Dear Developers,
while examining raw files from Olympus OM-D E-M5MarkII i've found that
coding is fairly simple, no compression - just packing of 2x12bpp into 3
bytes. Based on Dave Coffin's dcraw here is my version of load_raw just for
this case:
void CLASS olympus_load_hires()
{
uchar buf[16];
unsigned val;
int row, col, i=15;
for (row=0; row < height; row++) {
for (col=0; col < raw_width; col+=2) {
if(i==15) {
fread(buf, 16, 1, ifp);
i=0;
}
val = *(unsigned *)(&buf[i]);
BAYER(row,col) = val & 0x00000fff;
BAYER(row, col+1) = (val>>12) & 0x00000fff;
i+=3;
}
}
}
The file is read by 16 bytes chunks, 15 of them is decoded into 5 pixels,
buf[15] is always 0 (unused).
Total length of strip is width x height x 1.6, ie 9280 x 6932 x 1.6 =
102926336, as indicated by tag #0x0117; this may be used as indication of
HiRes shot. It's possible that tag #0x0604 (ImageQuality3) also depends on
mode (0=HiRes, 1=Normal), but it's only guess.
Please feel free to use this idea in next release of DarkTable!
Yours,
Krzysztof Spera
PS. Same info sent to Dave.
K
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