vif_tools.h

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#pragma once
 
#ifndef VIF_TOOLS_H_
#define VIF_TOOLS_H_
 
#include <stdbool.h>
 
enum vif_scaling_method {
    vif_scale_nearest = 0,
    vif_scale_bicubic = 1,
    vif_scale_lanczos4 = 2,
    vif_scale_bilinear = 3,
};
 
# define NUM_KERNELSCALES 21
 
static const float valid_kernelscales[NUM_KERNELSCALES] = {
    1.0,
    1.0f / 2.0f,
    3.0f / 2.0f,
    2.0f,
    2.0f / 3.0f,
    24.0f / 10.0f,
    360.0f / 97.0f,
    4.0f / 3.0f,
    3.5f / 3.0f,
    3.75f / 3.0f,
    4.25f / 3.0f,
    5.0f / 3.0f,
    3.0f,
    1.0f / 2.25f,
    1.4746f,
    1.54f,
    1.6f,
    1.06667f,
    0.711111f,
    0.740740f,
    1.111111f,
};
 
/* s single precision, d double precision */
 
void vif_dec2_s(const float *src, float *dst, int src_w, int src_h, int src_stride, int dst_stride); // stride >= width, multiple of 16 or 32 typically
 
void vif_dec16_s(const float *src, float *dst, int src_w, int src_h, int src_stride, int dst_stride); // stride >= width, multiple of 16 or 32 typically
 
float vif_sum_s(const float *x, int w, int h, int stride);
 
void vif_statistic_s(const float *mu1_sq, const float *mu2_sq, const float *xx_filt, const float *yy_filt, const float *xy_filt, float *num, float *den,
                     int w, int h, int mu1_sq_stride, int mu2_sq_stride, int xx_filt_stride, int yy_filt_stride, int xy_filt_stride, double vif_enhn_gain_limit, double vif_sigma_nsq);
 
void vif_filter1d_s(const float *f, const float *src, float *dst, float *tmpbuf, int w, int h, int src_stride, int dst_stride, int fwidth);
 
void vif_filter1d_sq_s(const float *f, const float *src, float *dst, float *tmpbuf, int w, int h, int src_stride, int dst_stride, int fwidth);
 
void vif_filter1d_xy_s(const float *f, const float *src1, const float *src2, float *dst, float *tmpbuf, int w, int h, int src1_stride, int src2_stride, int dst_stride, int fwidth);
 
int vif_get_scaling_method(char *scaling_method_str, enum vif_scaling_method *scale_method);
 
// Bilinear scaling (vif_scale_frame_s with vif_scale_bilinear, and
// vif_scale_frame_bilinear_precompute_columns_s/_precomputed_s) builds its
// column tables on the stack and does not support dst_w beyond this. Callers
// with a fixed prescale factor must check their dst_w against this limit at
// init time and fail rather than call into the scaler with a wider output.
#define VIF_BILINEAR_MAX_WIDTH 7680 // covers up to 8K frame width
 
void vif_scale_frame_s(enum vif_scaling_method scale_method, const float *src, float *dst, int src_w, int src_h, int src_stride, int dst_w, int dst_h, int dst_stride);
 
// Precomputes the per-output-column source indices/weight used by bilinear
// scaling. x1a, x2a and dxa must each have room for dst_w elements. The
// table only depends on src_w/dst_w, so callers that scale many frames at a
// fixed resolution (e.g. a feature extractor with a fixed prescale) can
// compute it once and reuse it via vif_scale_frame_bilinear_precomputed_s.
void vif_scale_frame_bilinear_precompute_columns_s(int src_w, int dst_w, int *x1a, int *x2a, float *dxa);
 
// Same as vif_scale_frame_s(vif_scale_bilinear, ...), but using a column
// table already filled in by vif_scale_frame_bilinear_precompute_columns_s
// for this src_w/dst_w instead of recomputing it.
void vif_scale_frame_bilinear_precomputed_s(const float *src, float *dst, int src_w, int src_h, int src_stride, int dst_w, int dst_h, int dst_stride, const int *x1a, const int *x2a, const float *dxa);
 
int vif_get_filter_size(int scale, float kernelscale);
 
void vif_get_filter(float *out, int scale, float kernelscale);
 
void speed_get_antialias_filter(float *out, int scale, float kernelscale);
 
bool vif_validate_kernelscale(float kernelscale);
 
#endif /* VIF_TOOLS_H_ */