RE: Digital IR Testing

[Jason Revell <jason.revell@xxxxxxxxx>]

>>--- Gavin O'connor <ogavin@xxxxxxxxxxx> wrote:

>>I then used two test targets
>> a grey scale and a colour chart.
----------
>These targets differ visibly but how about in the 700-1000 nm NIR range
that
>you are interested in? Are there other materials that will provide known
>wide variation in this NIR range? 

My experience has shown that the Standard Kodak grey scale appears the same
in Near IR as to visiable (apart from HSI's slightly higher contrast).
However a Kodak Colour Control Patch is realy quite different as each of the
dyes behaves iferently to the IR wavelengths.

My only thought on this is, if Gavin is just looking at the IR sensativity
of the Camera, wether that reflectance is from a colour source or a grey
(B+W) source surely makes no difference as it will all be recorded in a Grey
tone anyway.  As long as they stay constant for all the test's you will get
an idea of the sensativity of the camera (I presume the test will be done
quite a few times with each camera and the results averaged.  This will also
give an idea of how accurate the test is).  However if it were to be done to
a scienficic level I would strongly suguest measuring the IR reflectance of
the subject matters with a spectrometer first at various the wavelengths.

The proposed method will give a good idea though of what each camera is
recording, though I would be suprised if their is a lot of difference
between them, or at least enough of a difference to make a perceviable
differnce to the image anyway.

Jason Revell
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