Finally, a D300 Near UniWB JPEG

Started Apr 3, 2008 | Discussions thread
antimonite Regular Member • Posts: 144
Re: Contrast and saturation

GaborSch wrote:

What about uploading the raw file, so that I can take a look at it in

Sorry for the late answer, been out some days. Unfortunately it is not possible to upload the NEF file to Picasa. In the meantime I have taken some shots with a neutral tone curve 1:1 (not the reverse gamma because I compare sRGB histograms) and a WB 5000K G6 A1, which gives 258, 256, 264, 256. I have also applied no sharpness and neutral saturation and …I still have serious discrepancies in black level clipping with the blue channel, and red channel white level clipping.

Of course we cannot compare the histogram shapes because:

  • The raw has a bit count logarithmic scale and the camera one is lineal.

  • The camera histograms values are 8 bits, the raw are 12 or 14 shown over a 256 positions scale. (If I am not wrong)

  • The demosaicing influence in the bit count.

But the tendency of the distribution has to be the same.

On the other hand I have noticed that the D300's black level recorded on the RAW file is always 0 as well as the black point. The green channel white level is always about 3840, a 25% less than the other channels. According to Sony/Nikon information the A/D conversion is done by columns and there is only one kind of photodiodes, so in theory the white level has to be the same in all the channels. Going now to the black point, even with the transistor reset the base photodiode noise spread has to be there. Some information is missing in the RAW file. I have seen in your web page that you have found something similar with the D2X.

I give up. I think that with my D300 it will be near impossible to judge the sensor clipping through the in camera histogram.

Best regards, congratulations for your excellent PhotoBola Raw Image Analysis.


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