Because film can have different thicknesses, scanners must focus on the grain to produce the sharpest images . Many modern film scanners attempt to circumvent this requirement by using a small aperture that increases the lens’ depth of field . Unfortunately, this can introduce diffraction and thus sub-optimal results.
An example of a dedicated film scanner that can focus on film grain is PrimeFilm XAs . There are also vintage film scanners like Nikon CoolScan 5000ED (which I use for this tutorial) that focus on grain and have a great lens. If you are scanning with a digital camera, you will also be able to focus on the film grain — however, you will need to be acutely aware of the angle of view as even the slightest departure from the perfect 90° can throw part of your image out of focus.
Film scanners operate like macro lenses, which means they have a very shallow depth of field, even with small apertures. So, in addition to film thickness and lens angle, film’s curvature is another factor that can cause blurry images. Good film holders will keep film mostly flat — although they may still not do that perfectly.
Interpolation is another often misunderstood but fairly simple concept when it comes to scanning resolution. While it’s easiest to think of pixels as square-shaped dots, they aren’t necessarily equal on all sides for scanners. PrimeFilm XAs, for example, uses a sensor with double the resolution in one of its dimensions. When it scans a square-inch-sized piece of film in its finest resolution, the image it produces would be 5,000 × 10,000 pixels, which looks squished until the software stretches it to 10,000 × 10,000. Of course, interpolated 5,000 × 10,000 images aren’t as detailed as native 10,000 × 10,000 ones — but they are more detailed than 5,000 × 5,000.
Some scanners have greater resolution in one of the dimensions (left), which produces squished image scans (middle). These images can then be stretched to produce a normal aspect ratio image (right).
Bit depth determines how fine the gradient transitions can be in a digital image. Insufficient bit depth becomes obvious when you try to manipulate contrast in scenes with sweeping gradients, such as the sky — it will appear as noticeable steps or lines as the colours transition. These artifacts are difficult to fix. TIFF and RAW film scans with 16-bit per channel or 48-bit total will make edits the easiest. All JPEG scans will have 8-bit per channel or 24 in total; this can still be acceptable for most situations but not ideal if you need to make significant changes to your image.
An illustration of difference between higher and lower bit depths. Note the abrupt changes in gradient continuity on a lower bit depth stripe. These changes become more apparent if contrast is altered.
Image compression. JPEG and a few other image formats can be very small compared to TIFFs and RAWs; however, that comes at a price. If you zoom in to detail on some of them, particularly if there’s a lot of red colour, you’ll see that numerous pixels can morph into a single block. This may not always be noticeable but can become an issue if you’re planning to crop or enlarge your image.
DMax is a number that usually caps at around 4.5, which represents your scanner’s ability to peer through the densest parts of your negatives. The higher this number is, the more detail your scanner can gather from the highlights (or shadows if you’re scanning slide film). It’s comparable to the dynamic range of film and image sensors.
So, what should you aim for with the scans? The beauty of film is that the best-resolving image will always be the one in the emulsion, sleeved in your archive folder. You can always return to your favourite frames with a better scanner down the line. There’s no need to seek the highest resolution if you’re only planning to post on social media for small screens. In fact, your scanner’s maximum resolution may take you longer to scan and take up unnecessary space on your disk. However, higher bit depth, less compression, and higher DMax will help you make more aggressive edits without losing image quality down the line. As for pixel density, see this guide on the most appropriate scan resolutions (DPI) for various purposes.
If you are working with a lab, you can ask them to give you “flat” scans , which typically means they’ll apply fewer changes to image contrast and saturation. While some image formats (like DNG/RAW) come with an “undo” function for all the edits, most can only save destructive edits . This means that if your lab bumped that contrast for you, some image information is destroyed; you can reduce the contrast after the fact, but certain details will no longer be there in the shadows and highlights:
This is an extreme example of destructive contrast and saturation applied to the image (middle). Attempts to correct those edits (right) may create a resemblance of the initial image (left); however, details like clouds and delicate shades in tree tops disappear (compare pink circles).
High-resolution sample scan download. As I’ve mentioned above, you can improve the appearance of your photograph with edits no matter the quality at which it’s been scanned. You can even edit scans you made with your phone. However, a high-resolution scan can make the job much easier and open up some new possibilities.
Please feel free to use this 10.6MP 48-bit uncompressed scan I made with my Nikon CoolScan 5000ED dedicated film scanner to follow along as I explain the concepts below (but you’re welcome to practice on your scans, too!)
