This is an old introduction to the channels-first/channels-last features:
  
      

      Machine Learning Mastery – 4 Apr 19
  

  
    

A Gentle Introduction to Channels-First and Channels-Last Image Formats 1

  Color images have height, width, and color channel dimensions. When represented as three-dimensional arrays, the channel dimension for the image […]

  
    Est. reading time: 10 minutes
  

  

  
    
    
  

  


You can convert data between channels-first and channels-last with a ‘permute dims’ tensor call. This can be done with a Lambda layer.