Function subtract_def

pub fn subtract_def(
    src1: &impl ToInputArray,
    src2: &impl ToInputArray,
    dst: &mut impl ToOutputArray,
) -> Result<()>

Calculates the per-element difference between two arrays or array and a scalar.

The function subtract calculates:

• Difference between two arrays, when both input arrays have the same size and the same number of channels:
• Difference between an array and a scalar, when src2 is constructed from Scalar or has the same number of elements as src1.channels():
• Difference between a scalar and an array, when src1 is constructed from Scalar or has the same number of elements as src2.channels():
• The reverse difference between a scalar and an array in the case of SubRS: where I is a multi-dimensional index of array elements. In case of multi-channel arrays, each channel is processed independently.

The first function in the list above can be replaced with matrix expressions:

   dst = src1 - src2;
   dst -= src1; // equivalent to subtract(dst, src1, dst);

The input arrays and the output array can all have the same or different depths. For example, you can subtract to 8-bit unsigned arrays and store the difference in a 16-bit signed array. Depth of the output array is determined by dtype parameter. In the second and third cases above, as well as in the first case, when src1.depth() == src2.depth(), dtype can be set to the default -1. In this case the output array will have the same depth as the input array, be it src1, src2 or both.

Note: Saturation is not applied when the output array has the depth CV_32S. You may even get result of an incorrect sign in the case of overflow.

Note: (Python) Be careful to difference behaviour between src1/src2 are single number and they are tuple/array. subtract(src,X) means subtract(src,(X,X,X,X)). subtract(src,(X,)) means subtract(src,(X,0,0,0)).

Parameters

• src1: first input array or a scalar.
• src2: second input array or a scalar.
• dst: output array of the same size and the same number of channels as the input array.
• mask: optional operation mask; this is an 8-bit single channel array that specifies elements of the output array to be changed.
• dtype: optional depth of the output array

See also

add, addWeighted, scaleAdd, Mat::convertTo

Note

This alternative version of subtract function uses the following default values for its arguments:

• mask: noArray()
• dtype: -1