The way I did this was by looking at the number of different colors in a given picture. If it was under 4,000 it was nighttime. For sure. Until December 14th. On that day the construction workers started leaving a light on that pushed the number of colors up close to 10,000. Day shots generally have 45,000-60,000 different colors (yes, in one picture). However, upping my "border" value between day and night to 10,000 pretty eliminated any fades, and still included the night shots with the light on.
Hence, a different method has to be chosen. I have two choices, so far as I can tell. First, determine the average lightness of a picture to decide if it ought to be included in the time lapse. Second, figure out when the construction hours are, only include those pictures and write my own script for fades. The former is much easier.
For a visual idea of what "lightness" looks like in a photo I have posted an Excel graph below. The scale on lightness of is out of 255 for technical reasons so I put a couple of percentages in to make it easier to read. Essentially, during the day the lightness is always between 55% and 63%. A lightness of zero is complete blackness, and a lightness of 100% would be pure white, so finding that the average lightness is somewhere in the middle isn't a big surprise.
The vertical axis is the lightness value of a picture (one grabbed every minute) and the horizontal axis is what minute of the say it is. A day has 1,400 minutes, so 7,200 is high noon. You can see how the day widens and narrows from the fall through the spring, although I should note that the values from October and May in the graph are not complete. Hence, I expect that the May curve would widen out a bit. Finally, the horizontal axis doesn't start at 0 or end at 1,400. They are just straight lines before and past those points respectively, so I cut them out.
P.S. I may move back to madjon.net soon. Maybe, designing a website isn't easy... But I'm also not a huge fan of Blogger anymore.
No comments:
Post a Comment