I process my photos with a combination of dcraw, imagemagick and g’mic but only just discovered this site!
I see a thread on Pentax pixel-shift, but does anyone have any insight into Olympus Hi-Res mode? I don’t have the hardware but RAW and JPG files are available at Imaging Resorce. I looked at the 80Mp RAW and corresponding 50Mp JPG files from the E-M1 MkII.
Dcraw extracts an 80Mp image from the RAW, but it looks soft and I am unable to process it to anywhere near the sharpness of the 50Mb out-of-camera JPEG. I tried RT on the same file - it loads and displays an image but when I try to save it appears to work, but nothing is written to the disk!
It is also a mystery to me how (a) Olympus creates an 80Mp from 8 x 20Mp images and (b) why and how they downscale to 50Mb for the JPEG output.
In dcraw the -s switch has no effect - it appears there is only one 80Mp image in there. Are they doing some kind of tricky demosaic with multiple images?
Olympus’ HiRes raws are not multiframe files, they are single frame coming from a mysterious incamera mix of 8 shots. Half of these shots have been captured at a shift of 0.7X diagonal with a lot of overlaping (about equal to 2X stronger than usual aa filter).
From these 8 shots a full color (3 colors per pixel) 40Mp diagonal grid are then mixed and then this gets transformed to a Bayer 80Mp grid (1 color per pixel) … there is a slight data loss as R and B data loose 1/2 of their sampling density i.e we have 20Mp R B instead of the 40Mp captured.
Because of the overlaping we take a soft picture (but this also gives perfect antialiasing ) … so for the Hires raws we need to use 1.5-2.0X stronger sharpening … compared with a normal raw coming from a sensor with no aa filter we need to increase radius by 1.4 and strength about so, to take about equal per pixel aquity (and a lot better details).
Thanks for the quick reply! That is very interesting information.
You are right - I was much too cautious in sharpening the output. Now it looks very good.
Perhaps the E-M1 MkII can position the sensor more accurately than its predecessors and we will see a bit more detail from the images. It looks like quite a jump compared to the standard 20Mp capture. More than I recall from the E-M5 MkII samples.