libwebp/src/enc/picture.c
Pascal Massimino 416b7a6b95 raise the fixed-point precision for the rescaler
for super-large upscaling factor (32x and up), 20bits was not enough.

Change-Id: I7b0d1975d0609948d464cfc3aeff1a70df16dc57
2011-05-16 17:12:37 -07:00

651 lines
20 KiB
C

// Copyright 2011 Google Inc.
//
// This code is licensed under the same terms as WebM:
// Software License Agreement: http://www.webmproject.org/license/software/
// Additional IP Rights Grant: http://www.webmproject.org/license/additional/
// -----------------------------------------------------------------------------
//
// WebPPicture utils: colorspace conversion, crop, ...
//
// Author: Skal (pascal.massimino@gmail.com)
#include <assert.h>
#include <stdlib.h>
#include "vp8enci.h"
#if defined(__cplusplus) || defined(c_plusplus)
extern "C" {
#endif
//-----------------------------------------------------------------------------
// WebPPicture
//-----------------------------------------------------------------------------
int WebPPictureAlloc(WebPPicture* const picture) {
if (picture) {
const WebPEncCSP uv_csp = picture->colorspace & WEBP_CSP_UV_MASK;
const int has_alpha = picture->colorspace & WEBP_CSP_ALPHA_BIT;
const int width = picture->width;
const int height = picture->height;
const int y_stride = width;
const int uv_width = (width + 1) / 2;
const int uv_height = (height + 1) / 2;
const int uv_stride = uv_width;
int uv0_stride = 0;
int a_width, a_stride;
uint64_t y_size, uv_size, uv0_size, a_size, total_size;
uint8_t* mem;
// U/V
switch (uv_csp) {
case WEBP_YUV420:
break;
#ifdef WEBP_EXPERIMENTAL_FEATURES
case WEBP_YUV400: // for now, we'll just reset the U/V samples
break;
case WEBP_YUV422:
uv0_stride = uv_width;
break;
case WEBP_YUV444:
uv0_stride = width;
break;
#endif
default:
return 0;
}
uv0_size = height * uv0_stride;
// alpha
a_width = has_alpha ? width : 0;
a_stride = a_width;
y_size = (uint64_t)y_stride * height;
uv_size = (uint64_t)uv_stride * uv_height;
a_size = (uint64_t)a_stride * height;
total_size = y_size + a_size + 2 * uv_size + 2 * uv0_size;
// Security and validation checks
if (width <= 0 || height <= 0 || // check for luma/alpha param error
uv_width < 0 || uv_height < 0 || // check for u/v param error
y_size >= (1ULL << 40) || // check for reasonable global size
(size_t)total_size != total_size) { // check for overflow on 32bit
return 0;
}
picture->y_stride = y_stride;
picture->uv_stride = uv_stride;
picture->a_stride = a_stride;
picture->uv0_stride = uv0_stride;
WebPPictureFree(picture); // erase previous buffer
mem = (uint8_t*)malloc((size_t)total_size);
if (mem == NULL) return 0;
picture->y = mem;
mem += y_size;
picture->u = mem;
mem += uv_size;
picture->v = mem;
mem += uv_size;
if (a_size) {
picture->a = mem;
mem += a_size;
}
if (uv0_size) {
picture->u0 = mem;
mem += uv0_size;
picture->v0 = mem;
mem += uv0_size;
}
}
return 1;
}
// Grab the 'specs' (writer, *opaque, width, height...) from 'src' and copy them
// into 'dst'. Mark 'dst' as not owning any memory. 'src' can be NULL.
static void WebPPictureGrabSpecs(const WebPPicture* const src,
WebPPicture* const dst) {
if (src) *dst = *src;
dst->y = dst->u = dst->v = NULL;
dst->u0 = dst->v0 = NULL;
dst->a = NULL;
}
// Release memory owned by 'picture'.
