3D Lut 电影级调色算法 附完整C代码

在前面的文章,我提到过VSCO Cam 的胶片滤镜算法实现是3d lut。

 那么3d lut  到底是个什么东西呢?

或者说它是用来做什么的?

长话短说,3d lut(全称 : 3D Lookup table )它是通过建立一个颜色映射表,对图像的色调进行重调的算法。

有用于摄像机的效果美化润色,例如一些所谓的数码相机之类的。

也有用于影视后期调色,渲染影视作品的颜色基调等等。

简单的说,你想要把图片上的一些颜色通过你自己的预设给替换掉。

例如红色换成白色,白色换成绿色。

当然这在现实中操作起来非常复杂。

因为 RGB888(8+8+8=24位色):

(2^8)*(2^8)*(2^8)=

256*256*256=16777216

有16M 种颜色,如果采用手工操作的方式一个一个颜色地换,那人还活不活了。

所以就有通过建立映射表进行插值达到逼近这种效果的算法。

它就是3d lut,当然也有2d lut,1d lut。

精度不一,效果不一。

例如:

调节亮度 可以认为是1d lut.

调节对比度 可以认为是 2d lut.

而调节整体的色调最佳肯定是3d lut.

当然2d lut 也是可以做到,但是精度就没有那么高了。

我之前也提到过,市面有不少app是采用2d LUT,毕竟精度不需要那么高。

2d够用了。

但是在摄影界,影视后期这一行当里,3d lut是标配。

相关资料可以参阅:

3D LUT调色:单反如何实现电影级调色。

 在VSCO Cam APP中滤镜效果每一档都是一个17*17*17的3d lut预设。

先上个图,大家感受一下。

只是一个例子,效果是看做预设的功底的。

那么3d lut 的实现具体是什么算法呢?

Nearest_interpolation

Trilinear_interpolation

Tetrahedral interpolation

 当然据我所知,Trilinear_interpolation 是用得最广泛的一种。

之前做APP滤镜的时候,调研过不少资料。

但是当时发现一些开源项目的实现是有问题的,插值算错坐标之类的。

有一次心血来潮,去翻了翻FFmpeg的代码,居然发现了它也有实现3d lut算法。

嗯,站在巨人的肩膀上。

抽了点时间对FFmpeg中的3d lut 进行了整理。

提取出它的算法,并编写示例。

当然未经过严格验证,应该存在一些小Bugs。

完整示例代码献上:

/*
 * Copyright (c) 2013 Clément Bœsch
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */
/**
 * 3D Lookup table filter
 */
#include "browse.h"

#define USE_SHELL_OPEN

#define STB_IMAGE_STATIC
#define STB_IMAGE_IMPLEMENTATION

#include "stb_image.h"
/* ref:https://github.com/nothings/stb/blob/master/stb_image.h */
#define TJE_IMPLEMENTATION

#include "tiny_jpeg.h"
/* ref:https://github.com/serge-rgb/TinyJPEG/blob/master/tiny_jpeg.h */
#include <math.h>
#include <stdbool.h>
#include <stdio.h>
#include "timing.h"
#include <stdint.h>
#include <assert.h>

#ifndef _MAX_DRIVE
#define _MAX_DRIVE 3
#endif
#ifndef _MAX_FNAME
#define _MAX_FNAME 256
#endif
#ifndef _MAX_EXT
#define _MAX_EXT 256
#endif
#ifndef _MAX_DIR
#define _MAX_DIR 256
#endif
#ifdef _MSC_VER
#endif
#ifndef MIN
#define MIN(a, b)    ( (a) > (b) ? (b) : (a) )
#endif
#ifndef _NEAR
#define _NEAR(x)    ( (int) ( (x) + .5) )
#endif
#ifndef PREV
#define PREV(x)    ( (int) (x) )
#endif
#ifndef NEXT
#define NEXT(x)    (MIN( (int) (x) + 1, lut3d->lutsize - 1 ) )
#endif
#ifndef R
#define R    0
#endif
#ifndef G
#define G    1
#endif
#ifndef B
#define B    2
#endif
#ifndef A
#define A    3
#endif
#ifndef MAX_LEVEL
#define MAX_LEVEL 64
#endif

enum interp_mode {
    INTERPOLATE_NEAREST,
    INTERPOLATE_TRILINEAR,
    INTERPOLATE_TETRAHEDRAL,
    NB_INTERP_MODE
};

struct rgbvec {
    float r, g, b;
};