➜ Download : Sample scan (4000px × 2651px 68MB TIFF — zipped).
You can find more sample scans here bonus sample scan here
Manually inverting film negatives. As mentioned above, edits to your scans are typically destructive. What’s more, the software that automatically inverts your film negatives is applying edits, which are often unknown in their nature and are usually destructive.
Editing poor film scans or previously altered scans, like the ones delivered by your lab or automatically converted by the software, is not necessarily an issue. But if you have an opportunity to control the entire process, you will preserve more image data and have greater flexibility in what you can do with your scans.
Note that it’s often easier to manually invert film negatives produced by a dedicated film scanner . Digital camera scans may require more involved colour correction — though it is still possible. Feel free to use tools you’re most comfortable with for inverting your negatives (or your lab scans) if you find this step particularly difficult.
To invert a negative manually, you’ll need to scan it as “slide film” — that is, with all the built-in scanner inversion settings turned off. However, you may still want to let your scanner set the exposure and focus (if available) automatically while zeroing out all the corrections.
Digital negative, shot on Fujifilm 200 with Pentax K1000 and scanned with Nikon Super CoolScan 5000ED.
Removing colour casts with histogram equalization. Film negatives will almost always render base fog (that is, the most transparent part of the film will typically have some tint), and colour negatives will have an orange mask . The orange mask will appear as a blue cast once inverted, which you can correct using a technique called histogram equalization.
Histogram equalization involves cutting the unused colour space on both sides of a histogram for each individual channel: red, green, and blue. This gets the software to stretch all the usable image data in each channel to the entire bit depth of an image, thus ensuring that visible image data occupies the same space.
The process of histogram equalization involves moving the input/output sliders near the edges of the histogram for each channel.
You can perform histogram equalization via histogram or curve tools by selecting each of the red, green, and blue channels individually and then adjusting the input/output sliders to match the edges of the histogram graph , as illustrated.
For best results, you should crop your image to include just the frame (no borders) before applying histogram equalization. This will ensure that no parts outside of your image will influence your histograms. Excluding film borders will help you avoid issues with photos that are over-exposed (since pure blacks inside your over-exposed images will not match the pure blacks of unexposed film borders).
Cropping frame borders ensures a more accurate histogram equalization process. The histogram on the left (where the scan is uncropped) includes more blue cast than the one on the right (where it’s applied to a cropped scan).
Histogram equalization is a simple technique that can help you do more than just invert your film negatives. You can use it to remove colour casts from expired film scans (including slide film scans), or film that was improperly inverted by the software. Ultimately, histogram equalization will turn the darkest and lightest pixels of your image into pure black and white.
Histogram equalization can remove colour cast or fix faded colours on expired film (including slide film). This is a ~20-year expired Provia 400 before (left) and after (right) histogram equalization was applied.
An exception to the histogram equalization technique is photographs that should not have pure black or white points. An example of such a photograph is a photo of a pure blue sky (yellow/orange sunsets can occasionally be an issue as well). If you apply the histogram equalization method, it will compress the colours unnecessarily (i.e., it will make dark blues black and light blues white), making the photo appear overly saturated. Because many film-negative inversion tools use the same method, you may notice that scans of blue skies inverted automatically may have the same issue.
An easy fix to this exception would be to perform histogram equalization on a neighbouring film frame (better yet, a frame on the same roll, shot in a similar light) and then copy those settings to the problem photo.
Note that histogram equalization may or may not fix all colour casts in your photograph (this will depend on your exposure, the type of film, and how the film was scanned). The next section will explain how to correct those additional casts.
A photograph of a small airplane in the sky has insufficient white and black points to equalize the histogram correctly for this image (left). Copying the histogram input/output points from a neighbouring frame on the same roll can resolve this issue (right).
Correcting the white balance with the help of a reference greyscale mask. Whereas histogram equalization may set your blacks black and whites white, there may still be issues with colour balance between those extremes.
Correcting the white balance involves ensuring that grey shades retain their expected hue across all levels of image brightness. This can be difficult to do as our eyes quickly adjust to changes in colour, and computer monitors also differ in how they render their available gamut. But there’s a trick you can perform to find your reference:
Find parts of your image that you know should be grey, white or black, and temporarily make half of those parts black-and-white. In Photoshop, you can do this by selecting a part of an image and then applying a Black & White Adjustment Layer, which will be masked to that selection, as illustrated:
Correcting the white balance across the entire image luminance levels (highlights, mids, and shadows) with the help of a temporary greyscale image mask. Ensure that your greyscale mask is *on top* of your colour balance layer.