void WebPPictureFree(WebPPicture* const picture) {
if (picture) {
free(picture->y);
WebPPictureGrabSpecs(NULL, picture);
}
}
//-----------------------------------------------------------------------------
// Picture copying
int WebPPictureCopy(const WebPPicture* const src, WebPPicture* const dst) {
int y;
if (src == NULL || dst == NULL) return 0;
if (src == dst) return 1;
WebPPictureGrabSpecs(src, dst);
if (!WebPPictureAlloc(dst)) return 0;
for (y = 0; y < dst->height; ++y) {
memcpy(dst->y + y * dst->y_stride,
src->y + y * src->y_stride, src->width);
}
for (y = 0; y < (dst->height + 1) / 2; ++y) {
memcpy(dst->u + y * dst->uv_stride,
src->u + y * src->uv_stride, (src->width + 1) / 2);
memcpy(dst->v + y * dst->uv_stride,
src->v + y * src->uv_stride, (src->width + 1) / 2);
}
#ifdef WEBP_EXPERIMENTAL_FEATURES
if (dst->a != NULL) {
for (y = 0; y < dst->height; ++y) {
memcpy(dst->a + y * dst->a_stride,
src->a + y * src->a_stride, src->width);
}
}
if (dst->u0 != NULL) {
int uv0_width = src->width;
if ((dst->colorspace & WEBP_CSP_UV_MASK) == WEBP_YUV422) {
uv0_width = (uv0_width + 1) / 2;
}
for (y = 0; y < dst->height; ++y) {
memcpy(dst->u0 + y * dst->uv0_stride,
src->u0 + y * src->uv0_stride, uv0_width);
memcpy(dst->v0 + y * dst->uv0_stride,
src->v0 + y * src->uv0_stride, uv0_width);
}
}
#endif
return 1;
}
//-----------------------------------------------------------------------------
// Picture cropping
int WebPPictureCrop(WebPPicture* const pic,
int left, int top, int width, int height) {
WebPPicture tmp;
int y;
if (pic == NULL) return 0;
if (width <= 0 || height <= 0) return 0;
if (left < 0 || ((left + width + 1) & ~1) > pic->width) return 0;
if (top < 0 || ((top + height + 1) & ~1) > pic->height) return 0;
WebPPictureGrabSpecs(pic, &tmp);
tmp.width = width;
tmp.height = height;
if (!WebPPictureAlloc(&tmp)) return 0;
for (y = 0; y < height; ++y) {
memcpy(tmp.y + y * tmp.y_stride,
pic->y + (top + y) * pic->y_stride + left, width);
}
for (y = 0; y < (height + 1) / 2; ++y) {
const int offset = (y + top / 2) * pic->uv_stride + left / 2;
memcpy(tmp.u + y * tmp.uv_stride, pic->u + offset, (width + 1) / 2);
memcpy(tmp.v + y * tmp.uv_stride, pic->v + offset, (width + 1) / 2);
}
#ifdef WEBP_EXPERIMENTAL_FEATURES
if (tmp.a) {
for (y = 0; y < height; ++y) {
memcpy(tmp.a + y * tmp.a_stride,
pic->a + (top + y) * pic->a_stride + left, width);
}
}
if (tmp.u0) {
int w = width;
int l = left;
if (tmp.colorspace == WEBP_YUV422) {
w = (w + 1) / 2;
l = (l + 1) / 2;
}
for (y = 0; y < height; ++y) {
memcpy(tmp.u0 + y * tmp.uv0_stride,
pic->u0 + (top + y) * pic->uv0_stride + l, w);
memcpy(tmp.v0 + y * tmp.uv0_stride,
pic->v0 + (top + y) * pic->uv0_stride + l, w);
}
}
#endif
WebPPictureFree(pic);
*pic = tmp;
return 1;
}
//-----------------------------------------------------------------------------
// Simple picture rescaler
#define RFIX 30
#define MULT(x,y) (((int64_t)(x) * (y) + (1 << (RFIX - 1))) >> RFIX)
static inline void ImportRow(const uint8_t* src, int src_width,
int32_t* frow, int32_t* irow, int dst_width) {
const int x_expand = (src_width < dst_width);
const int fx_scale = (1 << RFIX) / dst_width;
int x_in = 0;
int x_out;
int x_accum = 0;
if (!x_expand) {
int sum = 0;
for (x_out = 0; x_out < dst_width; ++x_out) {
x_accum += src_width - dst_width;
for (; x_accum > 0; x_accum -= dst_width) {
sum += src[x_in++];
}
{ // Emit next horizontal pixel.