/* 3D LUT don't often go up to level 32 */


typedef struct LUT3DContext {
    uint8_t rgba_map[4];
    int step;
    struct rgbvec lut[MAX_LEVEL][MAX_LEVEL][MAX_LEVEL];
    int lutsize;
} LUT3DContext;
#ifdef _MSC_VER
int strcasecmp(const char *s1, char *s2) {
    while (toupper((unsigned char)*s1) == toupper((unsigned char)*s2++))
        if (*s1++ == 0x00)
            return (0);
    return (toupper((unsigned char)*s1) - toupper((unsigned char) *--s2));
}
#endif

static inline float lerpf(float v0, float v1, float f) {
    return (v0 + (v1 - v0) * f);
}

static inline struct rgbvec lerp(const struct rgbvec *v0, const struct rgbvec *v1, float f) {
    struct rgbvec v = {
            lerpf(v0->r, v1->r, f), lerpf(v0->g, v1->g, f), lerpf(v0->b, v1->b, f)
    };
    return (v);
}


/**
 * Get the nearest defined point
 */
static inline struct rgbvec interp_nearest(const LUT3DContext *lut3d,
                                           const struct rgbvec *s) {
    return (lut3d->lut[_NEAR(s->r)][_NEAR(s->g)][_NEAR(s->b)]);
}


/**
 * Interpolate using the 8 vertices of a cube
 * @see https://en.wikipedia.org/wiki/Trilinear_interpolation
 */
static inline struct rgbvec interp_trilinear(const LUT3DContext *lut3d,
                                             const struct rgbvec *s) {
    const int prev[] = {PREV(s->r), PREV(s->g), PREV(s->b)};
    const int next[] = {NEXT(s->r), NEXT(s->g), NEXT(s->b)};
    const struct rgbvec d = {s->r - prev[0], s->g - prev[1], s->b - prev[2]};
    const struct rgbvec c000 = lut3d->lut[prev[0]][prev[1]][prev[2]];
    const struct rgbvec c001 = lut3d->lut[prev[0]][prev[1]][next[2]];
    const struct rgbvec c010 = lut3d->lut[prev[0]][next[1]][prev[2]];
    const struct rgbvec c011 = lut3d->lut[prev[0]][next[1]][next[2]];
    const struct rgbvec c100 = lut3d->lut[next[0]][prev[1]][prev[2]];
    const struct rgbvec c101 = lut3d->lut[next[0]][prev[1]][next[2]];
    const struct rgbvec c110 = lut3d->lut[next[0]][next[1]][prev[2]];
    const struct rgbvec c111 = lut3d->lut[next[0]][next[1]][next[2]];
    const struct rgbvec c00 = lerp(&c000, &c100, d.r);
    const struct rgbvec c10 = lerp(&c010, &c110, d.r);
    const struct rgbvec c01 = lerp(&c001, &c101, d.r);
    const struct rgbvec c11 = lerp(&c011, &c111, d.r);
    const struct rgbvec c0 = lerp(&c00, &c10, d.g);
    const struct rgbvec c1 = lerp(&c01, &c11, d.g);
    const struct rgbvec c = lerp(&c0, &c1, d.b);
    return (c);
}


