No matter how gingerly you may be handling your film, the chances are that dust and scratches will creep in, especially if you’re trying to restore an old archive. There are few ways to remedy these artifacts — some are software-assisted, others are scanning device-based or mechanical.
If you know how to create layers, select brushes and resize images in Photoshop or GIMP, you should be able to follow this guide.
When and how to use automation to clean up damaged negatives.
Dust, scratches, and other kinds of film damage can be removed with variuos tools, including the Dust & Scratches tool in Photoshop. I found that it works well for images that you do not plan to print or display big and with a minimal amount of damage.
While cleaning up film by hand will typically yield much better results, it can take a long time to complete. Thus I suggest first seeing if either Photoshop’s Dust & Scratches, another tool, or your scanner’s Digital ICE software can do the trick for you.
When to use a (Spot) Healing Tool to clean up damaged negatives.
Good automatic restoration software is hard to come by. And even if you find something that works well for you, it won’t perform its best in every case. For example, Photoshop’s Dust & Scratches tool is known to blur images, remove all evidence of film grain/fine detail while failing to especially badly affected areas.
The method described involves some effort on your part, but you’ll have complete control over the image. You will be able to fix blemishes automatic removal tools fail to remedy and retain most of the fine detail and film grain in your scans.
The technique that involves using Spot Healing Tool will work on all sorts of film, unlike the Digital ICE and similar technologies that use the infrared channel to detect and fix certain imperfections on colour film only. Digital ICE is also not available for scans made with DSLR cameras.
Photoshop is a complex software, it isn’t particularly cheap, but its interface is ubiquitous enough to provide a solid example that may work with many other image editing tools, such as GIMP. The technique discussed here does not rely on any fancy filters, blending modes, or channel separations. It is simply a method of applying Photoshop’s Spot Healing Tool (or just Healing Tool in GIMP).
Download sample scan files.
You can better compare the cleaned-up version to the original scratched-up scan and practice your technique using these ready-made files ☟
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A seven-step process for removing dust and scratches from film scans using a (Spot) Healing Tool.
I’ve separated different aspects of the clean-up process into numbered subsections. You don’t have to go through them in the sequence described, but I recommend you get through the first three before anything else.
✪ Note: I will be referring to the (Spot) Healing Tool as a “brush” or a “healing brush” for brevity.
1. Set your expectations.
The more time you put into digitally restoring your negatives and the more experience you have doing so, the better they will appear in the end. It’s certainly possible to fix some scans to the point that even zooming into the pixels won’t reveal the “healing spots.” However, this method won’t restore torn film, fix areas that have way too many scratches, or do anything for your optical/darkroom prints.
You should also understand that there are some levels of damage that can not be repaired. For example, if you apply the healing brush tool too much, the quality of the fill-in textures degrades up to the point of becoming a solid colour — which is a serious loss of detail.
2. Choose your candidates.
If your film is damaged as badly as some of the examples in this article, it could take you an entire day — or longer — to clean up an entire 36 exp. roll. Thus if you have different plans, consider selecting only the important few pictures for the job (whatever your measure of importance might be).
If digitally restoring negatives is your long-term project, consider averaging your recorded clean-up time per negative and then budgeting the number of hours you plan to dedicate against the number of frames you have in the “to do” pile.
3. Consider your film size, print/display dimensions, and your audience’s viewing distance.
Now that you’ve selected your candidates, you’ll need to decide the amount of effort required for each.
How much of the dust and scratches will be noticeable to your viewers? Knowing this can save you a lot of headaches fixing tiny imperfections no one can see. Or it can prepare you for a long day of work if your project demands it. Here’s how you can determine how much of the “bad stuff” your viewers can actually see:
3-A) Determine the magnification factor for your final image. Your film format and display medium will determine the amount of enlargement that will take place once it’s “live.” For example, to display a 35mm film scan on a 12” monitor, it has to be enlarged about eight times. But a 4x5 film frame will only need to be doubled. Small scratches and dust particles will likely remain barely noticeable on large formats in this scenario, but they sure do become apparent when blown up from smaller negatives.
3-B) Simulate display resolution. If you’re scanning your film for Instagram, you may not need to worry much about dust and scratches even on 35mm film. To check, try resizing your image to be 1800 pixels wide, which is the maximum resolution that the app stores. You can use the same method of estimation for any online service: find the maximum pixel dimensions, change your scan to fit that limitation and check to see if you need to fix things up.
3-C) Print size and the viewing distance. If you are planning to print your images, you will need to consider the viewing distance of your audience in addition to the print’s size. A billboard, for example, is meant to be seen from afar and could appear in our view no larger than an Instagram post, but a wall mural printed in high resolution will reveal every bit of imperfection.
Use your knowledge of how large the image will appear to your viewers and zoom your editor’s view to approximate that size on your display periodically. Like a painter who draws each stroke up-close, you will need to “stand back” to see the whole piece as it’s meant to be seen. Use your judgement for deciding what to touch up from there.
