/*
Simple reference decompresser for Canon digital cameras.
Outputs raw 16-bit CCD data, no header, native byte order.
$Revision: 1.12 $
$Date: 2004/08/06 00:08:01 $
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
typedef unsigned char uchar;
/* Global Variables */
FILE *ifp;
short order;
int height, width, table, lowbits;
char name[64];
struct decode {
struct decode *branch[2];
int leaf;
} first_decode[32], second_decode[512];
/*
Get a 2-byte integer, making no assumptions about CPU byte order.
Nor should we assume that the compiler evaluates left-to-right.
*/
short fget2 (FILE *f)
{
register uchar a, b;
a = fgetc(f);
b = fgetc(f);
if (order == 0x4d4d) /* "MM" means big-endian */
return (a << 8) + b;
else /* "II" means little-endian */
return a + (b << 8);
}
/*
Same for a 4-byte integer.
*/
int fget4 (FILE *f)
{
register uchar a, b, c, d;
a = fgetc(f);
b = fgetc(f);
c = fgetc(f);
d = fgetc(f);
if (order == 0x4d4d)
return (a << 24) + (b << 16) + (c << 8) + d;
else
return a + (b << 8) + (c << 16) + (d << 24);
}
/*
Parse the CIFF structure
*/
void parse (int offset, int length)
{
int tboff, nrecs, i, type, len, roff, aoff, save;
fseek (ifp, offset+length-4, SEEK_SET);
tboff = fget4(ifp) + offset;
fseek (ifp, tboff, SEEK_SET);
nrecs = fget2(ifp);
for (i = 0; i < nrecs; i++) {
type = fget2(ifp);
len = fget4(ifp);
roff = fget4(ifp);
aoff = offset + roff;
save = ftell(ifp);
if (type == 0x080a) { /* Get the camera name */
fseek (ifp, aoff, SEEK_SET);
while (fgetc(ifp));
fread (name, 64, 1, ifp);
}
if (type == 0x1031) { /* Get the width and height */
fseek (ifp, aoff+2, SEEK_SET);
width = fget2(ifp);
height = fget2(ifp);
}
if (type == 0x1835) { /* Get the decoder table */
fseek (ifp, aoff, SEEK_SET);
table = fget4(ifp);
}
if (type >> 8 == 0x28 || type >> 8 == 0x30) /* Get sub-tables */
parse (aoff, len);
fseek (ifp, save, SEEK_SET);
}
}
/*
Return 0 if the image starts with compressed data,
1 if it starts with uncompressed low-order bits.
In Canon compressed data, 0xff is always followed by 0x00.
*/
int canon_has_lowbits()
{
uchar test[0x4000];
int ret=1, i;
fseek (ifp, 0, SEEK_SET);
fread (test, 1, sizeof test, ifp);
for (i=540; i < sizeof test - 1; i++)
if (test[i] == 0xff) {
if (test[i+1]) return 1;
ret=0;
}
return ret;
}
/*
Open a CRW file, identify which camera created it, and set
global variables accordingly. Returns nonzero if an error occurs.
*/
int open_and_id(char *fname)
{
char head[8];
int hlen;
ifp = fopen(fname,"rb");
if (!ifp) {
perror(fname);
return 1;
}
order = fget2(ifp);
hlen = fget4(ifp);
fread (head, 1, 8, ifp);
if (memcmp(head,"HEAPCCDR",8) || (order != 0x4949 && order != 0x4d4d)) {
fprintf(stderr,"%s is not a Canon CRW file.\n",fname);
return 1;
}
name[0] = 0;
table = -1;
fseek (ifp, 0, SEEK_END);
parse (hlen, ftell(ifp) - hlen);
lowbits = canon_has_lowbits();
fprintf(stderr,"name = %s, width = %d, height = %d, table = %d, bpp = %d\n",
name, width, height, table, 10+lowbits*2);
if (table < 0) {
fprintf(stderr,"Cannot decompress %s!!\n",fname);
return 1;
}
return 0;
}
/*
A rough description of Canon's compression algorithm:
+ Each pixel outputs a 10-bit sample, from 0 to 1023.