/**
 * Tetrahedral interpolation. Based on code found in Truelight Software Library paper.
 * @see http://www.filmlight.ltd.uk/pdf/whitepapers/FL-TL-TN-0057-SoftwareLib.pdf
 */
static inline struct rgbvec interp_tetrahedral(const LUT3DContext *lut3d,
                                               const struct rgbvec *s) {
    const int prev[] = {PREV(s->r), PREV(s->g), PREV(s->b)};
    const int next[] = {NEXT(s->r), NEXT(s->g), NEXT(s->b)};
    const struct rgbvec d = {s->r - prev[0], s->g - prev[1], s->b - prev[2]};
    const struct rgbvec c000 = lut3d->lut[prev[0]][prev[1]][prev[2]];
    const struct rgbvec c111 = lut3d->lut[next[0]][next[1]][next[2]];
    struct rgbvec c;
    if (d.r > d.g) {
        if (d.g > d.b) {
            const struct rgbvec c100 = lut3d->lut[next[0]][prev[1]][prev[2]];
            const struct rgbvec c110 = lut3d->lut[next[0]][next[1]][prev[2]];
            c.r = (1 - d.r) * c000.r + (d.r - d.g) * c100.r + (d.g - d.b) * c110.r + (d.b) * c111.r;
            c.g = (1 - d.r) * c000.g + (d.r - d.g) * c100.g + (d.g - d.b) * c110.g + (d.b) * c111.g;
            c.b = (1 - d.r) * c000.b + (d.r - d.g) * c100.b + (d.g - d.b) * c110.b + (d.b) * c111.b;
        } else if (d.r > d.b) {
            const struct rgbvec c100 = lut3d->lut[next[0]][prev[1]][prev[2]];
            const struct rgbvec c101 = lut3d->lut[next[0]][prev[1]][next[2]];
            c.r = (1 - d.r) * c000.r + (d.r - d.b) * c100.r + (d.b - d.g) * c101.r + (d.g) * c111.r;
            c.g = (1 - d.r) * c000.g + (d.r - d.b) * c100.g + (d.b - d.g) * c101.g + (d.g) * c111.g;
            c.b = (1 - d.r) * c000.b + (d.r - d.b) * c100.b + (d.b - d.g) * c101.b + (d.g) * c111.b;
        } else {
            const struct rgbvec c001 = lut3d->lut[prev[0]][prev[1]][next[2]];
            const struct rgbvec c101 = lut3d->lut[next[0]][prev[1]][next[2]];
            c.r = (1 - d.b) * c000.r + (d.b - d.r) * c001.r + (d.r - d.g) * c101.r + (d.g) * c111.r;
            c.g = (1 - d.b) * c000.g + (d.b - d.r) * c001.g + (d.r - d.g) * c101.g + (d.g) * c111.g;
            c.b = (1 - d.b) * c000.b + (d.b - d.r) * c001.b + (d.r - d.g) * c101.b + (d.g) * c111.b;
        }
    } else {
        if (d.b > d.g) {
            const struct rgbvec c001 = lut3d->lut[prev[0]][prev[1]][next[2]];
            const struct rgbvec c011 = lut3d->lut[prev[0]][next[1]][next[2]];
            c.r = (1 - d.b) * c000.r + (d.b - d.g) * c001.r + (d.g - d.r) * c011.r + (d.r) * c111.r;
            c.g = (1 - d.b) * c000.g + (d.b - d.g) * c001.g + (d.g - d.r) * c011.g + (d.r) * c111.g;
            c.b = (1 - d.b) * c000.b + (d.b - d.g) * c001.b + (d.g - d.r) * c011.b + (d.r) * c111.b;
        } else if (d.b > d.r) {
            const struct rgbvec c010 = lut3d->lut[prev[0]][next[1]][prev[2]];
            const struct rgbvec c011 = lut3d->lut[prev[0]][next[1]][next[2]];
            c.r = (1 - d.g) * c000.r + (d.g - d.b) * c010.r + (d.b - d.r) * c011.r + (d.r) * c111.r;
            c.g = (1 - d.g) * c000.g + (d.g - d.b) * c010.g + (d.b - d.r) * c011.g + (d.r) * c111.g;
            c.b = (1 - d.g) * c000.b + (d.g - d.b) * c010.b + (d.b - d.r) * c011.b + (d.r) * c111.b;
        } else {
            const struct rgbvec c010 = lut3d->lut[prev[0]][next[1]][prev[2]];
            const struct rgbvec c110 = lut3d->lut[next[0]][next[1]][prev[2]];
            c.r = (1 - d.g) * c000.r + (d.g - d.r) * c010.r + (d.r - d.b) * c110.r + (d.b) * c111.r;
            c.g = (1 - d.g) * c000.g + (d.g - d.r) * c010.g + (d.r - d.b) * c110.g + (d.b) * c111.g;
            c.b = (1 - d.g) * c000.b + (d.g - d.r) * c010.b + (d.r - d.b) * c110.b + (d.b) * c111.b;
        }
    }
    return (c);
}


/**
 * Locale-independent conversion of ASCII isspace.
 */
int _isspace(int c) {
    return (c == ' ' || c == '\f' || c == '\n' || c == '\r' || c == '\t' ||
            c == '\v');
}


/**
 * Clip a signed integer value into the 0-65535 range.
 * @param a value to clip
 * @return clipped value
 */
static uint16_t clip_uint16(int a) {
    if (a & (~0xFFFF))
        return ((~a) >> 31);
    else return (a);
}


/**
 * Clip a signed integer value into the 0-255 range.
 * @param a value to clip
 * @return clipped value
 */
static uint8_t clip_uint8(int a) {
    if (a & (~0xFF))
        return ((~a) >> 31);
    else return (a);
}


static unsigned clip_uintp2(int a, int p) {
    if (a & ~((1 << p) - 1))
        return (-a >> 31 & ((1 << p) - 1));
    else return (a);
}


