In this age of smartphones with incredible cameras, it is easy to take high-quality images for granted. True, we may not get the composition we want, but exposure and focus are pretty much guaranteed.
NOTE: Here’s my review of two Epson photo scanners, v600 and v850, for more technical detail.
The magic of an iPhone 16 Pro in Cambodia.
But, if you’re researching old photos for a documentary, or sorting through hundreds of older family photos, you quickly recognize that “image quality” is more loosely defined.
This past week, I’ve scanned hundreds of prints and slides from the 1950’s and 60’s. Most were taken by folks with only a cursory understanding of focus, composition or exposure. VERY cursory. Yet, all of these images are priceless and, aside from the truly blurry, we want to preserve them for both library access and a documentary.
In this tutorial, I’ll share techniques that can help improve capturing still images using a scanner, though these techniques also apply to setting grayscale levels in video.
MY GEAR
When working with still images, if the memory the photo evokes is more important than image quality, feel free to shoot the photo with your camera. It will be fine. But, if image quality is more important, your camera will not capture essential details, especially in the shadows or highlights, nor remove dirt and scratches. For high image quality and cleanup, you need a scanner.
KEY RULE: The purpose of a scan is to capture every possible pixel value in an image at as high a resolution as the source image provides. You want to lose as little detail as possible. Scanning does NOT create the look. You create looks by making a copy of the original scan, then tweaking it in a program like Photoshop.
For stills, I am a huge fan of the Epson Perfection V600 Photo scanner. I’ve owned one for years, it is reliable and excellent for photos and hand-written historical documents. It scans documents up to 8.5 x 11″.
Due to the generally poor quality of printed photos, especially amateur photos, I generally scan prints between 400 and 600 dpi. You can use higher resolutions, but all you’ll see is blur and grain. The actual scanned image size depends upon the size of the source image.
For slides, though the V600 is good, the Epson Perfection V850 Pro scanner is better. Why? It can scan up to three slides at the same time, thus saving time, and it has a much better dynamic range, meaning it can extract more detail from shadows or highlights than less expensive scanners.
NOTE: There are a few other good slide scanners. If you need image quality, avoid any scanner that only saves to JPEG format. JPEG, by definition, removes color and texture to reduce file size. You should also look for a “DMAX” number as close to 4 or better as possible. DMAX is a critical setting that elicits detail out of shadows.
The best resolution you can scan 35mm slides is 2400 dpi without seeing excessive film grain. You will never need any scanner resolution greater than 4800 dpi for 35mm slides or prints.
Professional photographers, shooting with large format cameras and delivering 8×10 negatives for scanning, may expect higher resolutions in their scans. But, I’ve never been lucky enough to get large format negatives, except for one 4×6 negative portrait shot in 1875. Not the same quality as a Vogue photo shoot, though.
I use LaserSoft’s SilverFast 9, because of the tools it contains. However, any professional-grade scanning software will have similar gray-scale tools. I view images using a BenQ PD2725U monitor set to 100% sRGB color space.
UNDERSTANDING BIT-DEPTH AND THE HISTOGRAM
While color wheels and video scopes are the tools of choice for video, the histogram and gray-scale sliders are the key tools for stills.
NOTE: While these techniques can be used in Photoshop and other image editors, I’m going to start with a scan to maximize the quality of the images I capture. Though not part of this tutorial, I also use the scanning software to crop any unwanted elements (like fingers) from the frame, remove any tilting because the camera was not held level, and correct any obvious color casts.
An 8-bit image always and only has a range of 256 gray-scale steps from pure black to pure white. Even if that image consists of one color, there are still 256 steps available to that image. (A 10-bit image has 1,024 steps, a 12-bit image has 4,096.)
Screenshot
When we move the sliders in the Histogram, we are reducing the range over which those 256 gray-scale steps apply. The number of steps doesn’t change, only the starting and ending values.
NOTE: Reducing the range – but keeping the same number of steps – amplifies the tiny differences in pixel values, meaning we can pull out detail that is not obvious to the naked eye. (You’ll see examples of this below.) Essentially, narrowing the range increases the scanner’s sensitivity to varying pixel values.
In the screenshot above, the left arrow indicates shadows, the middle arrow mid-tones (or mids) and the right arrow shows highlights. Also, in this example, the Histogram (the name for this window) shows most gray-scale values (the lumpy black shape) in the upper-half. Meaning there are no dark areas, shadows, in the image.
There are five sliders on a scanning histogram (five also in Photoshop – though NLEs only offer the top three):
EXAMPLE ONE – DARK
Here’s the image we will work with first. It’s dark. This was my one-and-only summer spent as a farm hand, bailing hay.
Most older images have a color cast, like the blue cast in the original image on the left. Most of the time I want to get rid of it. To do that, we need a gray or white reference that is NOT!! over-exposed. In this photo, I used my white T-shirt as a reference color.
