radiance_hdr.c

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/*
 * ***** BEGIN GPL LICENSE BLOCK *****
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright
 * All rights reserved.
 *
 * The Original Code is: all of this file.
 *
 * Contributor(s): none yet.
 *
 * ***** END GPL LICENSE BLOCK *****
 */

/* ----------------------------------------------------------------------
  Radiance High Dynamic Range image file IO
  For description and code for reading/writing of radiance hdr files 
    by Greg Ward, refer to:
  http://radsite.lbl.gov/radiance/refer/Notes/picture_format.html
----------------------------------------------------------------------
*/

#ifdef WIN32
#  include <io.h>
#endif

#include "MEM_guardedalloc.h"

#include "BLI_blenlib.h"

#include "imbuf.h"

#include "IMB_imbuf_types.h"
#include "IMB_imbuf.h"

#include "IMB_allocimbuf.h"
#include "IMB_filetype.h"

/* needed constants */
#define MINELEN 8
#define MAXELEN 0x7fff
#define MINRUN  4   /* minimum run length */
#define RED 0
#define GRN 1
#define BLU 2
#define EXP 3
#define COLXS 128
#define STR_MAX 540
typedef unsigned char RGBE[4];
typedef float fCOLOR[3];
/* copy source -> dest */
#define copy_rgbe(c1, c2) (c2[RED]=c1[RED], c2[GRN]=c1[GRN], c2[BLU]=c1[BLU], c2[EXP]=c1[EXP])
#define copy_fcol(f1, f2) (f2[RED]=f1[RED], f2[GRN]=f1[GRN], f2[BLU]=f1[BLU])

/* read routines */
static unsigned char* oldreadcolrs(RGBE *scan, unsigned char *mem, int xmax)
{
    int i, rshift = 0, len = xmax;
    while (len > 0) {
        scan[0][RED] = *mem++;
        scan[0][GRN] = *mem++;
        scan[0][BLU] = *mem++;
        scan[0][EXP] = *mem++;
        if (scan[0][RED] == 1 && scan[0][GRN] == 1 && scan[0][BLU] == 1) {
            for (i=scan[0][EXP]<<rshift;i>0;i--) {
                copy_rgbe(scan[-1], scan[0]);
                scan++;
                len--;
            }
            rshift += 8;
        }
        else {
            scan++;
            len--;
            rshift = 0;
        }
    }
    return mem;
}

static unsigned char* freadcolrs(RGBE *scan, unsigned char* mem, int xmax)
{
    int i, j, code, val;

    if ((xmax < MINELEN) | (xmax > MAXELEN)) return oldreadcolrs(scan, mem, xmax);

    i = *mem++;
    if (i != 2) return oldreadcolrs(scan, mem-1, xmax);

    scan[0][GRN] = *mem++;
    scan[0][BLU] = *mem++;

    i = *mem++;
    if (((scan[0][BLU] << 8) | i) != xmax) return NULL;

    for (i=0;i<4;i++)
        for (j=0;j<xmax;) {
            code = *mem++;
            if (code > 128) {
                code &= 127;
                val = *mem++;
                while (code--)
                    scan[j++][i] = (unsigned char)val;
            }
            else
                while (code--)
                    scan[j++][i] = *mem++;
        }
    return mem;
}

/* helper functions */

/* rgbe -> float color */
static void RGBE2FLOAT(RGBE rgbe, fCOLOR fcol)
{
    if (rgbe[EXP]==0) {
        fcol[RED] = fcol[GRN] = fcol[BLU] = 0;
    }
    else {
        float f = ldexp(1.0, rgbe[EXP]-(COLXS+8));
        fcol[RED] = f*(rgbe[RED] + 0.5f);
        fcol[GRN] = f*(rgbe[GRN] + 0.5f);
        fcol[BLU] = f*(rgbe[BLU] + 0.5f);
    }
}

