DynamicDequantize

General

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

\[dst = (src - zps)*scales\]

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

\[{dst}_{\cdots,i,\cdots,\cdots} = (src_{\cdots,i,\cdots,\cdots} - zps_i)*scales_i,i\in [0,channelNum-1]\]

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. Negative value means counting the dimension backwards from the end.	Optional

Execution arguments

The inputs and outputs must be provided according to 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 omitted, zps values are assumed to be zero.

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