DynamicDequantize

DynamicDequantize operation converts a quantized (s8 or u8) tensor to a f32 tensor. It supports both per-tensor and per-channel asymmetric linear de-quantization. Rounding mode is library-implementation defined. Unlike the Dequantize, DynamicDequantize takes scales and zero-points as operator src tensors.

For per-tensor de-quantization

$$dst=(src-zps)\ast scales$$

For per-channel de-quantization, taking channel axis = 1 as an example:

$${\mathrm{dst}}_{\cdots ,i,\cdots ,\cdots }=({\mathrm{src}}_{\cdots ,i,\cdots ,\cdots }-zp{s}_i)\ast scale{s}_i,i\in [0,channelNum-1]$$

Operation Attributes

Attribute Name	Description	Value Type	Supported Values	Required or Optional
qtype	Specifies which de-quantization type is used	string	per_tensor (default), per_channel	Optional
axis	Specifies dimension on which per-channel de-quantization is applied	s64	A s64 value in the range of [-r, r-1] where r = rank(src), 1 by default	Optional

Execution Arguments

The inputs and outputs must be provided according to the below index order when constructing an operation.

Inputs

Index	Argument Name	Required or Optional
0	src	Required
1	scales	Required
2	zps	Optional

@note scales is a f32 1D tensor to be applied to the de-quantization formula. For qtype = per-tensor, there should be only one element in the scales tensor. For qtype = per-channel, the element number should be equal to the element number of src tensor along the dimension axis.

@note zps is a 1D tensor with offset values that map to zero. For qtype = per-tensor, there should be only one element in the zps tensor. For qtype = per-channel, the element number should be equal to the element number of input tensor along the dimension axis. If not specified, the library can assume the operator is symmetric de-quantization and perform kernel optimization accordingly.

Outputs

Index	Argument Name	Required or Optional
0	dst	Required

Supported Data Types

DynamicDequantize operation supports the following data type combinations.

Src	Dst	Scales	Zps
s8	f32	f32	s8, u8, s32
u8	f32	f32	s8, u8, s32