Most scanners have a sampling tool we can use to select something that’s supposed to be gray or white and remove the color cast. (By definition, “gray” consists of equal amounts of red, green, and blue. This sampling tool determines the imbalance, then adjusts color values for the entire image so the RGB values balance.)
NOTE: The dust and blemishes you see are on the surface of the slide itself. Those can be removed during the scan using dirt removal software (ICE) built into most professional scanners. This is another advantage of using a scanner, rather than your camera. It dramatically cleans up an older image.
An exception to removing color casts are very old photos with a sepia tint. (Think “Old West” photos from the 1880’s.) That sepia tint adds legitimacy and age to the photo. I could remove it, but the photo would not look as believable.
Because most of the image of me on a tractor is dark, the black lumpy area, which represents pixel gray-scale values, slid to the left. I won’t move the Shadow slider, which would simply make dark areas darker, but will move the Highlight slider and Mids. Notice the Highlight slider is slightly inside the leading edge of the pixels. These values are in the sky, and I don’t care about sky texture. So, moving the Highlight slider just inside that right edge makes the image brighter, without losing any important texture.
Sliding the Mids slider redefines mid-tone gray. Sliding in one direction makes the image lighter without affecting highlights, while sliding in the opposite direction makes the image darker without affecting shadows. (Photoshop and SilveFast use the same slider for the same reason, but move it in opposite directions.)
Here’s the finished image – much brighter, more accurate color, with most of the dust and dirt gone. Remember, we are not going for a “look,” but to capture as much color and detail in the image as possible.
Because of this, I always save the images I’m going to edit as TIFF, or, in rare cases, PNG. If I’m not going to edit them, I’ll save them as PNG. Never, ever, ever save the original scan as JPEG.
EXAMPLE TWO – DARKER
This late-60’s prom dragon is really dark. How do we fix it?
Because I don’t want to lose any shadow detail, I leave the top Shadow slider alone. Because there are no highlights in the image – except for speculars on the door hinges which I don’t care about – I slide the Highlight slider right to the edge of where highlights start. I leave the Mids slider mostly in the same place; its default value is 0.
NOTE: Remember, in scanning, you want to capture all pixel values. Create the look after the scan is complete using a copy of the scanned image.
A new technique is that I raised the bottom-left slider (called: Minimal Highlights). This opens the shadows allowing us to see detail around the engine that would otherwise be lost. (Raising this too much make the shadows look “foggy;” moving this a little goes a long way.)
Finally, I tweaked both the Mids and the Minimal Highlights sliders until the image looked as rich as possible. Here’s the finished result.
EXAMPLE THREE – REALLY, REALLY DARK!
A LOT of these older slides look like this. Yeah, exposure was a tricky beast. So how do we fix this? Well, surprisingly we have two options: color and black-and-white.
Here’s the color version and histogram. Notice how high the black levels were raised? The Highlight slider was moved aggressively toward where the main pixel display curves up, because the leading edge represents white highlights on the collars of men in the audience.
But, sometimes if you stretch the color values too far, you may be better off converting it to black and white. Color in dark images often starts smearing. Switching to black-and-white solves this.
EXAMPLE FOUR – TOO LIGHT
Here, the entire image is too light. Now, as a caution, if a highlight is over-exposed, there’s nothing you can do to bring it back. But, if you can see details in the highlights, that can be recovered.
NOTE: Modern digital cameras that shoot log or raw media have a wealth of texture in their highlights. My examples are drawn exclusively from film which have none.
Because there are no dark areas in the image, we don’t want to adjust the Minimal Highlights slider, which would only lighten them.
Because the image is already too light, we don’t want to adjust the Highlight slider either.
Drag the Shadow slider slightly into the trailing edge of the histogram. Watch the image closely, you don’t want to lose any shadow detail, but the more you adjust this slider to the right, the richer the image will appear.
Finally, after adjusting the Shadow slider, drag the Mids slider to darken the overall image. Again, every image is different, but there will be a point where it looks good to you.
NOTE: Adjusting the Shadow or Highlight slider too far into the pixel display will lose detail. Dragging the Mids slider will adjust the look, but will never lose detail in the scanned image. So, be more conservative when adjusting the Shadow or Highlight sliders.
SUMMARY
Remember, our goal in scanning these images, is to capture every pixel value with as much texture and detail as possible. Once captured, we can bring them into Photoshop, or the image editor of choice, and make them look as we want.
These sliders work in concert to improve the look of an image.
If the image is too dark:
If the image is to light:
Above all, make sure your monitor is set to the sRGB color space and remember that even when it looks beautiful to you, the end user can still screw it up.
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2 Responses to How to Use a Scanner to Rescue a Too-Dark or Too-Light Still Image
You had quite the coiffure.
Yeah…. well, that’s what happens when Dad cuts your hair.
Larry