+ Split the data into blocks of 64 samples each.
+ Subtract from each sample the value of the sample two positions
to the left, which has the same color filter. From the two
leftmost samples in each row, subtract 512.
+ For each nonzero sample, make a token consisting of two four-bit
numbers. The low nibble is the number of bits required to
represent the sample, and the high nibble is the number of
zero samples preceding this sample.
+ Output this token as a variable-length bitstring using
one of three tablesets. Follow it with a fixed-length
bitstring containing the sample.
The "first_decode" table is used for the first sample in each
block, and the "second_decode" table is used for the others.
*/
/*
Construct a decode tree according the specification in *source.
The first 16 bytes specify how many codes should be 1-bit, 2-bit
3-bit, etc. Bytes after that are the leaf values.
For example, if the source is
{ 0,1,4,2,3,1,2,0,0,0,0,0,0,0,0,0,
0x04,0x03,0x05,0x06,0x02,0x07,0x01,0x08,0x09,0x00,0x0a,0x0b,0xff },
then the code is
00 0x04
010 0x03
011 0x05
100 0x06
101 0x02
1100 0x07
1101 0x01
11100 0x08
11101 0x09
11110 0x00
111110 0x0a
1111110 0x0b
1111111 0xff
*/
void make_decoder(struct decode *dest, const uchar *source, int level)
{
static struct decode *free; /* Next unused node */
static int leaf; /* no. of leaves already added */
int i, next;
if (level==0) {
free = dest;
leaf = 0;
}
free++;
/*
At what level should the next leaf appear?
*/
for (i=next=0; i <= leaf && next < 16; )
i += source[next++];
if (i > leaf)
if (level < next) { /* Are we there yet? */
dest->branch[0] = free;
make_decoder(free,source,level+1);
dest->branch[1] = free;
make_decoder(free,source,level+1);
} else
dest->leaf = source[16 + leaf++];
}
void init_tables(unsigned table)
{
static const uchar first_tree[3][29] = {
{ 0,1,4,2,3,1,2,0,0,0,0,0,0,0,0,0,
0x04,0x03,0x05,0x06,0x02,0x07,0x01,0x08,0x09,0x00,0x0a,0x0b,0xff },
{ 0,2,2,3,1,1,1,1,2,0,0,0,0,0,0,0,
0x03,0x02,0x04,0x01,0x05,0x00,0x06,0x07,0x09,0x08,0x0a,0x0b,0xff },
{ 0,0,6,3,1,1,2,0,0,0,0,0,0,0,0,0,
0x06,0x05,0x07,0x04,0x08,0x03,0x09,0x02,0x00,0x0a,0x01,0x0b,0xff },
};
static const uchar second_tree[3][180] = {
{ 0,2,2,2,1,4,2,1,2,5,1,1,0,0,0,139,
0x03,0x04,0x02,0x05,0x01,0x06,0x07,0x08,
0x12,0x13,0x11,0x14,0x09,0x15,0x22,0x00,0x21,0x16,0x0a,0xf0,
