PhotoRAW Histograms

[sonwolf]

I do not understand the two histograms in PhotoRAW. The Linear Histogram is the typical image representation used by other raw converters. This histogram is definitely a non-linear representation of the image data so the linear label seems inappropriate. (A true linear histogram would use 50% of its levels to represent the highlights in the brightest exposure stop.) I have no idea what the EV Histogram represents. The Epson instruction manual's cryptic reference to "logarithmic scale" leaves me puzzled.

Can anyone provide a clear explanation?

 

[jl-lb.ms]

Not sure, but perhaps the EV scale (logarithmic) is what you are thinking of as linear? The "linear" scale is linear in that the pixel values are evenly distributed from 0-255 on the x axis, yes?

 

[sonwolf]

John, I can see your logic regarding Epson's use of "linear" for the traditional histogram, though this approach is the polar opposite of what linear usually means.

The images I have examined using the EV histogram do not follow linear proportions across the horizontal axis. Other than an image dominated by bright tones, a linear histogram should be dominated by values in the left half of the scale. The right side of the histogram would only represent the brightest exposure stop, essentially the bright highlights. My images in PhotoRAW are not scaling across the EV histogram according to standard linear rules. Epson, obviously created this histogram based on some type of scaling logic, they just forgot to explain their logic to R-D1 owners. I am not surprised; the R-D1 has the least detailed instructional manual of any digital camera I have owned.

If anyone desires a proper explanation of linear capture and histograms, you can read Bruce Fraser's at Google Books:

http://books.google.com/books?id=dxeaMiTVB-gC&pg=PA6&lpg=PA6&dq=linear+raw+exposure+bruce+fraser&source=web&ots=IvQVZrOIMc&sig=9uVP😵A_Yqycy4bEvdVajFgHu4#PPA8,M1