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Message: <blockquote data-quote="WayneF" data-source="post: 436726" data-attributes="member: 12496">The horizontal lines at each end are just areas of very low pixel count.The horizontal dark line is the few black ducks.  The horizontal bright line is the few bright ducks.    Small areas, not many pixels there to register, and not all the same color to combine and cause a peak.Brightness is shown in histogram from left to right, from darkest possible at 0 at left edge, to brightest possible at 255 at right edge.Height simply shows the count of pixels of each of those 256 brightness values. The "vertical line" at right end of middle peak does NOT denote that it  was clipped.  If it were up against the right edge, it would, but it's  not at the right edge.Obviously is not clipped because the horizontal line of brighter ducks across the middle of the picture are  much brighter than the "vertical line" at the edge of the middle area.   The image is near normally exposed, any more would clip some of those bright ducks (but they are not clipped now).  And the black ducks are darker than the main peak too.Holding ALT key while sliding the Levels White Point (or which is the Exposure slider in Raw) shows that the bright line of ducks is shown across the nearly-but-not-quite-zero portion in the empty top third.    There are a few pixels there (but no height).  The histogram height of the ducks is very low simply because their area (their pixel count) is very small.   This does not detract from their brightness. The histogram is a bar chart of pixel count of each brightness value.The 'vertical line" at right edge of middle peak is seen to be the count of the pixels of the bright sky above that boat in the middle.  It is a larger area pixel count (hence a histogram peak), and the right and left edges of sky are not as bright (not as far to the right).  The plume of the boat is almost as bright, but it is a very tiny area, little impact on the histogram.The blackest is the black ducks.  Then starting around 32 begins the main peak of the dark treeline in the background (larger area, more pixels, more peak).  You can hold ALT key and slide the Black Point (which is "Blacks" in raw) and identify that too.The tallest middle peak is the water... a quite large area of pixels, all in the same brightness range.This is all trivially verified with the ALT key, as described before.Histogram height is NOT brightness.   Brightness is toward the right edge.  Histogram height is just a relative pixel count.   Relative because histograms are automatically scaled so the tallest peak (of pixel count) is always very near full height.I put up a quick screen capture showing how this analysis is done.    Raw Exposure and Blacks will do same thing (same tools).  Enlarging the video to full screen will show better.   This is something we all ought to know.[MEDIA=youtube]YNNbFkvTCes[/MEDIA]</blockquote>

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