scantools - a few tools to help with film scanning

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Ted Baker

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I have been writing some software to help with film scanning to to the following:

1. Speed up flat bed scanning, so a full platen of negatives can be scanned in 1 pass. So for example I can scan 24 35mm frames in 10 minutes at 2400dpi, on my old Epson 4990.

2. Software to invert both B&W and colour negatives, using the same method that is used in Cineon/DPX. i.e. just about any movie you see that was shot on film in the last twenty years.

It is an open source project so free to use and extend etc. Some of colour code needs some revamping, but I am using it to good effect for my current B&W work.

For a B&W negative the result is roughly what would be printed in grade 00 paper, so I find it a good starting point.
A colour negative results in low contrast image, that should only require a contrast adjustment and some linear colour balancing.

It in its current form it probably only usable if you have some basic programming/development skills, you need a bash shell and Imagemagick. PM me if you need some help, but it is a start.

https://github.com/laurencelumi/scantools
 

MattKing

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Looks interesting.
I'd be careful with the name though - it looks like it is already in use in the auto diagnostic field.
 

Eric Rose

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I can understand why you would get a low contrast image. In the world of motion pictures colour grading is always done to suit the directors vision. You would want to start off with a low contrast image.
 
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Ted Baker

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I can understand why you would get a low contrast image. In the world of motion pictures colour grading is always done to suit the directors vision. You would want to start off with a low contrast image.

Perhaps but there are other reasons, from a technical point of view the contrast equals a gamma of 1 so the lighting ratios in an image should be same as in the scene. This is fairest from a storage perspective because any increase in contrast in a section of the tonal scale requires compression in another. Also many computations need to be done in a linear colorspace to be correct. A DSLR works similarly at the level of RAW processing as the data represents linear intensity ratios.

So you can think of this as a kind a raw scan for negatives, which is part of what the DPX/Cineon system is about.
 
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Ted Baker

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I finished an update, that increases the reliability of the auto cropping of a full platen of film from a flatbed. So that only a single pass of a flatbed is required.
For example the following raw scan from my old Epson 4990, scanned so that there is gamma of 1

kodak400.jpg

Can be processed with the following example commands:

#scantool frames kodak400.tif output_directory
this results in 24 raw scans

#scantool both -fb 0.4196,0.2745,0.2039 kodak400.jpg output_dir
this result in 24 inverted scans that have a gamma of 1,

This is also works for reliably for roll film
 
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