#define DEFINE_INTERP_FUNC_PLANAR(name, nbits, depth)                             \
    static int interp_ ## nbits ## _ ## name ## _p ## depth( const LUT3DContext * lut3d, uint8_t * indata_g, uint8_t * indata_b, uint8_t * indata_r, uint8_t * indata_a, uint8_t * outdata_g, uint8_t * outdata_b, uint8_t * outdata_r, uint8_t * outdata_a, int width, int height, int linesize ) \
    {                                                       \
        int        x, y;                                             \
        int        direct        = (outdata_g == indata_g);                                    \
        uint8_t        *grow        = outdata_g  ;                   \
        uint8_t        *brow        = outdata_b  ;                   \
        uint8_t        *rrow        = outdata_r  ;                   \
        uint8_t        *arow        = outdata_a  ;                   \
        const uint8_t    *srcgrow    = indata_g  ;               \
        const uint8_t    *srcbrow    = indata_b  ;               \
        const uint8_t    *srcrrow    = indata_r  ;               \
        const uint8_t    *srcarow    = indata_a  ;               \
        const float    scale        = (1.f / ( (1 << (depth) ) - 1) ) * (lut3d->lutsize - 1);                \
        for ( y = 0; y < height; y++ ) {                            \
            uint ## nbits ## _t * dstg    = (uint ## nbits ## _t *)grow;                             \
            uint ## nbits ## _t * dstb    = (uint ## nbits ## _t *)brow;                             \
            uint ## nbits ## _t * dstr    = (uint ## nbits ## _t *)rrow;                             \
            uint ## nbits ## _t * dsta    = (uint ## nbits ## _t *)arow;                             \
            const    uint ## nbits ## _t *srcg = (const uint ## nbits ## _t *)srcgrow;                 \
            const    uint ## nbits ## _t *srcb = (const uint ## nbits ## _t *)srcbrow;                 \
            const    uint ## nbits ## _t *srcr = (const uint ## nbits ## _t *)srcrrow;                 \
            const    uint ## nbits ## _t *srca = (const uint ## nbits ## _t *)srcarow;                 \
            for ( x = 0; x < width; x++ ) {                                     \
                const struct rgbvec    scaled_rgb = { srcr[x] * scale,                        \
                                       srcg[x] * scale,                        \
                                       srcb[x] * scale };                     \
                struct rgbvec        vec = interp_ ## name( lut3d, &scaled_rgb );                     \
                dstr[x] = clip_uintp2( vec.r * (float) ( (1 << (depth) ) - 1), depth );                 \
                dstg[x] = clip_uintp2( vec.g * (float) ( (1 << (depth) ) - 1), depth );                 \
                dstb[x] = clip_uintp2( vec.b * (float) ( (1 << (depth) ) - 1), depth );                 \
                if ( !direct && linesize )                                  \
                    dsta[x] = srca[x];                                       \
            }                                                        \
            grow    += linesize;                                      \
            brow    += linesize;                                       \
            rrow    += linesize;                                       \
            arow    += linesize;                                        \
            srcgrow += linesize;                                     \
            srcbrow += linesize;                                     \
            srcrrow += linesize;                                      \
            srcarow += linesize;                                     \
        }                                                        \
        return 0;                                               \
    }

DEFINE_INTERP_FUNC_PLANAR(nearest, 8, 8)

DEFINE_INTERP_FUNC_PLANAR(trilinear, 8, 8)

DEFINE_INTERP_FUNC_PLANAR(tetrahedral, 8, 8)

DEFINE_INTERP_FUNC_PLANAR(nearest, 16, 9)

DEFINE_INTERP_FUNC_PLANAR(trilinear, 16, 9)

DEFINE_INTERP_FUNC_PLANAR(tetrahedral, 16, 9)

DEFINE_INTERP_FUNC_PLANAR(nearest, 16, 10)

DEFINE_INTERP_FUNC_PLANAR(trilinear, 16, 10)

DEFINE_INTERP_FUNC_PLANAR(tetrahedral, 16, 10)

DEFINE_INTERP_FUNC_PLANAR(nearest, 16, 12)

DEFINE_INTERP_FUNC_PLANAR(trilinear, 16, 12)

DEFINE_INTERP_FUNC_PLANAR(tetrahedral, 16, 12)

DEFINE_INTERP_FUNC_PLANAR(nearest, 16, 14)

DEFINE_INTERP_FUNC_PLANAR(trilinear, 16, 14)

DEFINE_INTERP_FUNC_PLANAR(tetrahedral, 16, 14)

DEFINE_INTERP_FUNC_PLANAR(nearest, 16, 16)

DEFINE_INTERP_FUNC_PLANAR(trilinear, 16, 16)

DEFINE_INTERP_FUNC_PLANAR(tetrahedral, 16, 16)

