How to Scan and Edit Film Without Changing Its Look

The opaque nature of scanning software is making some people think there’s no useful difference between film stocks other than their grain size. After all, what’s stopping you from editing your Portra 160 to look like Kodak Ektar or Tri-X in Photoshop?

Besides, scanning software automatically processes negatives, changing their “look” — maybe to the point of lost recognition.

Knowing this can make comparing films and digesting film reviews seem like a confusing, futile pursuit.

This guide will show you a few proven ways to preserve your film’s colours and saturation during the scanning process.

What can alter your film’s “look”?

— Reddit.

Most photographers’ queries about minimizing edits and preserving the film’s “look” are met with a non-answer. Some say it shouldn’t even be attempted: “all negatives must be altered via conversion to positives, and their colours/contrast must be interpreted.” Others point to the numerous alterations an image must go through as it’s converted from a negative to a positive:

1) Your scanner’s lamp, optics, sensor, and driver will affect the negative’s colours/contrast.

2) Your computer’s operating system and graphics card will use colour calibration algorithms that are not consistent across devices.

3) Your display calibration, type, settings, and ambient light will strongly affect the colour temperature, fidelity, saturation, and contrast.

4) Depending on how your image is stored, various compression algorithms will change the colours and the fidelity of your photographs.

5) Printer type, settings, and paper — if printing digitally — plus the chemicals, temperature, water impurities, and filter choices if printing in a darkroom.

6) And finally, your edits.

These inevitable alterations aren’t new. Photographers have always had to deal with #5 and, for the most part, #1 in a darkroom or by a minilab machine. Although, that’s not universally true:

Daguerreotypes, images produced using the first commercially available photographic process, are metal plate positives that can be framed and considered a finished product.

But we don’t have to look that far back: modern slide films, such as Fujichrome Velvia 50, yield pictures with all the properties of a final photograph. You could frame and hang your slides, though doing so isn’t as practical as with digital or print slide enlargements.

When it comes to negative film, there are indeed numerous obstacles to extracting images with minimal influence or distortions along the way. Still, this type of quest isn’t new: just ask an audiophile about all the expensive ways sound is amplified with minimal noise or a scientist looking to get the clearest picture from an instrument. Of course, not all changes to the signal are “noise.” My point is that minimizing the changes to colour and contrast during the scanning process is possible.

Scanning slide film to match its intended colours and contrast.

Your scanner and the software that runs it will interpret and alter the likeness of your slide film. But with the prototype in hand, you can correct those distortions with your own edits.

If you’re using Photoshop or Lightroom, you may tweak colour balance or make more drastic changes by altering contrast curves for each channel until what you see on the screen matches your film’s colour on a light table. This can even work with your lab’s scans.

An even better way would be to process scanner output manually:

1) Create a digital negative.

2) Equalize its histogram to get a flat, fog-free scan. This method removes most of the automatic corrections done by the software that may be changing the look of your scan to look less like the original.

3) You may still need to adjust the colour balance and brightness, though it should be less work than trying to fight your scanner’s automatic image processing alterations.

⚠️​ Warning: Histogram equalization may cause issues in images with ambiguous white/black points. An example of such a photograph is deep sunset when the brightest part of your sky is yellow (not white); histogram equalization will attempt to turn that colour white.

Histogram equalization also corrects colour casts caused by expired chemistry and improper storage. Because of that, you may get a more accurate/diverging colour than your slide film master.

Scanning black and white/clear-base negatives to match their intended colours and contrast.

Black and white film is the simplest negative to scan without altering its intended contrast curve. There are just two steps:

1) Create a digital negative.

2) Invert the image (negate).

3) Equalize its histogram to get a flat, fog-free scan.

These steps work for all clear-base negative films. (All black and white film is clear-base, but only some colour films are clear-base).

As with slide film, this method “decodes” your black-and-white negative into a positive without any need for interpretation. The contrast levels that you get are a direct reflection of the manufacturer’s design (with some bias added by your scanner’s drivers, OS, and hardware).