const int32_t base = src[x_in++];
const int32_t frac = base * (-x_accum);
frow[x_out] = (sum + base) * dst_width - frac;
sum = MULT(frac, fx_scale); // fresh fractional start for next pixel
}
}
} else { // simple bilinear interpolation
int left = src[0], right = src[0];
for (x_out = 0; x_out < dst_width; ++x_out) {
if (x_accum < 0) {
left = right;
right = src[++x_in];
x_accum += dst_width - 1;
}
frow[x_out] = right * (dst_width - 1) + (left - right) * x_accum;
x_accum -= src_width - 1;
}
}
// Accumulate the new row's contribution
for (x_out = 0; x_out < dst_width; ++x_out) {
irow[x_out] += frow[x_out];
}
}
static void ExportRow(int32_t* frow, int32_t* irow, uint8_t* dst, int dst_width,
const int yscale, const int64_t fxy_scale) {
int x_out;
for (x_out = 0; x_out < dst_width; ++x_out) {
const int frac = MULT(frow[x_out], yscale);
const int v = MULT(irow[x_out] - frac, fxy_scale);
dst[x_out] = (!(v & ~0xff)) ? v : (v < 0) ? 0 : 255;
irow[x_out] = frac; // new fractional start
}
}
static void RescalePlane(const uint8_t* src,
int src_width, int src_height, int src_stride,
uint8_t* dst,
int dst_width, int dst_height, int dst_stride,
int32_t* const work) {
const int x_expand = (src_width < dst_width);
const int fy_scale = (1 << RFIX) / dst_height;
const int64_t fxy_scale = x_expand ?
((int64_t)dst_height << RFIX) / (dst_width * src_height) :
((int64_t)dst_height << RFIX) / (src_width * src_height);
int y_accum = src_height;
int y;
int32_t* irow = work; // integral contribution
int32_t* frow = work + dst_width; // fractional contribution
memset(work, 0, 2 * dst_width * sizeof(*work));
for (y = 0; y < src_height; ++y) {
// import new contribution of one source row.
ImportRow(src, src_width, frow, irow, dst_width);
src += src_stride;
// emit output row(s)
y_accum -= dst_height;
for (; y_accum <= 0; y_accum += src_height) {
const int yscale = fy_scale * (-y_accum);
ExportRow(frow, irow, dst, dst_width, yscale, fxy_scale);
dst += dst_stride;
}
}
}
#undef MULT
#undef RFIX
int WebPPictureRescale(WebPPicture* const pic, int width, int height) {
WebPPicture tmp;
int prev_width, prev_height;
int32_t* work;
if (pic == NULL) return 0;
prev_width = pic->width;
prev_height = pic->height;
// if width is unspecified, scale original proportionally to height ratio.
if (width == 0) {
width = (prev_width * height + prev_height / 2) / prev_height;
}
// if height is unspecified, scale original proportionally to width ratio.
if (height == 0) {
height = (prev_height * width + prev_width / 2) / prev_width;
}
// Check if the overall dimensions still make sense.
