/* * zoom.c - resize an image to an arbitrary size with filtering * Based on "Filtered Image Rescaling" by Dale Schumacher (public domain). * * This file is part of transcode, a video stream processing tool. * transcode is free software, distributable under the terms of the GNU * General Public License (version 2 or later). See the file COPYING * for details. */ #include "tcvideo.h" #include "zoom.h" #include "src/transcode.h" #include /*************************************************************************/ /* Data structures for holding resizing data (used internally). */ /* A contributor to a single pixel */ struct contrib { int pixel; double weight; }; /* List of all contributors to a single pixel */ struct clist { int n; /* Number of contributors */ struct contrib *list; /* Pointer to list of contributors */ }; /* Data for a resize operation */ struct zoominfo { int old_w, old_h; /* Original width and height */ int new_w, new_h; /* New width and height */ int Bpp; /* Bytes per pixel */ int old_stride; /* Bytes per line (original image) */ int new_stride; /* Bytes per line (new image) */ double (*filter)(double); /* Filter function */ double fwidth; /* Filter width */ int32_t *x_contrib; /* Contributors in the horizontal direction */ int32_t *y_contrib; /* Contributors in the vertical direction */ uint8_t *tmpimage; /* Temporary buffer */ }; /* Convert a double to a 16.16 fixed-point value */ #define DOUBLE_TO_FIXED(v) ((int32_t)((v)*65536)) /* Convert a 16.16 fixed-point value to an integer */ #define FIXED_TO_INT(v) ((v)>>16) /*************************************************************************/ /* FIXME: use a static table for every data related to a filter, * accessed by filter_id; * typedef struct tcvzoomdata_ TCVZoomData; * struct tcvzoom_data { * const char *name; * double support; * double (*filter)(double t); * }; */ /** * tcv_zoom_filter_to_string: * return the human-readable name of a given filter, as string. * * Parameters: * filter: Filter identifier (TCV_ZOOM_*). * Return value: * name of the given filter. DO NOT free() it. * NULL if the filter is unknown/unsupported. */ const char *tcv_zoom_filter_to_string(TCVZoomFilter filter) { const char *name = NULL; if (filter == TCV_ZOOM_BELL) { name = "Bell"; } else if (filter == TCV_ZOOM_BOX) { name = "Box"; } else if (filter == TCV_ZOOM_B_SPLINE) { name = "B_spline"; } else if (filter == TCV_ZOOM_HERMITE) { name = "Hermite"; } else if (filter == TCV_ZOOM_LANCZOS3) { name = "Lanczos3"; } else if (filter == TCV_ZOOM_MITCHELL) { name = "Mitchell"; } else if (filter == TCV_ZOOM_TRIANGLE) { name = "Triangle"; } else if (filter == TCV_ZOOM_CUBIC_KEYS4) { name = "Cubic_Keys4"; } else if (filter == TCV_ZOOM_SINC8) { name = "Sinc8"; } else if (filter == TCV_ZOOM_DEFAULT) { name = "Lanczos3"; } else { name = NULL; } return name; } /** * tcv_zoom_filter_from_string: * return the filter id given its human-readable name, as string. * case insensitive. * * Parameters: * name: name fo the given filter. * Return value: * the corrisponding identifier of the given name. * TCV_ZOOM_NULL if the filter is unknown/unsupported. */ TCVZoomFilter tcv_zoom_filter_from_string(const char *name) { TCVZoomFilter filter = TCV_ZOOM_NULL; if (strcasecmp(name, "bell") == 0) { filter = TCV_ZOOM_BELL; } else if (strcasecmp(name, "box") == 0) { filter = TCV_ZOOM_BOX; } else if (strcasecmp(name, "b_spline") == 0) { filter = TCV_ZOOM_B_SPLINE; } else if (strcasecmp(name, "hermite") == 0) { filter = TCV_ZOOM_HERMITE; } else if (strcasecmp(name, "lanczos3") == 0) { filter = TCV_ZOOM_LANCZOS3; } else if (strcasecmp(name, "mitchell") == 0) { filter = TCV_ZOOM_MITCHELL; } else if (strcasecmp(name, "triangle") == 0) { filter = TCV_ZOOM_TRIANGLE; } else if (strcasecmp(name, "cubic_keys4") == 0) { filter = TCV_ZOOM_CUBIC_KEYS4; } else if (strcasecmp(name, "sinc8") == 0) { filter = TCV_ZOOM_SINC8; } else if (strcasecmp(name, "default") == 0) { filter = TCV_ZOOM_LANCZOS3; } else { filter = TCV_ZOOM_NULL; } return filter; } /*************************************************************************/ /*************************************************************************/ /** * *_filter: Filter functions for resizing. * * Parameters: * t: Filter parameter. * Return value: * Filter result. * Postconditions: 0 <= t && t <= 1 */ /************************************/ static const double hermite_support = 1.0; static double hermite_filter(double t) { /* f(t) = 2|t|^3 - 3|t|^2 + 1, -1 <= t <= 1 */ if (t < 0.0) t = -t; if (t < 1.0) return (2.0 * t - 3.0) * t * t + 1.0; return 0.0; } /************************************/ static const double box_support = 0.5; static double box_filter(double t) { if ((t > -0.5) && (t <= 0.5)) return 1.0; return 0.0; } /************************************/ static const double triangle_support = 1.0; static double triangle_filter(double t) { if (t < 0.0) t = -t; if (t < 1.0) return 1.0 - t; return 0.0; } /************************************/ static const double bell_support = 1.5; static double bell_filter(double t) { if (t < 0) t = -t; if (t < .5) return .75 - (t * t); if (t < 1.5) { t = (t - 1.5); return .5 * (t * t); } return 0.0; } /************************************/ static const double B_spline_support = 2.0; static double B_spline_filter(double t) { double tt; if (t < 0) t = -t; if (t < 1) { tt = t * t; return (.5 * tt * t) - tt + (2.0 / 3.0); } else if (t < 2) { t = 2 - t; return (1.0 / 6.0) * (t * t * t); } return 0.0; } /************************************/ static const double lanczos3_support = 3.0; #ifndef PI # define PI 3.14159265358979323846264338327950 #endif #define SINC(x) ((x) != 0 ? sin((x)*PI) / ((x)*PI) : 1.0) static double lanczos3_filter(double t) { if (t < 0) t = -t; if (t < 3.0) return SINC(t) * SINC(t/3.0); return 0.0; } #undef SINC /************************************/ static const double mitchell_support = 2.0; #define B (1.0 / 3.0) #define C (1.0 / 3.0) static double mitchell_filter(double t) { double tt; tt = t * t; if (t < 0) t = -t; if (t < 1.0) { t = (((12.0 - 9.0 * B - 6.0 * C) * (t * tt)) + ((-18.0 + 12.0 * B + 6.0 * C) * tt) + (6.0 - 2 * B)); return t / 6.0; } else if (t < 2.0) { t = (((-1.0 * B - 6.0 * C) * (t * tt)) + ((6.0 * B + 30.0 * C) * tt) + ((-12.0 * B - 48.0 * C) * t) + (8.0 * B + 24 * C)); return t / 6.0; } return 0.0; } #undef B #undef C /************************************/ /* Keys 4th-order Cubic */ static const double cubic_keys4_support = 3.0; static double cubic_keys4_filter(double t) { if (t < 0.0) t = -t; if (t < 1.0) return (3.0 + (t * t * (-7.0 + (t * 4.0)))) / 3.0; if (t < 2.0) return (30.0 + (t * (-59.0 + (t * (36.0 + (t * -7.0)))))) / 12.0; if (t < 3.0) return (-18.0 + (t * (21.0 + (t * (-8.0 + t))))) / 12.0; return 0.0; } /************************************/ /* Sinc with Lanczos window, 8 cycles */ static const double sinc8_support = 8.0; static double sinc8_filter(double t) { if (t < 0.0) t = -t; if (t == 0.0) { return 1.0; } else if (t < 8.0) { double w = sin(PI*t / 8.0) / (PI*t / 8.0); return w * sin(t*PI) / (t*PI); } else { return 0.0; } } /*************************************************************************/ /** * gen_contrib: Helper function to generate the list of contributors to * each resized pixel in one direction (horizontal or vertical). * * Parameters: * oldsize: Size of original image in the direction for which * contributors are being generated. * newsize: Size of resized image in the direction for which * contributors are being generated. * stride: Number of bytes between adjacent pixels in the direction * for which contributors are being generated. * filter: As for zoom_process(). * fwidth: As for zoom_process(). * Return value: * A pointer to a `newsize'-element array of `struct clist' elements, * or NULL on error (out of memory). * Preconditions: * oldsize > 0 * newsize > 0 * stride > 0 * filter != NULL * fwidth > 0 */ static struct clist *gen_contrib(int oldsize, int newsize, int stride, double (*filter)(double), double fwidth) { struct clist *contrib; double scale = (double)newsize / (double)oldsize; double new_fwidth, fscale; int i, j; contrib = tc_zalloc(newsize * sizeof(struct clist)); if (scale < 1.0) { fscale = 1.0 / scale; } else { fscale = 1.0; } new_fwidth = fwidth * fscale; for (i = 0; i < newsize; ++i) { double center = (double) i / scale; int left = ceil(center - new_fwidth); int right = floor(center + new_fwidth); contrib[i].n = 0; contrib[i].list = tc_zalloc((right-left+1) * sizeof(struct contrib)); for (j = left; j <= right; ++j) { int k, n; double weight = center - (double) j; weight = (*filter)(weight / fscale) / fscale; if (j < 0) { n = -j; } else if (j >= oldsize) { n = (oldsize - j) + oldsize - 1; } else { n = j; } k = contrib[i].n++; contrib[i].list[k].pixel = n*stride; contrib[i].list[k].weight = weight; } } return contrib; } /*************************************************************************/ /*************************************************************************/ /* External interface. */ /*************************************************************************/ /** * zoom_init: Allocate, initialize, and return a ZoomInfo structure for * use in subsequent zoom_process() calls. The structure should be freed * with zoom_free() when no longer needed. * * Parameters: * old_w: Width of original image. * old_h: Height of original image. * new_w: Width of resized image. * new_h: Height of resized image. * Bpp: Bytes (not bits!) per pixel. * old_stride: Bytes per line of original image. * new_stride: Bytes per line of resized image. * filter: Filter identifier (TCV_ZOOM_*). * Return value: * A pointer to a newly allocated ZoomInfo structure, or NULL on error * (invalid parameters or out of memory). */ ZoomInfo *zoom_init(int old_w, int old_h, int new_w, int new_h, int Bpp, int old_stride, int new_stride, TCVZoomFilter filter) { ZoomInfo *zi; struct clist *x_contrib = NULL, *y_contrib = NULL; /* Sanity check */ if (old_w <= 0 || old_h <= 0 || new_w <= 0 || new_h <= 0 || Bpp <= 0 || old_stride <= 0 || new_stride <= 0) return NULL; /* Allocate structure */ zi = tc_malloc(sizeof(*zi)); if (!zi) return NULL; /* Set up scalar members, and check filter value */ zi->old_w = old_w; zi->old_h = old_h; zi->new_w = new_w; zi->new_h = new_h; zi->Bpp = Bpp; zi->old_stride = old_stride; zi->new_stride = new_stride; switch (filter) { case TCV_ZOOM_BOX: zi->filter = box_filter; zi->fwidth = box_support; break; case TCV_ZOOM_TRIANGLE: zi->filter = triangle_filter; zi->fwidth = triangle_support; break; case TCV_ZOOM_HERMITE: zi->filter = hermite_filter; zi->fwidth = hermite_support; break; case TCV_ZOOM_BELL: zi->filter = bell_filter; zi->fwidth = bell_support; break; case TCV_ZOOM_B_SPLINE: zi->filter = B_spline_filter; zi->fwidth = B_spline_support; break; case TCV_ZOOM_MITCHELL: zi->filter = mitchell_filter; zi->fwidth = mitchell_support; break; case TCV_ZOOM_LANCZOS3: zi->filter = lanczos3_filter; zi->fwidth = lanczos3_support; break; case TCV_ZOOM_CUBIC_KEYS4: zi->filter = cubic_keys4_filter; zi->fwidth = cubic_keys4_support; break; case TCV_ZOOM_SINC8: zi->filter = sinc8_filter; zi->fwidth = sinc8_support; break; default: free(zi); return NULL; } /* Generate contributor lists and allocate temporary image buffer */ zi->x_contrib = NULL; zi->y_contrib = NULL; zi->tmpimage = tc_malloc(new_w * old_h * Bpp); if (!zi->tmpimage) goto error_out; if (old_w != new_w) { x_contrib = gen_contrib(old_w, new_w, Bpp, zi->filter, zi->fwidth); if (!x_contrib) goto error_out; } if (old_h != new_h) { /* Calculate the correct stride--if the width isn't changing, * this will just be old_stride */ int stride = (old_w==new_w) ? old_stride : Bpp*new_w; y_contrib = gen_contrib(old_h, new_h, stride, zi->filter, zi->fwidth); if (!y_contrib) goto error_out; } /* Convert contributor lists into flat arrays and fixed-point values. * The flat array consists of a contributor count plus two values per * contributor (index and fixed-point weight) for each output pixel. * Note that for the horizontal direction, we make `Bpp' copies of the * contributors, adjusting the offset for each byte of the pixel. */ if (x_contrib) { int count = 0, i; int32_t *ptr; for (i = 0; i < new_w; i++) count += 1 + 2 * x_contrib[i].n; zi->x_contrib = tc_malloc(sizeof(int32_t) * count * Bpp); if (!zi->x_contrib) goto error_out; for (ptr = zi->x_contrib, i = 0; i < new_w * Bpp; i++) { int j; *ptr++ = x_contrib[i/Bpp].n; for (j = 0; j < x_contrib[i/Bpp].n; j++) { *ptr++ = x_contrib[i/Bpp].list[j].pixel + i%Bpp; *ptr++ = DOUBLE_TO_FIXED(x_contrib[i/Bpp].list[j].weight); } } /* Free original contributor list */ for (i = 0; i < new_w; i++) free(x_contrib[i].list); free(x_contrib); x_contrib = NULL; } if (y_contrib) { int count = 0, i; int32_t *ptr; for (i = 0; i < new_h; i++) count += 1 + 2 * y_contrib[i].n; zi->y_contrib = tc_malloc(sizeof(int32_t) * count); if (!zi->y_contrib) goto error_out; for (ptr = zi->y_contrib, i = 0; i < new_h; i++) { int j; *ptr++ = y_contrib[i].n; for (j = 0; j < y_contrib[i].n; j++) { *ptr++ = y_contrib[i].list[j].pixel; *ptr++ = DOUBLE_TO_FIXED(y_contrib[i].list[j].weight); } } for (i = 0; i < new_h; i++) free(y_contrib[i].list); free(y_contrib); y_contrib = NULL; } /* Done */ return zi; error_out: { if (x_contrib) { int i; for (i = 0; i < new_w; i++) free(x_contrib[i].list); free(x_contrib); } if (y_contrib) { int i; for (i = 0; i < new_w; i++) free(x_contrib[i].list); free(x_contrib); } zoom_free(zi); return NULL; } } /*************************************************************************/ /** * zoom_process: Image resizing core. * * Parameters: * zi: ZoomInfo structure allocated by zoom_init(). * src: Source data plane. * dest: Destination data plane. * Return value: None. * Preconditions: * zi was allocated by zoom_init() * src != NULL * dest != NULL * src and dest do not overlap */ /* clamp the input to the specified range */ #define CLAMP(v,l,h) ((v)<(l) ? (l) : (v) > (h) ? (h) : (v)) void zoom_process(const ZoomInfo *zi, const uint8_t *src, uint8_t *dest) { int from_stride, to_stride; const uint8_t *from; uint8_t *to; from = src; from_stride = zi->old_stride; /* Apply filter to zoom horizontally from src to tmp (if necessary) */ if (zi->x_contrib) { int y; to = zi->tmpimage; to_stride = zi->new_w * zi->Bpp; for (y = 0; y < zi->old_h; y++, from += from_stride, to += to_stride) { int32_t *contrib = zi->x_contrib; int x; for (x = 0; x < zi->new_w * zi->Bpp; x++) { int32_t weight = DOUBLE_TO_FIXED(0.5); int n = *contrib++, i; for (i = 0; i < n; i++) { int pixel = *contrib++; weight += from[pixel] * (*contrib++); } to[x] = CLAMP(FIXED_TO_INT(weight), 0, 255); } } from = zi->tmpimage; from_stride = to_stride; } /* Apply filter to zoom vertically from tmp (or src) to dest */ /* Use Y as the outside loop to avoid cache thrashing on output buffer */ to = dest; to_stride = zi->new_stride; if (zi->y_contrib) { int32_t *contrib = zi->y_contrib; int y; for (y = 0; y < zi->new_h; y++, to += to_stride) { int n = *contrib++, x; for (x = 0; x < zi->new_w * zi->Bpp; x++) { int32_t weight = DOUBLE_TO_FIXED(0.5); int i; for (i = 0; i < n; i++) { int pixel = contrib[i*2]; weight += from[x+pixel] * contrib[i*2+1]; } to[x] = CLAMP(FIXED_TO_INT(weight), 0, 255); } contrib += 2*n; } } else { /* No zooming necessary, just copy */ if (from_stride == zi->new_w*zi->Bpp && to_stride == zi->new_w*zi->Bpp ) { /* We can copy the whole frame at once */ ac_memcpy(to, from, to_stride * zi->new_h); } else { /* Copy one row at a time */ int y; for (y = 0; y < zi->new_h; y++) { ac_memcpy(to + y*to_stride, from + y*from_stride, zi->new_w * zi->Bpp); } } } } /*************************************************************************/ /** * zoom_free(): Free a ZoomInfo structure. * * Parameters: * zi: ZoomInfo structure allocated by zoom_init(). * Return value: * None. * Preconditions: * zi was allocated by zoom_init() * Postconditions: * zi is freed */ void zoom_free(ZoomInfo *zi) { free(zi->x_contrib); free(zi->y_contrib); free(zi->tmpimage); free(zi); } /*************************************************************************/ /* * Local variables: * c-file-style: "stroustrup" * c-file-offsets: ((case-label . *) (statement-case-intro . *)) * indent-tabs-mode: nil * End: * * vim: expandtab shiftwidth=4: */