Sunday, September 12, 2010

Fun With B&W Film - How To Do HDR From A Single Scan

Fun With Scanning 30 Year Old B&W Film - Single Scan HDR
Right side is a special colour scan of a B&W negative, the middle is a normal scan plus some dodging and burning. The right-side is a HDR image obtained with the 48bit colour left-side image. The right side is scanned in 48 bit colours where the individual RGB channels are adjusted for gain, offset and gamma via the histograms utilizing the epson software prior to scanning in this case the green channel is normal exposure the red is -1.5 stops under exposed and the blue is +1.5 over exposed. After the scan the RGB channels can be manipulated as a colour image or separated into 3 monochrome channels. You can then  process as a colour image or alternatively as an HDR or with tone mapping software. Or as I mostly do you could keep it as a toned image or convert it back to B&W.

This being 30 years old Kodak Plus-X it does not have nearly the dynamic range of that of most fresh films such as tmax would have.
Fun With Scanning 30 Year Old B&W Film - Single Scan HDR
RGB channels are actually B&W tinted for visualization purposes only

The Ghost That Walks Beside Us
The Ghost That Walks Beside Us is a direct manipulation of a 3 channel B&W scan

Casa Loma Stables - The gold tones are because of the scan RGB gains of (1.5,0,-1.5) The reverse of the blue tint above.
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