Exponentiation
In these operations a scalar is exponentiated by the value of every pixel in a raster band, or the pixel values are exponentiated by a scalar. The raster band is overwritten with the result of the addition.
The operation is provided in a high-level and a low-level format. In the high-level format a raster object, a band identifier and a token are specified, together with the scalar. The operation applies to all pixels and the result is stored in the specified band. In the low-level format the operation is applied to a block of contiguous memory containing a specified number of pixels. The low-level format is useful to chain a number of operations without the overhead of storing intermediate results.
If you want to preserve the original raster band, you should make a copy of the band first.
The operations can be summarized as follows:
| Operation | Description |
| DSpGMPower |
exponent |
| DSpGMSqr | 2 pixel |
| DSpGMSqrt | 1/2 pixel |
| DSpGMExp | pixel e |
| DSpGMBasePower |
pixel |
High-level declarations:
Pixel
value exponentiated
procedure DSpGMPower(const r: TDSpRaster; const band, token: integer;
exponent: TDSpFloat64);
procedure DSpGMSqr(const r: TDSpRaster; const band, token: integer);
procedure DSpGMSqrt(const r: TDSpRaster; const band, token: integer);
Base exponentiated by
a pixel value
procedure DSpGMExp(const r: TDSpRaster; const band, token: integer);
procedure DSpGMBasePower(const r: TDSpRaster; const band, token: integer;
base: TDSpFloat64);
Low-level declarations:
procedure DSpGMSqrUInt32
procedure DSpGMSqrInt32
procedure DSpGMSqrInt64
procedure DSpGMSqrFloat32
procedure DSpGMSqrFloat64
procedure DSpGMSqrtFloat32
procedure DSpGMSqrtFloat64
procedure DSpGMExpFloat32
procedure DSpGMExpFloat64
(const data: pointer; pixels: integer;
fill: TDSpFloat64);
procedure DSpGMPowerFloat32
procedure DSpGMPowerFloat64
(const data: pointer; pixels: integer;
fill, exponent: TDSpFloat64);
procedure DSpGMBasePowerFloat32
procedure DSpGMBasePowerFloat64
(const data: pointer; pixels: integer;
fill, base: TDSpFloat64);
| Parameter | Description |
| r | A valid raster object. It must be opened for write access. |
| band | The identifier of the raster band. The band must exist in the raster, and it can be of any type. The data type can be any 32-bit or 64-bit data type for the DSpGMSqr* operations, and must be 32-bit or 64-bit floating point for the other operations. |
| token | The access token for the raster. The token has to be generated for write access. |
| exponent | The scalar value to which every pixel of the raster band is exponentiated. This value will be converted to the data type of the raster band before the operation. |
| base |
The scalar value which is exponentiated by every pixel of the raster band. This value will be converted to the data type of the raster band before the operation. |
| data | A pointer to a block of memory containing pixels pixel values. |
| pixels | Number of pixels in the data block of memory. |
| fill | The missing data value of the raster band. |