if (width <= 0 || height <= 0) return 0;
WebPPictureGrabSpecs(pic, &tmp);
tmp.width = width;
tmp.height = height;
if (!WebPPictureAlloc(&tmp)) return 0;
work = malloc(2 * width * sizeof(int32_t));
if (work == NULL) {
WebPPictureFree(&tmp);
return 0;
}
RescalePlane(pic->y, prev_width, prev_height, pic->y_stride,
tmp.y, width, height, tmp.y_stride, work);
RescalePlane(pic->u,
(prev_width + 1) / 2, (prev_height + 1) / 2, pic->uv_stride,
tmp.u,
(width + 1) / 2, (height + 1) / 2, tmp.uv_stride, work);
RescalePlane(pic->v,
(prev_width + 1) / 2, (prev_height + 1) / 2, pic->uv_stride,
tmp.v,
(width + 1) / 2, (height + 1) / 2, tmp.uv_stride, work);
#ifdef WEBP_EXPERIMENTAL_FEATURES
if (tmp.a) {
RescalePlane(pic->a, prev_width, prev_height, pic->a_stride,
tmp.a, width, height, tmp.a_stride, work);
}
if (tmp.u0) {
int s = 1;
if ((tmp.colorspace & WEBP_CSP_UV_MASK) == WEBP_YUV422) {
s = 2;
}
RescalePlane(
pic->u0, (prev_width + s / 2) / s, prev_height, pic->uv0_stride,
tmp.u0, (width + s / 2) / s, height, tmp.uv0_stride, work);
RescalePlane(
pic->v0, (prev_width + s / 2) / s, prev_height, pic->uv0_stride,
tmp.v0, (width + s / 2) / s, height, tmp.uv0_stride, work);
}
#endif
WebPPictureFree(pic);
free(work);
*pic = tmp;
return 1;
}
//-----------------------------------------------------------------------------
// Write-to-memory
typedef struct {
uint8_t** mem;
size_t max_size;
size_t* size;
} WebPMemoryWriter;
static void InitMemoryWriter(WebPMemoryWriter* const writer) {
*writer->mem = NULL;
*writer->size = 0;
writer->max_size = 0;
}
static int WebPMemoryWrite(const uint8_t* data, size_t data_size,
const WebPPicture* const picture) {
WebPMemoryWriter* const w = (WebPMemoryWriter*)picture->custom_ptr;
size_t next_size;
if (w == NULL) {
return 1;
}
next_size = (*w->size) + data_size;
if (next_size > w->max_size) {
uint8_t* new_mem;
size_t next_max_size = w->max_size * 2;
if (next_max_size < next_size) next_max_size = next_size;
if (next_max_size < 8192) next_max_size = 8192;
new_mem = (uint8_t*)malloc(next_max_size);
if (new_mem == NULL) {
return 0;
}
if ((*w->size) > 0) {
memcpy(new_mem, *w->mem, *w->size);
}
free(*w->mem);
*w->mem = new_mem;
w->max_size = next_max_size;
}
if (data_size) {
memcpy((*w->mem) + (*w->size), data, data_size);
*w->size += data_size;
}
return 1;
}
//-----------------------------------------------------------------------------
// RGB -> YUV conversion
// The exact naming is Y'CbCr, following the ITU-R BT.601 standard.
// More information at: http://en.wikipedia.org/wiki/YCbCr
// Y = 0.2569 * R + 0.5044 * G + 0.0979 * B + 16
// U = -0.1483 * R - 0.2911 * G + 0.4394 * B + 128
// V = 0.4394 * R - 0.3679 * G - 0.0715 * B + 128
// We use 16bit fixed point operations.
enum { YUV_FRAC = 16 };
static inline int clip_uv(int v) {
v = (v + (257 << (YUV_FRAC + 2 - 1))) >> (YUV_FRAC + 2);
return ((v & ~0xff) == 0) ? v : (v < 0) ? 0 : 255;
}
static inline int rgb_to_y(int r, int g, int b) {
const int kRound = (1 << (YUV_FRAC - 1)) + (16 << YUV_FRAC);
const int luma = 16839 * r + 33059 * g + 6420 * b;
return (luma + kRound) >> YUV_FRAC; // no need to clip
}
static inline int rgb_to_u(int r, int g, int b) {
return clip_uv(-9719 * r - 19081 * g + 28800 * b);
}
static inline int rgb_to_v(int r, int g, int b) {
return clip_uv(+28800 * r - 24116 * g - 4684 * b);
}
// TODO: we can do better than simply 2x2 averaging on U/V samples.
