How to Invert Colour Film Negatives in Photoshop

Using Replicable Equalization Technique

5 min read by Dmitri.
Published on May 31, 2021. Updated on October 24, 2024.

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This guide will demonstrate and explain a simple, reliable method for making high-quality positives from scanned colour film negatives.

There are three steps. The first two list the precise instructions for obtaining an optimal amount of visual data to create an equalized positive. The final step is colour correction.

In this guide: Tools and materials. Invert the image: Negate. Remove noise: Equalize. Colour correct. Notes for Adobe Lightroom. Support this blog & get premium features with GOLD memberships!

Tools and materials.

In the example below, I am using Adobe Photoshop 2021. However, this method is transferrable to other image processing software, like Lightroom, Gimp, ImageMagick, etc.

This method will work with RAW files, TIFFs, JPEGs or any file types, sizes, and qualities. For best results, I recommend using high-bit-depth images.

Download my sample film scan off PrimeFilm XA to follow along as I edit it below:

➜ Free Download: Sample uncompressed 48-bit 35mm Film Scan (TIFF)

Invert the image: Negate.

Let’s begin with the simplest and most straightforward step in this process. Load up your negative scan into Photoshop and create a new Invert adjustment layer (fig. 1 — A).

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Figure 1: Add an Invert adjustment layer (A). It will create a layer on top of your scan that you can edit non-destructively (B).

✪ Note 1: Creating a layer on top of your scanned negative, as opposed to editing the image layer itself, ensures that there’s minimal loss of quality in your final image. This technique is called non-destructive editing.

✪ Note 2: You will need to use a different technique to invert colours if you use Lightroom or Camera RAW.

At this point, you will likely notice a strong blue cast on top of your image. This effect will depend to various degrees on your exposure, film type, and scanning device type. Essentially, you’re seeing the film’s orange mask, but it is now the opposite of orange — blue. We will work on fixing that next.

Remove noise: Equalize.

Time to create a usable image out of your scan: an equalized positive.

Create a new Curves adjustment layer (fig. 2 — A), and select the Blue colour channel (fig 2. — B). Have a look at its histogram (fig. 2 — C).

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Figure 2: The Curves adjustment layer (A) lets you select the Blue colour channel (B) that shows empty spaces on the histogram (C).

In my image, the histogram for the Blue colour channel shows empty spaces to the left and the right (fig. 2 — C). We need to equalize our distribution of blue tones to ensure that the fringe tones of our scan align with the min/max of the channel space. The same should also be done to Red and Green colour channels.

To equalize the distribution of the individual Red, Green, and Blue channels’ tones in your image, drag the handles underneath the Curves to align with the outer fringes of the histograms (fig. 3 — A). Then, switch to the next colour channel and repeat (fig 2. — B → fig. 3 — B, C):

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Figure 3: Equalize tone distribution across colour channels by moving the dark min and light max sliders so that they touch the edges of each histogram (A, B, C).

This completes the essential, repeatable part of inverting colour film negatives in Photoshop. For some scans, this is enough, but in some cases, you may still have a blue cast or unnatural colours in your image. We will work on fixing that next.

Use Photoshop Levels (or a similar tool) to equalize your scans by moving the dark min and light max sliders so that they touch the edges of each colour channel’s histogram.

✪ Note 3: You can use Photoshop’s Levels adjustment layer to equalize your colour channels the same way you did with Curves.

✪ Note 4: See the histogram equalization caveats (below) for when your scan has a border or images of certain qualities.

Colour correct.

Your colour correction objectives and tools may differ from mine. Or you may decide that your image looks as good as it needs to be — in which case, you are done.

For a detailed guide on colour correction and advanced edits, including fixes for issues you may have with histogram equalization see this guide: “How to Edit Film Scans: Bring the Best Out of Your Film.”

Notes for Adobe Lightroom.

Adobe Lightroom and Adobe Camera raw do not have a tool to invert image colours. Instead, you can achieve the same effect by moving the bottom-left point of your colour channel (A) curve up and the top-right point of your colour channel (B) down.

Inverting image colours using curves in Adobe Lightroom.

Do this while simultaneously moving those points to your histogram’s left and right edges.

For further colour correction, I found the Color Grading tool helpful. However, you can also change your colour balance by altering the shapes of your Curves or via any other Lightroom tool you’re comfortable with.

For impeccable results, I recommend doing further research on colour correction as it’s beyond the scope of this article.

❤ By the way: Please consider making your Adobe Photoshop license purchase using this link so that this website may get a small percentage of that sale — at no extra charge for you — thanks!

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Tools and materials.

Invert the image: Negate.

Remove noise: Equalize.

About this article:

Dmitri