Retrieve projection inside .map() GEE

Question

When using a reducing function such as .reduceRegion(), a provided projection is necessary.
This projection has to be provided as  CRS String, and crsTransform List. Both are optainable with :
var proj = Im.projection().getInfo()
var crs = proj.crs
var transform = proj.transform

yet the Funktion .getInfo() is not usable inside .map(), due to its correspondence with the Javascript Interface of Google Earth Engine.
To call the projection with the designated ee.Projection() functions is not possible, due to the expectations of .reduceRegions()
var proj = Im.projection()
var crs = proj.crs()
var transform = proj.transform()

how can a projection Inside the .map() function be retrieved for usage inside .reduceRegion()?
var min = Im.reduceRegion({
  reducer:ee.Reducer.min(),
  crs:crs,
  crsTransform:transform,
})

JonasV · Accepted Answer

You do not need to specify crsTransform if use the same transform as given in the projection you passed to crs. Furthermore, if you don't set a different crs than supplied by the image you are mapping over, you don't need to specifically define a crs at all. In this case the crs will be taken from the Image you are calling reduceRegion() on. But in case you want to take the projection from a different image this should work just fine in a .map call:
// Different Image from which you take the projection    
var proj = Im2.projection()

var min = Im.reduceRegion({
  reducer:ee.Reducer.min(),
  crs: proj
})

Retrieve projection inside .map() GEE

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