Action: Convert colour negative to positive

[photoken]

Here's an action to convert a colour negative into a colour positive. It makes use of an old Photoshop trick to remove a colour cast from an image.* The action will be attached to the next post.

To use the action, first crop away the film edges and borders (if any) so that the Blur...Calculate Average function is not skewed by the sprocket holes:

colour negative cropping.png

then run the action. The only input you will have to make will be when the action pauses and displays the Curves adjustment dialog. Because the Curves dialog uses the last settings, you need to use the Gray Point eyedropper to click in the "before" area at the left of the dialog's preview area:

colour negative curves.png

That's it! The action will proceed to flatten the image, invert the colours, and apply an automatic Histogram correction to the resulting image to yield this:

colour negative final.png

Enjoy!

__________
* The Photoshop trick to remove a colour cast is as follows:
1. Duplicate the image.
2. Apply a Blur...Calculate Average to the duplicated image.
3. Add a Curves adjustment layer above that averaged, duplicated image.
4. Use the Gray Point eyedropper in the Curves layer to set the averaged image to a medium gray.
5. Hide (or delete) that averaged, duplicated layer so the Curves adjustment layer now is applied to the original image.

[photoken]

And this is the action:

Colour Negative to Positive.actions

[Herbert123]

Thanks! One comment about that colour cast removal trick: it will not work on all images.
For example, this one:
http://1.bp.blogspot.com/_rZNj4rQyCn8/S ... 00/001.jpg

Which causes the "trick" to fail completely.

[photoken]

Thanks! One comment about that colour cast removal trick: it will not work on all images.
For example, this one:
http://1.bp.blogspot.com/_rZNj4rQyCn8/S ... 00/001.jpg

Which causes the "trick" to fail completely.

Although I have found some samples on the Web where the "trick" doesn't completely remove the colour cast, with your sample image it works well:

cc 01.png

Note: I first cropped the image to remove the white border and the shadow. It's important to have only the actual image content without any other areas that might skew the results of the Calculate Average.

[Herbert123]

Ah, my mistake - I used the wrong eye dropper, which caused the image to go bonkers.

I couldn't resist, and tried some other images. It's a bit of a hit and miss method for me. Some work quite well, others... not so well at all. It very much depends on the type of photo and the lighting conditions. For example, with this image the result is quite funky:

zebras.jpg

Result:

Untitled.jpg

Yes, it got rid of the colour cast, but is it better?
Main reason I do all my image correction and enhancement manually.

Still, an interesting method and quick one for certain photos that I had not encountered before. Thanks!

[photoken]

I couldn't resist, and tried some other images. It's a bit of a hit and miss method for me. Some work quite well, others... not so well at all.

Yeah, it's addictive....

You're absolutely right about it not working for all images. It seems to work best for images that have an overall colour cast that's the result of fading or scanning problems, etc. Even with your last example, it might serve as a starting point for manual correction. Still, it's useful enough for me to have an action for it.