You can now use your favourite colour grading tool to change the colour balance in the shadows/mids/highlights of your image (you can even use the curves tool) to match your image’s greys to the actual greys of your reference slice. My favourite interface is Photoshop’s Color Balance Adjustment Layer, which I can use to alter the colours in a particular image luminance area to make my greys grey.
Lomography Color Negative 800. Hasselblad 500CM, scanned with Nikon Super CoolScan 5000ED. Notice the colour casts that make the model (@generalgreavous) and the black jacket appear red or blue — the grey reference mask will not work here.
Colour grading, colour balance, and curves tools will not let you limit your adjustments to a specific luminance perfectly. If your scan has severe colour casts, you may not be able to fix it entirely. For example, a photo taken on a daylight-balanced colour-negative film (read: most colour-negative film) under yellow indoor light will often yield a strong green cast, which can be impossible to counter across the entire image: correcting it in the shadows may turn your mids purple, and there could be no way to ensure that all luminance levels remain properly balanced. Similar problems may arise in mixed light, where parts of your image may have different colour casts.
Also, note that colour correction settings can not be blanket-applied across the entire roll of film without some tweaks (even if you have a photo of a colour reference card on your film roll). Any minute change to ambient colour temperature or exposure will require adjustments, which is why software that promises automatic “roll analysis” rarely yields perfect results.
Note about using the grey reference mask method: materials that we know are grey aren’t always perfectly grey in the real world. Coloured light, such as yellow sunsets, light that becomes coloured due to reflections (i.e., sunlight reflected from water), and coloured gels (see the photo above) are supposed to change the colours of the greys. Thus, you should keep this in mind and consider applying your edits with your memory of the scene in mind.
Blending colour correction layers. I try to avoid this technique as much as possible. It’s time-consuming, and it can make scans look unnatural. But sometimes, there’s an image that I need to tell a story, and there’s no option to remake it.
If you find that your colour corrections fix a part of your image while causing problems in the other, you can try masking your changes and blending multiple colour-corrective layers across your scene.
Green casts caused by indoor lighting on daylight-balanced films can be challenging to fix. Though panels 2 & 3 look decent on first look, consider the colour of the side table that turns red instead of the natural yellow bamboo and how fixing the excessive blue in the pillow and the dog bed areas adds even more red to the table and colours the tiny dog’s bed green again. Blending corrections may help here, but that intervention will have limited success as the film (Pro Image 100) does not have sufficient colour information registered.
Changes to hue and saturation. Different colour film stocks will offer various saturation levels. For example, Harman Phoenix 200 and Kodak Ektar 100 produce some of the most saturated images on the market, whereas ORWO NC500 is notoriously under-saturated.
Furthermore, scanners differ in how they render saturation (which may depend on the sensor, firmware, and scanning lens). The way the film was developed also matters: pushing colour film will often increase saturation, whereas pulling will do the opposite. And so does your monitor: one screen may show more saturation, whereas another can show less — even if it’s the same image!
ORWO Wolfen NC 500 with Voigtländer Vitessa A in warm sunlight. Scanned with PrimeFilm XAs as a digital negative, inverted by hand in Photoshop. +28 Saturation in Photoshop (left) vs. no adjustments (right).
I find that automatic negative inversion software and labs tend to increase the saturation of the film scans. Generally, that’s not a problem. However, doing so can sometimes create unrealistic expectations from film stock, make it look cheap when applied excessively (IMO), and cause loss of detail — particularly in the red channel, which has the most trouble with JPEG compression.
There’s no limit to what you can do to your film creatively, and the advantage of going through manual inversion and colour correction steps, as described above, is that you will know whether it’s your film that’s saturated or if it’s the software that did that. Still, I like to reserve these kinds of edits to the few scenes that absolutely require it. Well-scanned, well-corrected films usually look sufficiently saturated; pushing film, finding more colourful stocks, and, most importantly, finding a light that brings out greater saturation naturally are the best ways to produce saturated images without sacrificing integrity and the encoded image information.
Fine-tuning contrast and exposure. Many photographers prefer black-and-white film to colour film for simplicity when scanning: no colour correction is needed. However, black-and-white film scans may still need histogram equalization, and they can also be creatively manipulated for contrast.
Contrast adjustments with Kodak Aerochrome film.