#define SUM4(ptr) ((ptr)[0] + (ptr)[step] + \
(ptr)[rgb_stride] + (ptr)[rgb_stride + step])
#define SUM2H(ptr) (2 * (ptr)[0] + 2 * (ptr)[step])
#define SUM2V(ptr) (2 * (ptr)[0] + 2 * (ptr)[rgb_stride])
#define SUM1(ptr) (4 * (ptr)[0])
#define RGB_TO_UV(x, y, SUM) { \
const int src = (2 * (step * (x) + (y) * rgb_stride)); \
const int dst = (x) + (y) * picture->uv_stride; \
const int r = SUM(r_ptr + src); \
const int g = SUM(g_ptr + src); \
const int b = SUM(b_ptr + src); \
picture->u[dst] = rgb_to_u(r, g, b); \
picture->v[dst] = rgb_to_v(r, g, b); \
}
#define RGB_TO_UV0(x_in, x_out, y, SUM) { \
const int src = (step * (x_in) + (y) * rgb_stride); \
const int dst = (x_out) + (y) * picture->uv0_stride; \
const int r = SUM(r_ptr + src); \
const int g = SUM(g_ptr + src); \
const int b = SUM(b_ptr + src); \
picture->u0[dst] = rgb_to_u(r, g, b); \
picture->v0[dst] = rgb_to_v(r, g, b); \
}
static void MakeGray(WebPPicture* const picture) {
int y;
const int uv_width = (picture->width + 1) >> 1;
for (y = 0; y < ((picture->height + 1) >> 1); ++y) {
memset(picture->u + y * picture->uv_stride, 128, uv_width);
memset(picture->v + y * picture->uv_stride, 128, uv_width);
}
}
static int Import(WebPPicture* const picture,
const uint8_t* const rgb, int rgb_stride,
int step, int swap_rb, int import_alpha) {
const WebPEncCSP uv_csp = picture->colorspace & WEBP_CSP_UV_MASK;
int x, y;
const uint8_t* const r_ptr = rgb + (swap_rb ? 2 : 0);
const uint8_t* const g_ptr = rgb + 1;
const uint8_t* const b_ptr = rgb + (swap_rb ? 0 : 2);
const int width = picture->width;
const int height = picture->height;
// Import luma plane
for (y = 0; y < height; ++y) {
for (x = 0; x < width; ++x) {
const int offset = step * x + y * rgb_stride;
picture->y[x + y * picture->y_stride] =
rgb_to_y(r_ptr[offset], g_ptr[offset], b_ptr[offset]);
}
}
// Downsample U/V plane
if (uv_csp != WEBP_YUV400) {
for (y = 0; y < (height >> 1); ++y) {
for (x = 0; x < (width >> 1); ++x) {
RGB_TO_UV(x, y, SUM4);
}
if (picture->width & 1) {
RGB_TO_UV(x, y, SUM2V);
}
}
if (height & 1) {
for (x = 0; x < (width >> 1); ++x) {
RGB_TO_UV(x, y, SUM2H);
}
if (width & 1) {
RGB_TO_UV(x, y, SUM1);
}
}
#ifdef WEBP_EXPERIMENTAL_FEATURES
// Store original U/V samples too
if (uv_csp == WEBP_YUV422) {
for (y = 0; y < height; ++y) {
for (x = 0; x < (width >> 1); ++x) {
RGB_TO_UV0(2 * x, x, y, SUM2H);
}
if (width & 1) {
RGB_TO_UV0(2 * x, x, y, SUM1);
}
}
} else if (uv_csp == WEBP_YUV444) {
for (y = 0; y < height; ++y) {
for (x = 0; x < width; ++x) {
RGB_TO_UV0(x, x, y, SUM1);
}
}
}
#endif
} else {
MakeGray(picture);
}
if (import_alpha) {
#ifdef WEBP_EXPERIMENTAL_FEATURES