4. Prepare your brush controller/interface.
I’ve had decent success with my Macbook Pro’s touchpad as the brush controller; a mouse may work well for you. Or, if you have one handy, a good graphics tablet that you’re familiar with could provide better comfort and reduce strain. You will need to make many fine motor movements and thus should ensure that you don’t strain your wrists — the pain could be very unpleasant and last a long time.
5. Use appropriate brush sizes.
The smaller the size of your Spot Healing Tool is and the more precisely you trace your dust particles and scratches with it, the better your results will generally look. Even the most technically advanced “Content-Aware” brush mode in Photoshop will not fill in the blemishes perfectly. Some textures creates may appear blurry, skewed, broken, or plain wrong. Minimizing the areas of computer intervention ensures that they are difficult or impossible to tell apart from the actual photograph.
However, when the image texture is non-complex, like the blue sky, which is mostly one colour, a larger brush may cope pretty well, and you will be saving a bunch of time painting broad strokes.
I typically work with brush sizes of about 10 pixels on 5000DPI film scans (see attached). That usually matches a typical scratch width for me. If the area affected is too big, I would bump the brush size up or just drag it over the damaged surface until it’s covered.
6. Alternate between continuous application and dabbing.
Healing brushes are great at filling in long scratches on plain backgrounds like a blue sky. However, once your scratch lines begin to cross complex textures and repeating patterns, the “healed” spots may not match the surroundings well.
To deal with that, leave out the part of your scratch that covers the “difficult” area of the photograph. Then resize your image to the approximate size it’ll appear to the viewers and see if that part of the scratch is still visible — I find that in many cases, busy textures obstruct some blemishes. If you deem the damage to be too great to remain, zoom back in and try to apply your Spot Healing Tool to small areas, i.e. “dab.” As you do that, undo the dabs that did not fill in well while keeping the good mini-fixes stay.
Healing brushes work by calculating the contents of a fill-in spot based on their surroundings. This happens whenever you release your mouse/finger/stylus after drawing a line. If the spot you are filling in is surrounded by dust and scratches, the brush may decide to paint a sample of those blemishes inside the area you’re trying to fix. To counter that, clean up all the easy spots around the difficult one to give your Spot Healing Tool a better sample of textures to work with.
7. Try different types of brushes.
Photoshop has Create Texture, and Proximity Match modes that you can try in places where its best and default mode, Content-Aware, isn’t working for you. GIMP has a few modes as well.
This article suggests using another approach that involves layering an auto-corrected image on top of the original, confined to the areas that need fixing, using the History Brush Tool. However, this method isn’t practical with long, severe scratches and has the disadvantage of not being able to improve fill-in textures as the surrounding areas get cleaned up.
Example 1: heavy film damage.
The following image is a monochrome slide film scan of a photograph from a family archive that dates back at least 40 years. It was rubbing against other slides in a dusty box for a very long time, and the result is rather stark: deep groves, chemical residue, lots of dust. All of this was evident as soon as I held the frame against the light and became positively disheartening when I fed it through my dedicated 35mm film scanner:
The damage is so bad here that you are likely to notice it even if you’re reading this article on a small screen (close-ups below).
Fixing this image would take a lot of effort, so before sinking my time into this, I decided to try Photoshop’s Dust & Scratches tool to see if it could do the trick. So I’ve applied the filter using Radius = 7px and Threshold = 11lvl values and added a bit of sharpening using the Smart Sharpen tool on top:
The above image may appear acceptable to you on a small screen, but looking up-close, you’ll notice that a lot of detail was lost, and many blemishes remained.
Having decided that this image deserves better, I applied the above process to create a “Human-Restored” version of the slide:
The result is a much sharper image, with lots more detail, film grain in-tact and all but the few blemishes removed. But the drawback is that this job stole 80 minutes of my time. Here are the close-ups of both methods against the original damage to give you a clearer idea of the improvements:
As you can see, no method is perfect, but up-close and even from afar, my human effort paid off in a lot more detail and more complete fixes.
Example 2: medium film damage.
What you’ve seen above is a nightmare scenario. But what if you’ve got a damaged negative that isn’t decades old and, perhaps, a little easier to work with? The following example has very straight-forward horizontal scratch lines and lacks the complexity of the first example:
Despite the big number of blemishes here, this job only took 15 minutes when done by hand with a healing brush:
This is as close to perfect as I’m willing to take it. Safe to print large, as long as you don’t mind film grain. Here’s the automatic restoration attempted by Photoshop’s Dust & Scratches tool for comparison:
Because the damage wasn’t as extensive, I was able to dial back the smoothing, but some detail is still missing, and not all of the damage is repaired with the automatic retouching.
Example 3: light film damage.
The following job took less than 5 minutes with the Spot Healing Tool. Original:
Fixed with a healing brush:
This restoration job was so quick I didn’t bother trying the automatic method as it would probably take more time and would definitely not look any better.
I would love to hear what you think of this method (on Twitter or via email) and whether you could beat my time or do a better job with the files provided here. I hope that this read gave you valuable insight into the image restoration process and some ammunition for your clean-up projects!