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Lightroom and negatives
Old 10-11-2018   #1
wintoid
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Lightroom and negatives

Many of us film shooters are copying our negatives using digital cameras. Unfortunately, Lightroom doesn't contain an invert function to make a negative positive, and setting the curves to invert the image results in the sliders all working back-to-front. So I wanted a solution. I'm an ex-software guy, and currently using a Mac for my photo stuff. I'm offering the information about how I process negatives to positives, in the hope that it will help others. I'm probably not up for providing masses of support if anyone tries doing it my way. This is probably for the more geeky Mac user, if there is such a thing.

Summary of method:

I've written two bash scripts to control Imagemagick, which can produce inverted TIF files from camera raw files (in my case Sony ARW files). You CD to the directory containing your ARW files, and run ~/process_all_negs to produce TIF files that match the ARW files in the same directory.

Pre-requisites:

Macintosh
Homebrew installed (see https://brew.sh/ )
Imagemagick brew installed (see http://brewformulas.org/Imagemagick )

The first script, I call process_one_neg and the source looks like this:

Code:
  file=$1
  outputfile="$(basename "$file" .ARW).TIF"

  echo $file started $(date)
  convert -contrast-stretch 0.25x1% -negate -colorspace Gray $file $outputfile
  echo $file finished $(date)
The second script, I call process_all_negs and the source looks like this:

Code:
ls ./*.ARW | xargs -P 8 -n 1 ~/process_one_neg
I put both these scripts into my home directory on the Mac, and chmod them to be executable.

Things you might need to change:

The code above is for ARW files. If your camera makes a different type of raw file, you will need to change ARW to be that file type.
The setting "-P 8" in process_all_negs makes the computer use 8 simultaneous threads, because the CPU in my Mac has 8 threads. If your processor has more/less, you may like to change this setting.

I hope someone else finds this useful. It works well for me, and has allowed me to keep using Lightroom. Needless to say, you should use at your own risk.
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Old 10-11-2018   #2
Steve M.
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You mean to tell me that an image editing program that costs $120 a year doesn't have an "invert image" option??? Wow, what a crummy deal. Really dumb way to design an image editing program, but I'm sure it was done on purpose in order to extract more money from its victims, oops, I mean customers. Nothing Adobe does surprises me anymore. I won't pay those shysters one thin dime because there are lots and lots of free image editing programs out there. I've been using a free unregistered version of PS 7 for years and years, and it does way more than I need for B&W or colour film.

Speaking of that, couldn't you just download a free image editing program such as GIMP or something to get that feature, invert your neg with one mouse click, then send it to Lightroom? Shoot, even my scanner software used to offer an "invert image" option.
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Old 10-11-2018   #3
Scapevision
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It does, all you have to do is switch to point curve and drag lower left point up, and upper right, down. Sliders will work backwards though.
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Old 10-11-2018   #4
lamefrog
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@wintoid .. Thanks for sharing . This is useful . I prefer working on the command line as much as possible as well and I also use ImageMagick, mainly for resizing and adding borders/matting before export. I also have a bunch of scripts that access the Lr database from the command line for extracting information (labels, keywords , other metadata etc)
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Old 10-11-2018   #5
brbo
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Quote:
Originally Posted by Steve M. View Post
You mean to tell me that an image editing program that costs $120 a year doesn't have an "invert image" option???

Speaking of that, couldn't you just download a free image editing program such as GIMP or something to get that feature, invert your neg with one mouse click, then send it to Lightroom? Shoot, even my scanner software used to offer an "invert image" option.
$120-per-year Adobe Photography plan comes with Lightroom AND Photoshop. No need for Gimp and, yes, Photoshop does have a one-click option for inverting the image*.


* Not very usable for inverting negative scans, but neither is Gimp's
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Old 10-12-2018   #6
willie_901
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Quote:
Originally Posted by Steve M. View Post
You mean to tell me that an image editing program that costs $120 a year doesn't have an "invert image" option??? Wow, what a crummy deal.
Not exactly. LR CC Classic includes Photoshop. One can conveniently use PS as a plug-in and invert negatives. One advantage of this is it is possible to use different Actions for different films. Also, inversion Actions can be licensed form numerous third-party sources.
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