/* float color -> rgbe */
static void FLOAT2RGBE(fCOLOR fcol, RGBE rgbe)
{
    int e;
    float d = (fcol[RED]>fcol[GRN]) ? fcol[RED] : fcol[GRN];
    if (fcol[BLU]>d) d = fcol[BLU];
    if (d <= 1e-32f)
        rgbe[RED] = rgbe[GRN] = rgbe[BLU] = rgbe[EXP] = 0;
    else {
        d = frexp(d, &e) * 256.f / d;
        rgbe[RED] = (unsigned char)(fcol[RED] * d);
        rgbe[GRN] = (unsigned char)(fcol[GRN] * d);
        rgbe[BLU] = (unsigned char)(fcol[BLU] * d);
        rgbe[EXP] = (unsigned char)(e + COLXS);
    }
}

/* ImBuf read */

int imb_is_a_hdr(unsigned char *buf)
{
    // For recognition, Blender only loads first 32 bytes, so use #?RADIANCE id instead
    // update: actually, the 'RADIANCE' part is just an optional program name, the magic word is really only the '#?' part
    //if (strstr((char*)buf, "#?RADIANCE")) return 1;
    if (strstr((char*)buf, "#?")) return 1;
    // if (strstr((char*)buf, "32-bit_rle_rgbe")) return 1;
    return 0;
}

struct ImBuf *imb_loadhdr(unsigned char *mem, size_t size, int flags)
{
    struct ImBuf* ibuf;
    RGBE* sline;
    fCOLOR fcol;
    float* rect_float;
    int found=0;
    int width=0, height=0;
    int x, y;
    unsigned char* ptr;
    char oriY[80], oriX[80];

    if (imb_is_a_hdr((void*)mem))
    {
        /* find empty line, next line is resolution info */
        for (x=1;x<size;x++) {
            if ((mem[x-1]=='\n') && (mem[x]=='\n')) {
                found = 1;
                break;
            }
        }
        if (found && (x<(size + 2))) {
            if (sscanf((char *)&mem[x+1], "%79s %d %79s %d", (char*)&oriY, &height, 
                (char*)&oriX, &width) != 4) return NULL;

            /* find end of this line, data right behind it */
            ptr = (unsigned char *)strchr((char*)&mem[x+1], '\n');
            ptr++;

            if (flags & IB_test) ibuf = IMB_allocImBuf(width, height, 32, 0);
            else ibuf = IMB_allocImBuf(width, height, 32, (flags & IB_rect)|IB_rectfloat);

            if (ibuf==NULL) return NULL;
            ibuf->ftype = RADHDR;
            ibuf->profile = IB_PROFILE_LINEAR_RGB;

            if (flags & IB_test) return ibuf;

            /* read in and decode the actual data */
            sline = (RGBE*)MEM_mallocN(sizeof(RGBE)*width, "radhdr_read_tmpscan");
            rect_float = (float *)ibuf->rect_float;
            
            for (y=0;y<height;y++) {
                ptr = freadcolrs(sline, ptr, width);
                if (ptr==NULL) {
                    printf("HDR decode error\n");
                    MEM_freeN(sline);
                    return ibuf;
                }
                for (x=0;x<width;x++) {
                    /* convert to ldr */
                    RGBE2FLOAT(sline[x], fcol);
                    *rect_float++ = fcol[RED];
                    *rect_float++ = fcol[GRN];
                    *rect_float++ = fcol[BLU];
                    *rect_float++ = 1.0f;
                }
            }
            MEM_freeN(sline);
            if (oriY[0]=='-') IMB_flipy(ibuf);
            
            if (flags & IB_rect) {
                IMB_rect_from_float(ibuf);
            }
            
            return ibuf;
        }
        //else printf("Data not found!\n");
    }
    //else printf("Not a valid radiance HDR file!\n");

    return NULL;
}

/* ImBuf write */
static int fwritecolrs(FILE* file, int width, int channels, unsigned char* ibufscan, float* fpscan)
{
    int x, i, j, beg, c2, cnt=0;
    fCOLOR fcol;
    RGBE rgbe, *rgbe_scan;

    if ((ibufscan==NULL) && (fpscan==NULL)) return 0;

    rgbe_scan = (RGBE*)MEM_mallocN(sizeof(RGBE)*width, "radhdr_write_tmpscan");