#define DEFINE_INTERP_FUNC(name, nbits)                                  \
    static int interp_ ## nbits ## _ ## name( LUT3DContext * lut3d, const uint8_t * indata, uint8_t * outdata, int width, int height, int linesize )     \
    {                                                    \
        int        x, y;                                                 \
        const int    direct    = outdata == indata;                                       \
        const int    step    = lut3d->step;                                     \
        const uint8_t    r    = lut3d->rgba_map[R];                                \
        const uint8_t    g    = lut3d->rgba_map[G];                                \
        const uint8_t    b    = lut3d->rgba_map[B];                                \
        const uint8_t    a    = lut3d->rgba_map[A];                                \
        uint8_t        *dstrow = outdata;                \
        const uint8_t    *srcrow = indata;               \
        const float    scale    = (1.f / ( (1 << nbits) - 1) ) * (lut3d->lutsize - 1);                  \
                                                    \
        for ( y = 0; y < height; y++ ) {                             \
            uint ## nbits ## _t * dst = (uint ## nbits ## _t *)dstrow;                         \
            const uint ## nbits ## _t *src = (const uint ## nbits ## _t *)srcrow;                    \
            for ( x = 0; x < width * step; x += step ) {                          \
                const struct rgbvec    scaled_rgb = { src[x + r] * scale,                     \
                                       src[x + g] * scale,                     \
                                       src[x + b] * scale };                      \
                struct rgbvec        vec = interp_ ## name( lut3d, &scaled_rgb );                      \
                dst[x + r]    = clip_uint ## nbits( vec.r * (float) ( (1 << nbits) - 1) );              \
                dst[x + g]    = clip_uint ## nbits( vec.g * (float) ( (1 << nbits) - 1) );              \
                dst[x + b]    = clip_uint ## nbits( vec.b * (float) ( (1 << nbits) - 1) );              \
                if ( !direct && step == 4 )                                  \
                    dst[x + a] = src[x + a];                                \
            }                                                \
            dstrow    += linesize;                                     \
            srcrow    += linesize;                                     \
        }                                                \
        return 0;                                            \
    }

DEFINE_INTERP_FUNC(nearest, 8)

DEFINE_INTERP_FUNC(trilinear, 8)

DEFINE_INTERP_FUNC(tetrahedral, 8)

DEFINE_INTERP_FUNC(nearest, 16)

DEFINE_INTERP_FUNC(trilinear, 16)

DEFINE_INTERP_FUNC(tetrahedral, 16)


static int skip_line(const char *p) {
    while (*p && _isspace(*p))
        p++;
    return (!*p || *p == '#');
}

#ifndef NEXT_LINE
#define NEXT_LINE(loop_cond) do {                  \
        if ( !fgets( line, sizeof(line), f ) ) {            \
            printf( "Unexpected EOF\n" );    fclose( f );  if ( lut3d ) free( lut3d );          \
            return NULL;                 \
        }                            \
} while ( loop_cond )
#endif

#ifndef MAX_LINE_SIZE
#define MAX_LINE_SIZE 512
#endif

/* Basically r g and b float values on each line, with a facultative 3DLUTSIZE
 * directive; seems to be generated by Davinci */
LUT3DContext *parse_dat(char *filename) {
    FILE *f = fopen(filename, "r");
    if (f == NULL) return NULL;
    LUT3DContext *lut3d = NULL;
    char line[MAX_LINE_SIZE];
    int i, j, k, size;

    int lutsize = size = 33;

    NEXT_LINE(skip_line(line));
    if (!strncmp(line, "3DLUTSIZE ", 10)) {
        size = strtol(line + 10, NULL, 0);
        if (size < 2 || size > MAX_LEVEL) {
            printf("Too large or invalid 3D LUT size\n");
            fclose(f);
            return (NULL);
        }
        lutsize = size;
        NEXT_LINE(skip_line(line));
    }
    if (size != 0 && lut3d == NULL) {
        lut3d = (LUT3DContext *) calloc(1, sizeof(LUT3DContext));
    }
    lut3d->lutsize = lutsize;
    for (k = 0; k < size; k++) {
        for (j = 0; j < size; j++) {
            for (i = 0; i < size; i++) {
                struct rgbvec *vec = &lut3d->lut[k][j][i];
                if (k != 0 || j != 0 || i != 0)
                    NEXT_LINE(skip_line(line));
                if (sscanf(line, "%f %f %f", &vec->r, &vec->g, &vec->b) != 3) {
                    fclose(f);
                    free(lut3d);
                    return (NULL);
                }
            }
        }
    }
    fclose(f);
    return (lut3d);
}


LUT3DContext *parse_cube(char *filename) {
    FILE *f = fopen(filename, "r");
    if (f == NULL) return NULL;
    char line[MAX_LINE_SIZE];
    float min[3] = {0.0, 0.0, 0.0};
    float max[3] = {1.0, 1.0, 1.0};
    int lutsize = 0;
    LUT3DContext *lut3d = NULL;
    while (fgets(line, sizeof(line), f)) {
        if (!strncmp(line, "LUT_3D_SIZE ", 12)) {
            int i, j, k;
            const int size = strtol(line + 12, NULL, 0);
            if (size < 2 || size > MAX_LEVEL) {
                printf("Too large or invalid 3D LUT size\n");
                fclose(f);
                return (NULL);
            }
            lutsize = size;
            if (size != 0 && lut3d == NULL) {
                lut3d = (LUT3DContext *) calloc(1, sizeof(LUT3DContext));
            }
            lut3d->lutsize = lutsize;
            for (k = 0; k < size; k++) {
                for (j = 0; j < size; j++) {
                    for (i = 0; i < size; i++) {
                        struct rgbvec *vec = &lut3d->lut[i][j][k];

