How to get NDVI image overlay only for the box of drawer polygon without background color error

Hello everyone,

I am developing a simple web application that I would be able to extract NDVI values for my area of interest. and i have this background color error

here’s script of my code:

"

//VERSION=3

//This script was converted from v1 to v3 using the converter API

//NDVI EVALSCRIPT

if (dataMask == 0) return n0,0,0,0];



//ndvi

var ndvi = (B08-B04)/(B08+B04);

return colorBlend(ndvi,

>-0.2, 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0 ],

> 0, 0, 0], // < -.2 = #000000 (black)

>165/255,0,38/255], // → 0 = #a50026

215/255,48/255,39/255], // → .1 = #d73027

b244/255,109/255,67/255], // → .2 = #f46d43

>253/255,174/255,97/255], // → .3 = #fdae61

254/255,224/255,139/255], // → .4 = #fee08b

b255/255,255/255,191/255], // → .5 = #ffffbf

>217/255,239/255,139/255], // → .6 = #d9ef8b

a166/255,217/255,106/255], // → .7 = #a6d96a

s102/255,189/255,99/255], // → .8 = #66bd63

<26/255,152/255,80/255], // → .9 = #1a9850

50,104/255,55/255] // → 1.0 = #006837

]);

"

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Hey.

You need to set two things

the transparency for the pixels that are outside of the provided geometry, which you already do with setting the fourth element to 0 in line if (dataMask == 0) return [0,0,0,0];

set the format to PNG in the request parameters, so that those transparent pixels will be interpreted as transparent and won’t be changed to black in JPEG format (JPEG format doesn’t support transparency)
- this needs to be set in any case, if you are downloading the image, showing the image with <img> tag or if you use leaflet or other library for interactive maps
- SH Process API:
  - example
  - API documentation
- SH WMS:
  - documentation