All methods involving a scanner, hardware and drivers distort the image, and there’s nothing that we can do about it. Thankfully, this effect is minimal as those tools are built specifically to reproduce colour accurately. On the other hand, software that inverts negatives makes drastic changes to the image based on complex, proprietary algorithms. This type of software is tuned for visually-pleasing results from colour films with an orange mask — not accuracy, and not standards. These algorithms typically work by analyzing the input and making colour corrections based on a set of rules or a machine-learned model.

But unlike orange-masked films, clear-base emulsions can be cross-processed to yield a “true” positive. Inverting such films digitally is equivalent to cross-processing.

Not all clear-base films are meant to be used as slide film; thus, they may show colour casts when cross-processed/inverted digitally. These casts are similar to those of expired slide films, caused by the shifted hues of the individual colour layers. This issue, along with base fog, can be corrected with histogram equalization.

Automatic colour correction tools can have issues inverting colour films with a clear base, like Kodak Aerocolor. Users report scans with a strong blue or yellow colour cast. The method described here should work better, though it will take more time, and it doesn’t correct all hardware limitations.

Scanning colour negatives with an orange mask for consistent results and editing to highlight the film’s best features.

Clear-base negatives, like slide film, can be inverted and equalized to extract an image with contrast and colours embedded in the emulsion. Using the above methods, we can create “edit-free” photographs. However, that’s not the case with C-41 emulsions with an orange mask.

An orange mask is a non-standard colour (sometimes green or blue) added to the film base to simplify and enhance the accuracy of colour chemistry. It works by offsetting the impurities in the magenta colour layer that would otherwise make it appear yellow in print; the orange mask, when inverted, “subtracts” those impurities. The same mask is used for the cyan layer’s “purification” during the inversion. This works well in a dark room where the printing paper made specifically for the task would balance the colours by using a similar principle in reverse; the printer would then set colour filters on their lamp to add final tweaks to the image.

Unfortunately, the orange mask further obscures the intended image colours to the point of having to be interpreted by the printer. This means that even after histogram equalization during scanning or printing on photographic paper, we may have to balance the colour further until we can visually confirm its quality.

Colour interpretation/final colour balance is difficult to encode into an algorithm as every film behaves differently and the results may change drastically depending on exposure/development technique. Scanner software uses complex, obscure code and various assumptions to do this job. It may keep most of your film’s built-in attributes, showing colours close to how they would appear in a good print — but there’s no guarantee it won’t apply inconsistent edits, sometimes hiding or altering your film’s properties to look like something else.

You may accept software “magic” to do the hard work of fixing colour casts. Or, you may invert your orange-masked negative by hand and correct colour casts using a Colour Balance tool in Photoshop, Lightroom, or any image-editing software.

I use this method for all my film reviews. It helps me compare film stocks confidently thanks to these reproducible inversion steps:

1) Create a digital negative.

2) Invert the image (negate).

3) Equalize its histogram to get a flat, fog-free scan.

4) Colour balance.

The fourth step is interpretative, where the settings need to be eyeballed. However, you can observe and quantify all the colour-correction work.

Oftentimes, there’s no work for #4, and the photographs may be used as a final image immediately, like those of clear-base films. But not always. Whatever the case, this method gives control over the amount and type of colour tweaks: you may add an absolute minimum to preserve most of the film’s embedded attributes while getting rid of the colour cast, or you can alter the film to look significantly different. The choice is yours.

Other times, there are more colour and contrast adjustments to follow, along with sharpening and cleaning up dust/scratches.

How much should you edit your film after scanning?

Minimal/no-edit methods described in this article are particularly useful for film reviews. But they aren’t always the right choice when it comes to photography.

Your or your lab’s scanner software (either with default or custom settings) may be a sufficient, fast way to get good images without spending too much time at the computer.

Photo editing may be a major part of your process. Some pieces may involve more time and resources during the editing process than with a camera — there’s certainly value in that approach.

While the process and the medium can be of great importance to you, it does not inherently make better or worse art.