Histogram question


I am trying to understand the histogram for that picture.
The x-scale is the luminosity (?) with the dotted line in the middle corresponding to the grey part around the picture. There is a peak there in the histogram which more-or- less correponds to the pavement. However, the jacket of the gentleman is quite dark, and I would expect another (smaller) peak at low values, that I do not see? What am I missing?

Thank you ,
B. Roessli

I would recommend you start using the waveform. It is a far superior way to analyse your image as the data tracks with the image and is not simply a binned account of the pixel values

I took your posted screenshot as a screenshot (heh, dodgy) opened it in rawproc and cropped just the photograph:

So, the spike in the middle of your screenshot histogram are the darker regions of the photograph, but I don’t know how ART is doing the binning to get the low flat line on the left-hand side…

The histogram visualization has different options for plotting the axes in log scales, so whereas I guess what you are showing is in linear X scale?
Anyway, by clicking on the bottom left icon next to the histogram (the one with vertical stripes) art (and RT) will show a pointer to where in the histogram you are while moving around the picture with your cursor.

Yes the scale is linear. In the attached screesnhot, the position of the mouse and of the pointer in the histogram are shown.

I have ART-1.19.3

Another screenshot

Can you share the picture and the arp? Screenshots are notoriously hard to debug…

IMAG0792_e2.jpg.out.arp (10.9 KB)


Thanks. There are two different things going on here:

  1. your histogram is still using a logscale for the x axis. If you switch to linear, everything behaves as expected. Examples:

  2. In log mode, there was a bug in displaying the indicator lines corresponding to the pixel under the cursor. That should be fixed now, thanks for the report!