                        do {
                            try_again:
                            NEXT_LINE(0);
                            if (!strncmp(line, "DOMAIN_", 7)) {
                                float *vals = NULL;
                                if (!strncmp(line + 7, "MIN ", 4))
                                    vals = min;
                                else if (!strncmp(line + 7, "MAX ", 4))
                                    vals = max;
                                if (!vals) {
                                    fclose(f);
                                    free(lut3d);
                                    return (NULL);
                                }

                                sscanf(line + 11, "%f %f %f", vals, vals + 1, vals + 2);
                                //printf("min: %f %f %f | max: %f %f %f\n",     min[0], min[1], min[2], max[0], max[1], max[2]);
                                goto try_again;
                            }
                        } while (skip_line(line));
                        if (sscanf(line, "%f %f %f", &vec->r, &vec->g, &vec->b) != 3) {
                            fclose(f);
                            free(lut3d);
                            return (NULL);
                        }
                        vec->r *= max[0] - min[0];
                        vec->g *= max[1] - min[1];
                        vec->b *= max[2] - min[2];
                    }
                }
            }
            break;
        }
    }
    fclose(f);
    return (lut3d);
}


/* Assume 17x17x17 LUT with a 16-bit depth   */
LUT3DContext *parse_3dl(char *filename) {
    FILE *f = fopen(filename, "r");
    if (f == NULL) return NULL;
    char line[MAX_LINE_SIZE];
    int i, j, k;
    const int size = 17;
    const float scale = 16 * 16 * 16;

    int lutsize = size;
    LUT3DContext *lut3d = (LUT3DContext *) calloc(1, sizeof(LUT3DContext));

    lut3d->lutsize = lutsize;
    NEXT_LINE(skip_line(line));
    for (k = 0; k < size; k++) {
        for (j = 0; j < size; j++) {
            for (i = 0; i < size; i++) {
                int r, g, b;
                struct rgbvec *vec = &lut3d->lut[k][j][i];

                NEXT_LINE(skip_line(line));
                if (sscanf(line, "%d %d %d", &r, &g, &b) != 3) {
                    fclose(f);
                    free(lut3d);
                    return (NULL);
                }
                vec->r = r / scale;
                vec->g = g / scale;
                vec->b = b / scale;
            }
        }
    }
    fclose(f);
    return (lut3d);
}


/* Pandora format */
LUT3DContext *parse_m3d(char *filename) {
    FILE *f = fopen(filename, "r");
    if (f == NULL) return NULL;
    float scale;
    int i, j, k, size, in = -1, out = -1;
    char line[MAX_LINE_SIZE];
    uint8_t rgb_map[3] = {0, 1, 2};

    while (fgets(line, sizeof(line), f)) {
        if (!strncmp(line, "in", 2))
            in = strtol(line + 2, NULL, 0);
        else if (!strncmp(line, "out", 3))
            out = strtol(line + 3, NULL, 0);
        else if (!strncmp(line, "values", 6)) {
            const char *p = line + 6;
#define SET_COLOR(id) do {              \
        while ( _isspace( *p ) )          \
            p++;                    \
        switch ( *p ) {                  \
        case 'r': rgb_map[id]    = 0; break;      \
        case 'g': rgb_map[id]    = 1; break;      \
        case 'b': rgb_map[id]    = 2; break;      \
        }                    \
        while ( *p && !_isspace( *p ) )          \
            p++;                    \
} \
    while ( 0 )
            SET_COLOR(0);
            SET_COLOR(1);
            SET_COLOR(2);
            break;
        }
    }

    if (in == -1 || out == -1) {
        printf("in and out must be defined\n");
        fclose(f);
        return (NULL);
    }
    if (in < 2 || out < 2 ||
        in > MAX_LEVEL * MAX_LEVEL * MAX_LEVEL ||
        out > MAX_LEVEL * MAX_LEVEL * MAX_LEVEL) {
        printf("invalid in (%d) or out (%d)\n", in, out);
        fclose(f);
        return (NULL);
    }
    for (size = 1; size * size * size < in; size++);
    {}
    int lutsize = size;
    scale = 1.f / (out - 1);
    LUT3DContext *lut3d = NULL;
    if (size != 0) {
        lut3d = (LUT3DContext *) calloc(1, sizeof(LUT3DContext));
    }
    lut3d->lutsize = lutsize;
    for (k = 0; k < size; k++) {
        for (j = 0; j < size; j++) {
            for (i = 0; i < size; i++) {
                struct rgbvec *vec = &lut3d->lut[k][j][i];

                float val[3];
                NEXT_LINE(0);
                if (sscanf(line, "%f %f %f", val, val + 1, val + 2) != 3) {
                    fclose(f);
                    free(lut3d);
                    return (NULL);
                }
                vec->r = val[rgb_map[0]] * scale;
                vec->g = val[rgb_map[1]] * scale;
                vec->b = val[rgb_map[2]] * scale;
            }
        }
    }
    fclose(f);
    return (lut3d);
}


