UniWB for GH2?

[mcmorrison]

Hello,

I am interested in using a UniWB approach with my GH2, but I find that the GH2 will not allow a custom WB to be set with an overexposed frame, and that dcraw does not read GH2 files ( http://www.frostyplace.com/dcraw ).

Has anyone had success developing a uniWB approach for the GH2? If so, would you be willing to share how you did it, or perhaps the settings/file you generated?

Thanks!

Michael Morrison

[fdisilvestro]

According to Dave Coffin's page, the latest version of DCRaw supports the GH2. On the other hand it seems that the available compiled recent versions are only for Windows and I suppose you are on Mac, (because of the page you linked)

You might also try UFRaw, which is based on dcraw, (it supposedly has a version for Mac and supports the GH2, at least according to the documentation)

If you can't find a way to get a recent version of the program, maybe you could try with somebody with a windows or linux platform just to generate the test file out of dcraw without white balance.

[Guillermo Luijk]

David Coffin's page is probably a more reliable place than frostyplace.com to look for DCRAW's supported cameras  

Panasonic DMC-FZ8
Panasonic DMC-FZ18
Panasonic DMC-FZ28
Panasonic DMC-FZ30
Panasonic DMC-FZ35/FZ38
Panasonic DMC-FZ40
Panasonic DMC-FZ50
Panasonic DMC-FZ100
Panasonic DMC-FX150
Panasonic DMC-G1
Panasonic DMC-G2
Panasonic DMC-G3
Panasonic DMC-GF1
Panasonic DMC-GF2
Panasonic DMC-GF3
Panasonic DMC-GH1
Panasonic DMC-GH2
Panasonic DMC-L1
Panasonic DMC-L10
Panasonic DMC-LC1
Panasonic DMC-LX1
Panasonic DMC-LX2
Panasonic DMC-LX3
Panasonic DMC-LX5

[mcmorrison]

Hello,

Thanks for David Coffin's page! I now have dcraw running on my iMac, and have decoded a GH2 image. On to UniWB!

Best,

Michael

[mcmorrison]

Hello Guillermo,

Thank you so much for your great work and posts on all topics! I only wish you used the Mac. . . I am embarrassed to ask how you would find the "gray" pixel in the test shot using just PS, rather than ShowImage (PC only)?

Thanks in advance,

Michael

Got it: Duplicate, invert, difference.  Sorry. . .

[mcmorrison]

Hello,

Well, I have followed the procedure a few times, but keep getting large multipliers and non-neutral test shots. Upon inspection, I find that the color in the test shot looks diagonally transposed in terms of color. I have placed some registration dots in the corners to be sure of the orientation of the tiff produced by dcraw, and confirmed that there is no reflection in the image orientation. Following are screen shots of Guillermo's test chart and of the test image shot of it.

Thoughts?

Thanks,

Michael Morrison

EDIT: It looks like dcraw is inverting the R and B channels: is this possible?

[mcmorrison]

Hello,

Would someone with a later version of dcraw, (the Mac version is 8.99) be willing to decode my test file with Guillermo's command ( dcraw -v -r 1 1 1 1 -T ) and send it back to me? The test file can be found here: http://opsinimaging.com/dl/_1010492.RW2.zip . I'll post the resulting neutral coordinates that will allow others to UniWB their GH2s (assuming GH2 sensors are relatively similar).

Thanks,

Michael