Functions | |
static __INLINE float32_t | arm_bilinear_interp_f32 (const arm_bilinear_interp_instance_f32 *S, float32_t X, float32_t Y) |
static __INLINE q31_t | arm_bilinear_interp_q31 (arm_bilinear_interp_instance_q31 *S, q31_t X, q31_t Y) |
static __INLINE q15_t | arm_bilinear_interp_q15 (arm_bilinear_interp_instance_q15 *S, q31_t X, q31_t Y) |
static __INLINE q7_t | arm_bilinear_interp_q7 (arm_bilinear_interp_instance_q7 *S, q31_t X, q31_t Y) |
Bilinear interpolation is an extension of linear interpolation applied to a two dimensional grid. The underlying function f(x, y)
is sampled on a regular grid and the interpolation process determines values between the grid points. Bilinear interpolation is equivalent to two step linear interpolation, first in the x-dimension and then in the y-dimension. Bilinear interpolation is often used in image processing to rescale images. The CMSIS DSP library provides bilinear interpolation functions for Q7, Q15, Q31, and floating-point data types.
Algorithm
typedef struct { uint16_t numRows; uint16_t numCols; float32_t *pData; } arm_bilinear_interp_instance_f32;
numRows
specifies the number of rows in the table; numCols
specifies the number of columns in the table; and pData
points to an array of size numRows*numCols
values. The data table pTable
is organized in row order and the supplied data values fall on integer indexes. That is, table element (x,y) is located at pTable[x + y*numCols]
where x and y are integers.(x, y)
specify the desired interpolation point. Then define: XF = floor(x) YF = floor(y)
f(x, y) = f(XF, YF) * (1-(x-XF)) * (1-(y-YF)) + f(XF+1, YF) * (x-XF)*(1-(y-YF)) + f(XF, YF+1) * (1-(x-XF))*(y-YF) + f(XF+1, YF+1) * (x-XF)*(y-YF)Note that the coordinates (x, y) contain integer and fractional components. The integer components specify which portion of the table to use while the fractional components control the interpolation processor.
static __INLINE float32_t arm_bilinear_interp_f32 | ( | const arm_bilinear_interp_instance_f32 * | S, |
float32_t | X, | ||
float32_t | Y | ||
) | [static] |
Floating-point bilinear interpolation.
[in,out] | *S | points to an instance of the interpolation structure. |
[in] | X | interpolation coordinate. |
[in] | Y | interpolation coordinate. |
Definition at line 6739 of file arm_math.h.
static __INLINE q31_t arm_bilinear_interp_q31 | ( | arm_bilinear_interp_instance_q31 * | S, |
q31_t | X, | ||
q31_t | Y | ||
) | [static] |
Q31 bilinear interpolation.
[in,out] | *S | points to an instance of the interpolation structure. |
[in] | X | interpolation coordinate in 12.20 format. |
[in] | Y | interpolation coordinate in 12.20 format. |
Definition at line 6806 of file arm_math.h.
static __INLINE q15_t arm_bilinear_interp_q15 | ( | arm_bilinear_interp_instance_q15 * | S, |
q31_t | X, | ||
q31_t | Y | ||
) | [static] |
Q15 bilinear interpolation.
[in,out] | *S | points to an instance of the interpolation structure. |
[in] | X | interpolation coordinate in 12.20 format. |
[in] | Y | interpolation coordinate in 12.20 format. |
Definition at line 6882 of file arm_math.h.
static __INLINE q7_t arm_bilinear_interp_q7 | ( | arm_bilinear_interp_instance_q7 * | S, |
q31_t | X, | ||
q31_t | Y | ||
) | [static] |
Q7 bilinear interpolation.
[in,out] | *S | points to an instance of the interpolation structure. |
[in] | X | interpolation coordinate in 12.20 format. |
[in] | Y | interpolation coordinate in 12.20 format. |
Definition at line 6962 of file arm_math.h.