Hot answers tagged banding
As you are taking this on a phone - it has no shutter, instead it scans the CCD matrix (i think top to bottom) to build an image. What you are seeing is the variation in the brightness of the CFL as the camera scans the CCD. these lamps have a running frequency of around 50-60 Hz, as does the picture on your CRT tv (scan frequency).
It would be helpful to know exactly which tool you used to tweak the sky and to see how it looked before. The histogram of you sky looks like it has been posterized, ie. jumping values, and then blurred to fill up the gaps. the causes for this can be working in a 8bit image space, doing multiple operations that should have made decimal values but then ...
The banding is caused by limited information in the sky area. You can confirm this by using the dropper tool on each band - you will probably find only a limited set of RGB values. Edit: have had a look and the blue values are all 235, 236, 237. If there is limited information, blur will merely move the bands around. You have to add some random ...
Horizontal and Vertical Banding Noise (HVBN) is caused by sensor readout, downstream amplification, and ADC. There can be multiple sources of HVBN, some of them cause a relatively fixed pattern, others can cause random pattern. External signal interference is often a source of softer and more random banding. Exactly which causes banding in which sensors ...
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