How do you convert a negative digital image to a positive?

See this post of Léonie in the thread B&W negatives to positive photos.

This should be simple using the free-ware GIMP. Inversion is not a function Aperture performs.

Just for fun, you can easily invert your whole computing environment: "{Control}+{Option}+{Command}+8". If you need to visually check an inverted Image, this is the quickest way to do it.

What a bizarre keyboard shortcut! I wonder why Apple decided to put that feature into the OS... Yes it's good for checking negatives, but wow. Never encountered an OS feature quite like that before.

nathan

Its part of Universal Access. Doing that can be a benefit to certain vision problems.

GIMP will do it but Léonie came up with a way that uses the builtin bits of OS X.

And kudos to Apple for all the work they've done with assistive technology 😎 .

As I recently discovered, you actually can create a negative using Aperture 🙂, with the "Curves" controls.

• Add a "Curves"-Brick from the "Adjustments"-drop down menu,
• set the channel to RGB,
• and invert the RGB curve by dragging the left handle upward and the right handle down.

This will invert the mapping of the luminance - black to white and white to black.

Cheers

Léonie

P.S. But thanks for pointing out my quartz filter action! 🙂

BTW, Kirby, I discovered how to invert an image in Aperture as a by-product of our recent discussion on "Levels" vs. "Curves" - one of my snake charming experiments, while trying to convince you that "Curves" should not be neglected Is there any way to compress an individual color channel? (My own quick Q.)

Cheers

Léonie

I've played with that before but was hesitant to suggest it as a solution for converting a negative into a positive.

Don;t know why but it just doesn't feel like a permanent solution. 😕

Well, it is as permanent as any other revertible image adjustment in Aperture, unless you export and finalize the adjustment. 😉

But I have doubts for different reasons: To do a correct negative - positive - conversion, we would have to know the characteristic curve the scanner used, when it created the negative in the first place. My Automator action you quoted, was meant to be used with B/W negatives, so no color adjustment would have been necessary. I doubt, that a true color negative can be converted by simply inverting the luminosity curve. Probably some additional tweaking will be necessary.

Regards

Léonie

Right just looked back at the OP's post, I added the B&W part in my head, Have to stop doing those late night sessions!

I guess the real question is how did they turn into negatives and if its only a handful it might be best to re-scan them.

I added the B&W part in my head, Have to stop doing those late night sessions!

Welcome to the club, Frank! That happens to me all the time - for everything interesting in this forum seems to be happening when in Europe it is time to sleep.😁

The simplist way to a batch conversion is what i am looking for.

Then try just the Curves adjustment, I posted,

• have a look if it looks good,
• adjust one image and select it
• lift the adjustment with the Lift&Stamp tool,
• and then select all your shots that need conversion at once -
• and stamp the adjustment onto them

You can always undo this, if it is not satisfactory.

And if you (OP) want to refine that a little. Assuming that Léonie's Curves inversion is useful (it should be, but no reason to proceed if it is not). IME, a quick luminance triage prior to the batch conversion is often worth the trouble. Quickly divide your 500 Images into sub-groups by overall exposure: light, medium, dark. Produce one good inversion for each sub-group. Include, as needed, minor tweaks with the Exposure and/or Levels Bricks. Lift & Stamp per sub-group. Quickly check results. Remove temporary grouping.

The quick triage can be done with temporarily-applied ratings. Use 1-star ("1") for dark, 2-star ("2") for medium, and 3-star ("3") for light. Then filter by this rating, select all, and create Albums. After approving all the conversions, delete the Albums and reset the ratings to Un-rated ("0").

The principle here is that many optimizations are luminance-based, and it's good to create and apply them specific to the luminance-distribution of the originals.

OTOH, this may not help at all 😉 . Try any "ready-to-stamp" adjustments on a few Images with at least one from each general luminance group. If it works well, no reason to sub-divide.