It is my understanding that imageCollection.reduce() takes an image collection -collection of images over time, where at any given time the image is/can-be consist of several bands- and then reduces it by acting in time dimension. In other words, for any given band like B1, it does the reduction over the time window from t_1 to t_n, and generates an image which has lost its time dimensionality, but has the same number of bands as original ImageCollection object.

And Image.reduce() which acts on a single image, single image being an object that is snapshot at a given time-i.e. there is no time dimensionality here to begin with- and then reduces the image, by acting on the band dimensionality. So, output will be like a 2D matrix consisting of just one value per pixel.

Question:

What does this sentence mean here, it is confusing to me (it comes from Image Reductions documentation page): The output is also an image with number of bands equal to number of reducer outputs

P.S. if you are going to edit my question and un-bold the "Question", tell me why you do not like bold font!

It is my understanding that imageCollection.reduce() takes an image collection -collection of images over time, where at any given time the image is/can-be consist of several bands- and then reduces it by acting in time dimension. In other words, for any given band like B1, it does the reduction over the time window from t_1 to t_n, and generates an image which has lost its time dimensionality, but has the same number of bands as original ImageCollection object.

And Image.reduce() which acts on a single image, single image being an object that is snapshot at a given time-i.e. there is no time dimensionality here to begin with- and then reduces the image, by acting on the band dimensionality. So, output will be like a 2D matrix consisting of just one value per pixel.

What does the sentence below mean at the Image Reductions documentation page?

The output is also an image with number of bands equal to number of reducer outputs.