    /* convert scanline */
        j= 0;
    for (i=0;i<width;i++) {
        if (fpscan) {
            fcol[RED] = fpscan[j];
            fcol[GRN] = (channels >= 2)? fpscan[j+1]: fpscan[j];
            fcol[BLU] = (channels >= 3)? fpscan[j+2]: fpscan[j];
        } else {
            fcol[RED] = (float)ibufscan[j] / 255.f;
            fcol[GRN] = (float)((channels >= 2)? ibufscan[j+1]: ibufscan[j]) / 255.f;
            fcol[BLU] = (float)((channels >= 3)? ibufscan[j+2]: ibufscan[j]) / 255.f;
        }
        FLOAT2RGBE(fcol, rgbe);
        copy_rgbe(rgbe, rgbe_scan[i]);
        j+=channels;
    }

    if ((width < MINELEN) | (width > MAXELEN)) {    /* OOBs, write out flat */
        x=fwrite((char *)rgbe_scan, sizeof(RGBE), width, file) - width;
        MEM_freeN(rgbe_scan);
        return x;
    }
    /* put magic header */
    putc(2, file);
    putc(2, file);
    putc((unsigned char)(width >> 8), file);
    putc((unsigned char)(width & 255), file);
    /* put components separately */
    for (i=0;i<4;i++) {
        for (j=0;j<width;j+=cnt) {  /* find next run */
            for (beg=j;beg<width;beg+=cnt) {
                for (cnt=1;(cnt<127) && ((beg+cnt)<width) && (rgbe_scan[beg+cnt][i] == rgbe_scan[beg][i]); cnt++);
                if (cnt>=MINRUN) break;   /* long enough */
            }
            if (((beg-j)>1) && ((beg-j) < MINRUN)) {
                c2 = j+1;
                while (rgbe_scan[c2++][i] == rgbe_scan[j][i])
                    if (c2 == beg) {        /* short run */
                        putc((unsigned char)(128+beg-j), file);
                        putc((unsigned char)(rgbe_scan[j][i]), file);
                        j = beg;
                        break;
                    }
            }
            while (j < beg) {     /* write out non-run */
                if ((c2 = beg-j) > 128) c2 = 128;
                putc((unsigned char)(c2), file);
                while (c2--) putc(rgbe_scan[j++][i], file);
            }
            if (cnt >= MINRUN) {      /* write out run */
                putc((unsigned char)(128+cnt), file);
                putc(rgbe_scan[beg][i], file);
            }
            else cnt = 0;
        }
    }
    MEM_freeN(rgbe_scan);
    return(ferror(file) ? -1 : 0);
}

static void writeHeader(FILE *file, int width, int height)
{
    fprintf(file, "#?RADIANCE");
    fputc(10, file);
    fprintf(file, "# %s", "Created with Blender");
    fputc(10, file);
    fprintf(file, "EXPOSURE=%25.13f", 1.0);
    fputc(10, file);
    fprintf(file, "FORMAT=32-bit_rle_rgbe");
    fputc(10, file);
    fputc(10, file);
    fprintf(file, "-Y %d +X %d", height, width);
    fputc(10, file);
}

int imb_savehdr(struct ImBuf *ibuf, const char *name, int flags)
{
    FILE* file = fopen(name, "wb");
    float *fp= NULL;
    int y, width=ibuf->x, height=ibuf->y;
    unsigned char *cp= NULL;
    
    (void)flags; /* unused */
    
    if (file==NULL) return 0;

    writeHeader(file, width, height);

    if(ibuf->rect)
        cp= (unsigned char *)ibuf->rect + ibuf->channels*(height-1)*width;
    if(ibuf->rect_float)
        fp= ibuf->rect_float + ibuf->channels*(height-1)*width;
    
    for (y=height-1;y>=0;y--) {
        if (fwritecolrs(file, width, ibuf->channels, cp, fp) < 0) {
            fclose(file);
            printf("HDR write error\n");
            return 0;
        }
        if(cp) cp-= ibuf->channels*width;
        if(fp) fp-= ibuf->channels*width;
    }

    fclose(file);
    return 1;
}