const uint8_t* const a_ptr = rgb + 3;
assert(step >= 4);
for (y = 0; y < height; ++y) {
for (x = 0; x < width; ++x) {
picture->a[x + y * picture->a_stride] =
a_ptr[step * x + y * rgb_stride];
}
}
#endif
}
return 1;
}
#undef SUM4
#undef SUM2V
#undef SUM2H
#undef SUM1
#undef RGB_TO_UV
int WebPPictureImportRGB(WebPPicture* const picture,
const uint8_t* const rgb, int rgb_stride) {
picture->colorspace &= ~WEBP_CSP_ALPHA_BIT;
if (!WebPPictureAlloc(picture)) return 0;
return Import(picture, rgb, rgb_stride, 3, 0, 0);
}
int WebPPictureImportBGR(WebPPicture* const picture,
const uint8_t* const rgb, int rgb_stride) {
picture->colorspace &= ~WEBP_CSP_ALPHA_BIT;
if (!WebPPictureAlloc(picture)) return 0;
return Import(picture, rgb, rgb_stride, 3, 1, 0);
}
int WebPPictureImportRGBA(WebPPicture* const picture,
const uint8_t* const rgba, int rgba_stride) {
picture->colorspace |= WEBP_CSP_ALPHA_BIT;
if (!WebPPictureAlloc(picture)) return 0;
return Import(picture, rgba, rgba_stride, 4, 0, 1);
}
int WebPPictureImportBGRA(WebPPicture* const picture,
const uint8_t* const rgba, int rgba_stride) {
picture->colorspace |= WEBP_CSP_ALPHA_BIT;
if (!WebPPictureAlloc(picture)) return 0;
return Import(picture, rgba, rgba_stride, 4, 1, 1);
}
//-----------------------------------------------------------------------------
// Simplest call:
typedef int (*Importer)(WebPPicture* const, const uint8_t* const, int);
static size_t Encode(const uint8_t* rgba, int width, int height, int stride,
Importer import, float quality_factor, uint8_t** output) {
size_t output_size = 0;
WebPPicture pic;
WebPConfig config;
WebPMemoryWriter wrt;
int ok;
if (!WebPConfigPreset(&config, WEBP_PRESET_DEFAULT, quality_factor) ||
!WebPPictureInit(&pic)) {
return 0; // shouldn't happen, except if system installation is broken
}
pic.width = width;
pic.height = height;
pic.writer = WebPMemoryWrite;
pic.custom_ptr = &wrt;
wrt.mem = output;
wrt.size = &output_size;
InitMemoryWriter(&wrt);
ok = import(&pic, rgba, stride) && WebPEncode(&config, &pic);
WebPPictureFree(&pic);
if (!ok) {
free(*output);
*output = NULL;
return 0;
}
return output_size;
}
#define ENCODE_FUNC(NAME, IMPORTER) \
size_t NAME(const uint8_t* in, int w, int h, int bps, float q, \
uint8_t** out) { \
return Encode(in, w, h, bps, IMPORTER, q, out); \
}
ENCODE_FUNC(WebPEncodeRGB, WebPPictureImportRGB);
ENCODE_FUNC(WebPEncodeBGR, WebPPictureImportBGR);
ENCODE_FUNC(WebPEncodeRGBA, WebPPictureImportRGBA);
ENCODE_FUNC(WebPEncodeBGRA, WebPPictureImportBGRA);
#undef ENCODE_FUNC
//-----------------------------------------------------------------------------
#if defined(__cplusplus) || defined(c_plusplus)
} // extern "C"
#endif