tensorflow::ops::Dequantize

Dequantize the 'input' tensor into a float or bfloat16 Tensor.

Summary

[min_range, max_range] are scalar floats that specify the range for the output. The 'mode' attribute controls exactly which calculations are used to convert the float values to their quantized equivalents.

In 'MIN_COMBINED' mode, each value of the tensor will undergo the following:

if T == qint8: in[i] += (range(T) + 1)/ 2.0
out[i] = min_range + (in[i]* (max_range - min_range) / range(T))

MIN_COMBINED Mode Example

If the input comes from a QuantizedRelu6, the output type is quint8 (range of 0-255) but the possible range of QuantizedRelu6 is 0-6. The min_range and max_range values are therefore 0.0 and 6.0. Dequantize on quint8 will take each value, cast to float, and multiply by 6 / 255. Note that if quantizedtype is qint8, the operation will additionally add each value by 128 prior to casting.

If the mode is 'MIN_FIRST', then this approach is used:

num_discrete_values = 1 << (# of bits in T)
range_adjust = num_discrete_values / (num_discrete_values - 1)
range = (range_max - range_min) * range_adjust
range_scale = range / num_discrete_values
const double offset_input = static_cast(input) - lowest_quantized;
result = range_min + ((input - numeric_limits::min()) * range_scale)

If the mode is SCALED, dequantization is performed by multiplying each input value by a scaling_factor. (Thus an input of 0 always maps to 0.0).

The scaling_factor is determined from min_range, max_range, and narrow_range in a way that is compatible with QuantizeAndDequantize{V2|V3} and QuantizeV2, using the following algorithm:

  

  

    
  const int min_expected_T = std::numeric_limits::min() +
    (narrow_range ? 1 : 0);
  const int max_expected_T = std::numeric_limits::max();
  const float max_expected_T = std::numeric_limits::max();
  

  

    
  const float scale_factor =
    (std::numeric_limits::min() == 0) ? (max_range / max_expected_T)
                                         : std::max(min_range / min_expected_T,
                                                    max_range / max_expected_T);

  

  
Arguments:

      
scope: A Scope object
      
min_range: The minimum scalar value possibly produced for the input.
      
max_range: The maximum scalar value possibly produced for the input.
    

  
Optional attributes (see Attrs):

      
dtype: Type of the output tensor. Currently Dequantize supports float and bfloat16. If 'dtype' is 'bfloat16', it only supports 'MIN_COMBINED' mode.
    

  
Returns:

      
Output: The output tensor. 
    

  

    

      

        
Constructors and Destructors
      
    
    

      

        Dequantize(const ::tensorflow::Scope & scope, ::tensorflow::Input input, ::tensorflow::Input min_range, ::tensorflow::Input max_range)
        

      
    
    

      

        Dequantize(const ::tensorflow::Scope & scope, ::tensorflow::Input input, ::tensorflow::Input min_range, ::tensorflow::Input max_range, const Dequantize::Attrs & attrs)
        

      
    
  
  

    

      

        
Public attributes
      
    
    

      

        operation
      
      

        

          Operation
        
      
    
    

      

        output
      
      

        

          ::tensorflow::Output
        
      
    
  
  

    

      

        
Public functions
      
    
    

      

        node() const 
      
      

        

          ::tensorflow::Node *
        
      
    
    

      

        operator::tensorflow::Input() const 
      
      

        

          
        

      
    
    

      

        operator::tensorflow::Output() const 
      
      

        

          
        

      
    
  
  

    

      

        
Public static functions
      
    
    

      

        Axis(int64 x)
      
      

        

          Attrs
        
      
    
    

      

        Dtype(DataType x)
      
      

        

          Attrs
        
      
    
    

      

        Mode(StringPiece x)
      
      

        

          Attrs
        
      
    
    

      

        NarrowRange(bool x)
      
      

        

          Attrs
        
      
    
  
  

    

      

        
Structs
      
    
    

      

        tensorflow::ops::Dequantize::Attrs
      
      

        
Optional attribute setters for Dequantize. 
      
    
  
  
Public attributes
  

    
operation
    
Operation operation
    

  
  

    
output
    
::tensorflow::Output output
    

  
  
Public functions
  

    
Dequantize
    
 Dequantize(
  const ::tensorflow::Scope & scope,
  ::tensorflow::Input input,
  ::tensorflow::Input min_range,
  ::tensorflow::Input max_range
)
    

  
  

    
Dequantize
    
 Dequantize(
  const ::tensorflow::Scope & scope,
  ::tensorflow::Input input,
  ::tensorflow::Input min_range,
  ::tensorflow::Input max_range,
  const Dequantize::Attrs & attrs
)
    

  
  

    
node
    
::tensorflow::Node * node() const 
    

  
  

    
operator::tensorflow::Input
    
 operator::tensorflow::Input() const 
    

  
  

    
operator::tensorflow::Output
    
 operator::tensorflow::Output() const 
    

  
  
Public static functions
  

    
Axis
    
Attrs Axis(
  int64 x
)
    

  
  

    
Dtype
    
Attrs Dtype(
  DataType x
)
    

  
  

    
Mode
    
Attrs Mode(
  StringPiece x
)
    

  
  

    
NarrowRange
    
Attrs NarrowRange(
  bool x
)