Sentinel NDVI timelapse

Question

I'm trying to make a 5-year timelapse of monthly NDVI composites. I apply a Hollstein mask, make composites and fill the masked area with mean NDVI pixels of the entire timeperiod. Of course this method is questionable, and there are many ways, but I am mostly stuck on producing the timelapse video itself. I use the GIF production because I only use one band. In GEE my composites look like this: But when I produce a GIF timelapse, it looks like this:

I tried multiplying the NDVI by 100 to see whether that would induce more colour contrast, I tried to add more colours to the visualisation parameters, but the contrast remains the same.

Code: https://code.earthengine.google.com/dd50d25333a7ff8be05f76733bac6c3c

Answer 1

There are 2 bugs in your code:

1. imgColMeanFilled has a dynamic range from -100 to 100. It is -100 to 100 because on line 25, you multiply the NDVI output by 100. However, to visualize the gif you have set the range from -1 to 1 which clips most of the image's range. Set it to -100 to 100 inside visParams on line 110.
2. On line 103 you are multiplying an image with a range of -100 to 100 by 512. That makes the range -51200,51200. But then you convert it to unsigned 8 bit integer that has a range from 0 to 255. This results in the values getting clipped to 0 and 255. Instead, do not convert to unsigned integer.

With that, the result is as expected in gif. Link to corrected code.