The sensor in a Nikon D850 is covered with a so called colour filter array using a Bayer Pattern. Choosing the widest gamut camera color space (Adobe RGB usually) available, setting uni-wb and using the lowest contrast setting available (including removing any sharpening) will all help to give a closer approximation. The histogram that you look at when viewing the file, post capture, is probably calculated from the JPEG preview file embedded within the raw file itself.Īlmost always, the in-camera histogram, after this extensive processing, will not help you perform ETTR as it will show clipping at the right side of the image well before the raw data is actually clipped. To make the JPEG, the camera performs the additional 8×8 discrete cosine transform, file compression and formats the data in the nominated pattern for a JPEG file format. In live view it is likely that the camera sub-samples (to make the calculation faster) and assigns the pixels to buckets. What may be happening is that the histogram that you see is derived from only a part of the image processing chain that produces the JPEG file. It’s difficult to know, for certain, exactly how the in-camera histogram (prior to the shot being taken) is really calculated. These changes frequently lead to a pessimistic assessment of what the RAW file actually contains, leading to apparently blown out highlights for channels that are not really fully saturated in the RAW data. User Chosen Picture Controls or Settings (Contrast, Saturation, Sharpening etc).Colour Profile Conversion (sRGB, Adobe RGB).The correlation between the information in the JPEG file and the RAW file depends upon the modifications that occur during the processes of: This is because the histogram is taken from a version of the JPEG file that the camera produces (stored inside the RAW file). Sadly the histogram and clipping information (blinkies) do not closely relate to the information captured in a RAW file. But how much difference does this make in practise, and crucially, is it useable? What is Uni-White Balance? BackgroundĬhecking the histogram and the clipping information is part of everyday routine for many photographers. A larger difference can be made by using, so called, uni-white balance. Unfortunately this only takes you so far. Setting a neutral picture control, with flat contrast and zero sharpening, is itself a way to improve the accuracy of the in-camera histogram, because it limits extra white point and black point clipping. This jpeg processing, in turn, is determined by the picture control that you have selected in-camera. Uni-white balance is a way of improving the exposure information from your on-camera histogram, which is based on the jpeg processing currently in force when you take your shot. I’m very much in favour of using an ETTR (expose to the right) methodology with all my RAW shooting. Uni-White Balance on a D850 How Much Difference Does it Make to Assessing ETTR?
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