You can selectively manipulate contrast in various luminance levels of your black-and-white films — but you should also be aware that, depending on the scan and the film that you are scanning, significant changes can increase the film’s apparent graininess. The quality of this grain may not always look pleasing, especially in the highlights and shadows, where the loss of image quality may be most apparent.
Colour images may also have their contrast levels adjusted. I recommend creating a new adjustment layer in addition to your colour corrections.
Whereas contrast adjustments are made by making an “S” curve (darkening the shadows and bumping up highlights), you can use the same tool to also increase apparent or decrease brightness across the entire image by moving a single point on the curve. Or, you can combine the two by manipulating contrast in some areas while also changing the overall brightness.
Cleaning up dust & scratches. Refer to this guide
A few extra tips:
In Photoshop (and maybe other apps), there are various modes for the healing brushes. “Content-Aware” is likely the most useful one; however, it’s not great at removing spots in areas with localized gradients (like round objects) — this is when I would switch to the “Proximity Match” mode.
You can use larger brushes on big, empty areas like the sky, but you will need to be more precise with a smaller brush in areas with lots of fine details.
You may get different results when “dabbing” with the healing brushes rather than applying long strokes.
Cleaning up dust and scratches may take some time and effort but it can improve the quality of your scan by removing distracting elements.
Sharpening film scans. Not all film scans have sufficient grain sharpness, and the image itself may appear a little soft. This is why many labs and even home scanner software will automatically add sharpness to your scans.
I tend to avoid sharpening as I’m often happy with the quality of my scans. Besides, it can make the grain appear chunkier than it needs to be (more on that later). However, there are times when more details need to be shown and sharpening is an easier way to do that than to re-take the photo and/or find a better scanner.
Digital sharpening works by increasing contrast in small, localized areas tiled across the image. This is why many sharpening tools have separate controls for radius and strength. Radius refers to the size of the localized areas, whereas strength is the amount of contrast.
To find an ideal amount of sharpening for your image, increase the “Amount” to maximum and then play around with the “Radius” until it adds a sufficient amount of sharpness while avoiding halos around them. Then, decrease the “Amount” to the absolute minimum you’re willing to accept so that your image looks natural and the grain stays in check.
An easy way to determine the minimum necessary amount of sharpening is to start by setting a high strength value — much higher than what you’d expect from a final result — and then adjust the radius. A small radius of 1px-7px (the precise values depend on the resolution of your scan and the graininess of your film) will mostly increase the prominence of your grain and perhaps the thinnest lines, like thin hair. A larger radius can make fonts more readable, and larger details stand out better.
Once you’ve figured out what sharpening radius helps you add detail to the parts of your image that need it best, decrease the strength to the minimum value you are willing to accept. You can toggle to sharpened/not sharpened results to find a balance that shows the least amount of added noise while also a satisfactory increase in detail levels.
The process of finishing an image (right) which involved a few attempts at cropping, perspective correction, colour correction, and a bump in vibrance to create a pastel or an “Accidentally Wes Anderson” feel.
Cropping and perspective correction. If you’re looking to create planimetric staging and don’t have access to scaffolding if your lens distorts the image or is too wide for the cleanest, most important part to stand out, you’ll need to adjust your perspective or crop your image.
Higher-resolution scans and larger film formats allow for more aggressive crops and perspective adjustments, but either format is acceptable.
While cropping and making perspective corrections, apply the same composition principles as when you shoot your photos . I recommend using vertical and horizontal guides to aid your perspective and lens curvature adjustments.
In most cases, film grain will not be visibly stretched with perspective corrections or lens curvature corrections. However, you should be mindful that applying such edits will increase its relative size and decrease the image resolution.
How to avoid image data/quality loss. Applying edits or colour corrections to your scans (aside from inversion and histogram equalization) causes a loss of quality.
The greater the resolution, dynamic range (DMax), and bit-depth of your scans, the more quality you can afford to lose. If your images are meant to be shown on a small screen or printed small, some quality loss won’t be apparent at all (the reverse is true for larger prints/displays).
I’ve edited scans as downsized JPEG images destructively multiple times and got good, printable results (but there are also cases when I worked with uncompressed TIFF scans and still caused issues during edits; thin negatives, expired film, and incorrect exposures may be very difficult to fix without noticeable loss of quality ).
Consider the size and the quality of your final images. If you can spot issues (like missing detail in shadows/highlights), try dialling back some of your edits. If your resources are limited, you may need to find a balance between showing artifacts and lacking correction. Remember that your time is also valuable, and thus, if you can’t make your scan look right after an hour spent with edits, it may never look right.