LUT3DContext *lut3d_load(char *filename) {
    int ret = 0;
    const char *ext;
    if (!filename) {
        return (0);
    }
    LUT3DContext *lut3d = NULL;

    ext = strrchr(filename, '.');
    if (!ext) {
        printf("Unable to guess the format from the extension\n");
        goto end;
    }
    ext++;

    if (!strcasecmp(ext, "dat")) {
        lut3d = parse_dat(filename);
    } else if (!strcasecmp(ext, "3dl")) {
        lut3d = parse_3dl(filename);
    } else if (!strcasecmp(ext, "cube")) {
        lut3d = parse_cube(filename);
    } else if (!strcasecmp(ext, "m3d")) {
        lut3d = parse_m3d(filename);
    } else {
        printf("Unrecognized '.%s' file type\n", ext);
        ret = -1;
    }
    if (!ret && !lut3d->lutsize) {
        printf("3D LUT is empty\n");
    }
    end:
    return (lut3d);
}


typedef int (action_planar_func)(const LUT3DContext *lut3d, uint8_t *indata_g, uint8_t *indata_b, uint8_t *indata_r,
                                 uint8_t *indata_a, uint8_t *outdata_g, uint8_t *outdata_b, uint8_t *outdata_r,
                                 uint8_t *outdata_a, int width, int height, int linesize);

static int apply_planar_lut(char *filename, uint8_t *indata_g, uint8_t *indata_b, uint8_t *indata_r,
                            uint8_t *indata_a, uint8_t *outdata_g, uint8_t *outdata_b, uint8_t *outdata_r,
                            uint8_t *outdata_a, int width, int height, int linesize, int depth, int interpolation
) {
    action_planar_func *interp_func = 0;

    LUT3DContext *lut3d = lut3d_load(filename);
    if (lut3d == NULL)
        return (-1);
    lut3d->step = depth;
    int planar = 1;     \

#define SET_PLANAR_FUNC(name) do {                     \
        if ( planar ) {                              \
            switch ( depth ) {                      \
            case  8: interp_func    = interp_8_ ## name ## _p8;   break; \
            case  9: interp_func    = interp_16_ ## name ## _p9;  break; \
            case 10: interp_func    = interp_16_ ## name ## _p10; break; \
            case 12: interp_func    = interp_16_ ## name ## _p12; break; \
            case 14: interp_func    = interp_16_ ## name ## _p14; break; \
            case 16: interp_func    = interp_16_ ## name ## _p16; break; \
            }                            \
        }      \
} while ( 0 )

    switch (interpolation) {
        case INTERPOLATE_NEAREST:
            SET_PLANAR_FUNC(nearest);
            break;
        case INTERPOLATE_TRILINEAR:
            SET_PLANAR_FUNC(trilinear);
            break;
        case INTERPOLATE_TETRAHEDRAL:
            SET_PLANAR_FUNC(tetrahedral);
            break;
        default:
            assert(0);
    }
    interp_func(lut3d, indata_g, indata_b, indata_r,
                indata_a, outdata_g, outdata_b, outdata_r,
                outdata_a, width, height, linesize);
    return (0);
}


typedef int (action_func)(LUT3DContext *lut3d, const uint8_t *indata, uint8_t *outdata, int width, int height,
                          int linesize);


static int
apply_lut(char *filename, const uint8_t *indata, uint8_t *outdata, int width, int height, int linesize, int depth,
          int interpolation, int is16bit) {
    action_func *interp_func = 0;

    LUT3DContext *lut3d = lut3d_load(filename);
    
    if (lut3d == NULL)
        return (-1);
     lut3d->rgba_map[0] = 0;
    lut3d->rgba_map[1] = 1;
    lut3d->rgba_map[2] = 2;
    lut3d->rgba_map[3] = 3;
        
    lut3d->step = depth;

#define SET_FUNC(name) do {                      \
        if ( is16bit ) { interp_func = interp_16_ ## name;     \
        } else { interp_func = interp_8_ ## name; }          \
} while ( 0 )

    switch (interpolation) {
        case INTERPOLATE_NEAREST:
            SET_FUNC(nearest);
            break;
        case INTERPOLATE_TRILINEAR:
            SET_FUNC(trilinear);
            break;
        case INTERPOLATE_TETRAHEDRAL:
            SET_FUNC(tetrahedral);
            break;
        default:
            assert(0);
    }
    interp_func(lut3d, indata, outdata, width, height, linesize);
    free(lut3d);
    return (0);
}

 
char saveFile[1024];
 
unsigned char *loadImage(const char *filename, int *Width, int *Height, int *Channels) {
    return (stbi_load(filename, Width, Height, Channels, 0));
}

 
void saveImage(const char *filename, int Width, int Height, int Channels, unsigned char *Output) {
    memcpy(saveFile + strlen(saveFile), filename, strlen(filename));
    *(saveFile + strlen(saveFile) + 1) = 0;
  
    if (!tje_encode_to_file(saveFile, Width, Height, Channels, true, Output)) {
        fprintf(stderr, "save JPEG fail.\n");
        return;
    }

