8FFE0%', cpphoto) = 0 -- cpphoto is a column type of image

gives me the error

Msg 8116, Level 16, State 1, Line 1 Argument data type image is invalid for argument 2 of patindex function.

What would be the correct way to find records that do not match the magic number of ff d8 ff e0?

UPDATE:

Here is a link to test any suggestions you have.

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I Ross's solution worked in the end with some tweaking on what the query.

SELECT [cpclid]
  FROM [cp]
where convert(varchar(max), cast(cpphoto as varbinary(max))) not like convert(varchar(max), 0xFFD8FFE0 ) + '%'

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I found a even better solution, see my answer.

Answer 1

I found a much simpler solution that runs a lot faster.

SELECT [cpclid] 
FROM [cp]
where cast(cpphoto as varbinary(4)) <> 0xFFD8FFE0