0x23,0x17,0x24,0x31,0x32,0x18,0x19,0x33,0x25,0x41,0x34,0x42,
0x35,0x51,0x36,0x37,0x38,0x29,0x79,0x26,0x1a,0x39,0x56,0x57,
0x28,0x27,0x52,0x55,0x58,0x43,0x76,0x59,0x77,0x54,0x61,0xf9,
0x71,0x78,0x75,0x96,0x97,0x49,0xb7,0x53,0xd7,0x74,0xb6,0x98,
0x47,0x48,0x95,0x69,0x99,0x91,0xfa,0xb8,0x68,0xb5,0xb9,0xd6,
0xf7,0xd8,0x67,0x46,0x45,0x94,0x89,0xf8,0x81,0xd5,0xf6,0xb4,
0x88,0xb1,0x2a,0x44,0x72,0xd9,0x87,0x66,0xd4,0xf5,0x3a,0xa7,
0x73,0xa9,0xa8,0x86,0x62,0xc7,0x65,0xc8,0xc9,0xa1,0xf4,0xd1,
0xe9,0x5a,0x92,0x85,0xa6,0xe7,0x93,0xe8,0xc1,0xc6,0x7a,0x64,
0xe1,0x4a,0x6a,0xe6,0xb3,0xf1,0xd3,0xa5,0x8a,0xb2,0x9a,0xba,
0x84,0xa4,0x63,0xe5,0xc5,0xf3,0xd2,0xc4,0x82,0xaa,0xda,0xe4,
0xf2,0xca,0x83,0xa3,0xa2,0xc3,0xea,0xc2,0xe2,0xe3,0xff,0xff },
{ 0,2,2,1,4,1,4,1,3,3,1,0,0,0,0,140,
0x02,0x03,0x01,0x04,0x05,0x12,0x11,0x06,
0x13,0x07,0x08,0x14,0x22,0x09,0x21,0x00,0x23,0x15,0x31,0x32,
0x0a,0x16,0xf0,0x24,0x33,0x41,0x42,0x19,0x17,0x25,0x18,0x51,
0x34,0x43,0x52,0x29,0x35,0x61,0x39,0x71,0x62,0x36,0x53,0x26,
0x38,0x1a,0x37,0x81,0x27,0x91,0x79,0x55,0x45,0x28,0x72,0x59,
0xa1,0xb1,0x44,0x69,0x54,0x58,0xd1,0xfa,0x57,0xe1,0xf1,0xb9,
0x49,0x47,0x63,0x6a,0xf9,0x56,0x46,0xa8,0x2a,0x4a,0x78,0x99,
0x3a,0x75,0x74,0x86,0x65,0xc1,0x76,0xb6,0x96,0xd6,0x89,0x85,
0xc9,0xf5,0x95,0xb4,0xc7,0xf7,0x8a,0x97,0xb8,0x73,0xb7,0xd8,
0xd9,0x87,0xa7,0x7a,0x48,0x82,0x84,0xea,0xf4,0xa6,0xc5,0x5a,
0x94,0xa4,0xc6,0x92,0xc3,0x68,0xb5,0xc8,0xe4,0xe5,0xe6,0xe9,
0xa2,0xa3,0xe3,0xc2,0x66,0x67,0x93,0xaa,0xd4,0xd5,0xe7,0xf8,
0x88,0x9a,0xd7,0x77,0xc4,0x64,0xe2,0x98,0xa5,0xca,0xda,0xe8,
0xf3,0xf6,0xa9,0xb2,0xb3,0xf2,0xd2,0x83,0xba,0xd3,0xff,0xff },
{ 0,0,6,2,1,3,3,2,5,1,2,2,8,10,0,117,
0x04,0x05,0x03,0x06,0x02,0x07,0x01,0x08,
0x09,0x12,0x13,0x14,0x11,0x15,0x0a,0x16,0x17,0xf0,0x00,0x22,
0x21,0x18,0x23,0x19,0x24,0x32,0x31,0x25,0x33,0x38,0x37,0x34,
0x35,0x36,0x39,0x79,0x57,0x58,0x59,0x28,0x56,0x78,0x27,0x41,
0x29,0x77,0x26,0x42,0x76,0x99,0x1a,0x55,0x98,0x97,0xf9,0x48,
0x54,0x96,0x89,0x47,0xb7,0x49,0xfa,0x75,0x68,0xb6,0x67,0x69,
0xb9,0xb8,0xd8,0x52,0xd7,0x88,0xb5,0x74,0x51,0x46,0xd9,0xf8,
0x3a,0xd6,0x87,0x45,0x7a,0x95,0xd5,0xf6,0x86,0xb4,0xa9,0x94,
0x53,0x2a,0xa8,0x43,0xf5,0xf7,0xd4,0x66,0xa7,0x5a,0x44,0x8a,
0xc9,0xe8,0xc8,0xe7,0x9a,0x6a,0x73,0x4a,0x61,0xc7,0xf4,0xc6,
0x65,0xe9,0x72,0xe6,0x71,0x91,0x93,0xa6,0xda,0x92,0x85,0x62,
0xf3,0xc5,0xb2,0xa4,0x84,0xba,0x64,0xa5,0xb3,0xd2,0x81,0xe5,