#ifdef USE_SHELL_OPEN
    browse(saveFile);
#endif
}

 
void splitpath(const char *path, char *drv, char *dir, char *name, char *ext) {
    const char *end;
    const char *p;
    const char *s;
    if (path[0] && path[1] == ':') {
        if (drv) {
            *drv++ = *path++;
            *drv++ = *path++;
            *drv = '\0';
        }
    } else if (drv)
        *drv = '\0';
    for (end = path; *end && *end != ':';)
        end++;
    for (p = end; p > path && *--p != '\\' && *p != '/';)
        if (*p == '.') {
            end = p;
            break;
        }
    if (ext)
        for (s = end; (*ext = *s++);)
            ext++;
    for (p = end; p > path;)
        if (*--p == '\\' || *p == '/') {
            p++;
            break;
        }
    if (name) {
        for (s = p; s < end;)
            *name++ = *s++;
        *name = '\0';
    }
    if (dir) {
        for (s = path; s < p;)
            *dir++ = *s++;
        *dir = '\0';
    }
} 

void getCurrentFilePath(const char *filePath, char *saveFile) {
    char drive[_MAX_DRIVE];
    char dir[_MAX_DIR];
    char fname[_MAX_FNAME];
    char ext[_MAX_EXT];
    splitpath(filePath, drive, dir, fname, ext);
    size_t n = strlen(filePath);
    memcpy(saveFile, filePath, n);
    char *cur_saveFile = saveFile + (n - strlen(ext));
    cur_saveFile[0] = '_';
    cur_saveFile[1] = 0;
}


int main(int argc, char **argv) {
    printf("lut 3d demo\n ");
    printf("blog:http://cpuimage.cnblogs.com/ \n ");

    if (argc < 3) {
        printf("usage: %s 3dlut image \n ", argv[0]);
        printf("eg: %s 3DLUT d:\\image.jpg \n ", argv[0]);

        return (0);
    }
    char *lutfile = argv[1];
    char *szfile = argv[2];

    getCurrentFilePath(szfile, saveFile);

    int Width = 0;
    int Height = 0;
    int Channels = 0;
    unsigned char *inputImage = NULL;

    double startTime = now();
    inputImage = loadImage(szfile, &Width, &Height, &Channels);

    double nLoadTime = calcElapsed(startTime, now());
    printf("load time: %d ms.\n ", (int) (nLoadTime * 1000));
    if ((Channels != 0) && (Width != 0) && (Height != 0)) {
        unsigned char *outputImg = (unsigned char *) stbi__malloc(Width * Channels * Height * sizeof(unsigned char));
        if (inputImage) {
            memcpy(outputImg, inputImage, Width * Channels * Height);
        } else {
            printf("load: %s fail!\n ", szfile);
        }
        startTime = now();

        int is16bit = 0;
        //  INTERPOLATE_NEAREST
        //    INTERPOLATE_TRILINEAR
        //    INTERPOLATE_TETRAHEDRAL
        int interp_mode = INTERPOLATE_TETRAHEDRAL;
        apply_lut(lutfile, inputImage, outputImg, Width, Height, Width * Channels, Channels, interp_mode,
                  is16bit);
        double nProcessTime = calcElapsed(startTime, now());

        printf("process time: %d ms.\n ", (int) (nProcessTime * 1000));

        startTime = now();

        saveImage("_done.jpg", Width, Height, Channels, outputImg);
        double nSaveTime = calcElapsed(startTime, now());

        printf("save time: %d ms.\n ", (int) (nSaveTime * 1000));

        if (outputImg) {
            stbi_image_free(outputImg);
        }

        if (inputImage) {
            stbi_image_free(inputImage);
        }
    } else {
        printf("load: %s fail!\n", szfile);
    }

    getchar();
    printf("press any key to exit. \n");

    return (EXIT_SUCCESS);
}

项目地址:

https://github.com/cpuimage/Lut3D

命令行参数:

lut3d 3d预设文件  图片路径

例如: lut3d ../god.cube ../sample.jpg

用cmake即可进行编译示例代码,详情见CMakeLists.txt。

算法细节就不展开说了,

若有其他相关问题或者需求也可以邮件联系俺探讨。

邮箱地址是:  gaozhihan@vip.qq.com

原创声明,本文系作者授权云+社区发表,未经许可,不得转载。

如有侵权,请联系 yunjia_community@tencent.com 删除。

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