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Bitwise Left Shift function

Available with Image Analyst license.

Available with Spatial Analyst license.

Overview

Performs a Bitwise Left Shift operation on the binary values of two input rasters.

Learn more about how Bitwise math tools work

Bitwise Left Shift illustration
Bitwise Left Shift InRas1 by a constant of 1.)

Notes

Two inputs are necessary for this function to execute.

The order of the inputs is irrelevant for this function.

If an input is floating point data type, the values are converted to integer values through truncation before the bitwise operation is performed.

All bitwise operations have the following in common:

  • Binary values are stored in two's complement.
  • The tools work on 32-bit integers.
  • The leftmost bit position is reversed for the sign (positive or negative) of the value. If the integer is positive, the bit position is 0; if it's negative, the bit position is 1.

The Bitwise Left Shift operation does no wrapping of bits. The leftmost bit is dropped.

Parameters

Parameter nameDescription

Raster

The input on which to perform the shift.

A constant value can be used as an input for this parameter, provided a raster is specified for the other parameter.

Raster2

The input defining the number of positions to shift the bits.

A constant value can be used as an input for this parameter, provided a raster is specified for the other parameter.

Extent Type

Choose which extent should be used in the output raster:

  • First Of—Use the extent of the first input raster to determine the processing extent.

  • Intersection Of—Use the extent of the overlapping pixels to determine the processing extent. This is the default.
  • Union Of—Use the extent of all the rasters to determine the processing extent.
  • Last Of—Use the extent of the last input raster to determine the processing extent.

Cellsize Type

Choose which cell size to use in the output raster. If all the input cell sizes are the same, all the options will yield the same results.

  • First Of—Use the first cell size of the input rasters.
  • Min Of—Use the smallest cell size of all the input rasters.
  • Max Of—Use the largest cell size of all the input rasters. This is the default.
  • Mean Of—Use the mean cell size of all the input rasters.
  • Last Of—Use the last cell size of the input rasters.

Learn more about bitwise

The bitwise tools evaluate the binary representation of the input values on a pixel-by-pixel basis. For each bit in the binary representation, a Boolean operation is performed.

The logic of how the various bitwise tools operate is illustrated in the following sections. The arrows are used to indicate the flow of operation of how input values are converted to a base2 binary representation, analyzed, and returned as a decimal (base10) value.

Learn more about how Bitwise Left Shift works

The arrows in the following illustration demonstrate that the input values are first converted to their binary representation, the bitwise logic is applied to each pair of bits that represent those values, and the values are finally converted back to a decimal representation.

For Bitwise Left Shift, the value for each bit is shifted to the left by the number of bit positions specified in the second input. The value that is assigned to the farthest left bit is lost. The effect of a left shift by one bit position is a multiplication by two.

Bitwise Left and Right Shift example
This is a Bitwise Left and Right Shift example.

Note:

If any of the input pixel values is NoData, the output value will be NoData.