0xd3,0xaa,0xc4,0xca,0xf2,0xb1,0xe4,0xd1,0x83,0x63,0xea,0xc3,
0xe2,0x82,0xf1,0xa3,0xc2,0xa1,0xc1,0xe3,0xa2,0xe1,0xff,0xff }
};
if (table > 2) table = 2;
memset( first_decode, 0, sizeof first_decode);
memset(second_decode, 0, sizeof second_decode);
make_decoder( first_decode, first_tree[table], 0);
make_decoder(second_decode, second_tree[table], 0);
}
#if 0
writebits (int val, int nbits)
{
val <<= 32 - nbits;
while (nbits--) {
putchar(val & 0x80000000 ? '1':'0');
val <<= 1;
}
}
#endif
/*
getbits(-1) initializes the buffer
getbits(n) where 0 <= n <= 25 returns an n-bit integer
*/
unsigned long getbits(int nbits)
{
static unsigned long bitbuf=0, ret=0;
static int vbits=0;
unsigned char c;
if (nbits == 0) return 0;
if (nbits == -1)
ret = bitbuf = vbits = 0;
else {
ret = bitbuf << (32 - vbits) >> (32 - nbits);
vbits -= nbits;
}
while (vbits < 25) {
c=fgetc(ifp);
bitbuf = (bitbuf << 8) + c;
if (c == 0xff) fgetc(ifp); /* always extra 00 after ff */
vbits += 8;
}
return ret;
}
int main(int argc, char **argv)
{
struct decode *decode, *dindex;
int i, j, leaf, len, diff, diffbuf[64], r, save;
int carry=0, column=0, base[2];
unsigned short outbuf[64];
uchar c;
if (argc < 2) {
fprintf(stderr,"Usage: %s file.crw\n",argv[0]);
exit(1);
}
if (open_and_id(argv[1]))
exit(1);
init_tables(table);
fseek (ifp, 540 + lowbits*height*width/4, SEEK_SET);
getbits(-1); /* Prime the bit buffer */
while (column < width * height) {
memset(diffbuf,0,sizeof diffbuf);
decode = first_decode;
for (i=0; i < 64; i++ ) {
for (dindex=decode; dindex->branch[0]; )
dindex = dindex->branch[getbits(1)];
leaf = dindex->leaf;
decode = second_decode;
if (leaf == 0 && i) break;
if (leaf == 0xff) continue;
i += leaf >> 4;
len = leaf & 15;
if (len == 0) continue;
diff = getbits(len);
if ((diff & (1 << (len-1))) == 0)
diff -= (1 << len) - 1;
if (i < 64) diffbuf[i] = diff;
}
diffbuf[0] += carry;
carry = diffbuf[0];
for (i=0; i < 64; i++ ) {
if (column++ % width == 0)
base[0] = base[1] = 512;
outbuf[i] = ( base[i & 1] += diffbuf[i] );
}
if (lowbits) {
save = ftell(ifp);
fseek (ifp, (column-64)/4 + 26, SEEK_SET);
for (i=j=0; j < 64/4; j++ ) {
c = fgetc(ifp);
for (r = 0; r < 8; r += 2)
outbuf[i++] = (outbuf[i] << 2) + ((c >> r) & 3);
}
fseek (ifp, save, SEEK_SET);
}
fwrite(outbuf,2,64,stdout);
}
return 0;
}
