Posted by
Michael Schmid on
Aug 11, 2020; 5:20pm
URL: http://imagej.273.s1.nabble.com/14-bit-NEF-raw-Images-tp5023829p5023835.html
Hi Lee,
if you open a raw image you should expect that you get
(1) no correction for color balance (white balance) and
(2) a linear response, in contrast to RGB/sRGB formats like jpg etc.,
where the response is nonlinear.
(3) There can be some offset, i.e., black won't correspond to pixel
values of zero.
Thus, your raw image will not look like the corresponding jpg or thumbnail.
For quantitative analysis, subtract a dark frame (raw photo with the
lens cover closed, but the same ISO value and exposure time). This is
best done in 32-bit mode. Also take a photo of a white or neutral gray
object under the same light conditions, than you can calculate
correction factors for the colors.
For quantitative analysis, don't apply a nonlinear function. For
viewing, after the above corrections, you may try Process>Math>Gamma
with a gamma value of about 0.5 to approximate the visual impression of
a jpg etc. image.
Michael
_______________________________________________________________________
On 11/08/2020 12:50 am, Lee Berndt wrote:
> Hi:
> I'm trying to open 14 bit Nikon NEF images with little success .... using Import/Raw the file opens but is very small (160 x 120 px) .... if I use bio-formats the image opens but is not the correct size or color .... dcraw reader also opens it but the image is still not right .... can someone help me please ? what am I doing wrong? Thank you and have a great evening .... Lee
>
> William L. Berndt, Ph.D. 7133 Penner Lane. Apt. #40Fort Myers, FL 33907@Dr_Lee_Berndt239.246.0396
>
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