Upscaling Grayscale

Although it’s eminently preferable to scan all your old photos in color, sometimes we don’t have the luxury of that choice. Sometimes we only have access to grayscale scans of photos, for whatever reason – even portions of the wonderful old photographic collections in the Library of Congress were, unfortunately, scanned in grayscale. Even though the color channels are, at their core, channels of ‘color’, even black & white photos have differences in the separate channels in the form of tones.

I’m often asked to estimate a digital photo restoration by analyzing scanned photos – when the client can’t bring the photo to me, they can always send the photo via email (ain’t technology grand?). When telling the client what I need from them, I always ask them to scan the photo in color, yes, even the black and white ones! The reason for this is simple: Scanning a photo in color allows you to take advantage of one of the bright stars in the Photoshop universe, color channels.

What are color channels, and why are they so important to digital photo restoration? Unless you’re going to be doing some pretty intense professional printing, the channels you’ll most likely be working in is RGB, or the Red, Green and Blue color space. Think of the channels as a sort of sandwich; the red and blue channels are the bread and the green channel is sandwiched in the middle (Fig. 1A, below) When you look at the channels palette itself, you’ll see not three channels, but four. The fourth, or, technically, the first, is the combination of the three colors, the actual RGB channel.

 

 

You can opt to show the channels in color (Edit > Preferences > Interface > Show Channels in Color), but the greatest benefit in channels to digital photo restoration is in keeping the channels in their default state, which is black and white. Each channel has it’s own depth of color and the damage in the photo is often greater in one channel, less in another. In that regard it’s a great evaluation tool. If needed, you can take out the most damaged channel, but that’s a tutorial for another time. If your photo is in greyscale, you can also ‘rebuild’ your channels in order to add depth to your photo (Fig. 2A, above).

 

This photo, though fine in grayscale, could most certainly be better. Pure grayscale images are generally rather flat and, sometimes, somewhat harsh. I’ve found, over the years, it’s almost universally preferable to do some tonal tuneups on black and white restorations.

 

 

An image scanned in grayscale will only have one channel because the color information will have been stripped.

 

 

The first thing you should do when bringing a flat, grayscale image into Photo shop is change the color mode to RGB by going to the Image menu and then selecting Mode. You’ll see in the popout menu that Grayscale is checked. Go down a ways and select RGB Color. Now you’ll have three colors channels, but they’ll still all be the same. In order to give you added depth, you can actually make your own color channels! Start by selecting the Red Channel in the Channel Palette.

 

 

Go back to the Image menu and select Apply Image towards the bottom. You can also select your channels directly from the Apply Image screen, right in the area marked, oddly enough, Channel! Start by leaving the Blending mode at Multiply. You can always experiment with other blending modes later, in fact, I encourage it, but this is a good place to start. Set the Opacity level to 25% and hit OK.

 

 

Select the Green Channel, either from the Channel Palette or Apply Image. In the Apply Image menu, change the Opacity level to 50% and hit OK.

 

 

Repeat with the Blue Channel, using 75% as your Opacity. Select OK.

 

 

You now have rebuilt color channels in your previously flattened photo. This gives you a great place to either start your restoration, or, in some cases, a really nice sepia tone!

 

 

Being as how this is an article on making better Black & White images, however, I’ll point out the big benefit in this exercise, in this instance, is you’ve brought back the ability to now use the Black & White Adjustment Filters on your image!

 

 

To achieve a nice Duotone look, pick a strong Black & White Adjustment filter, such as Maximum Black, and take the opacity down to around 75% so just a hint of the Sepia Tone comes through.

 

 

In the next couple of weeks, we’ll explore a couple other ways to make better Black & White restorations!

 

 

 

 

 

 

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Janine Smith is an award winning restorationist. For more of her work and tips, visit her website or why not chat to her on Twitter?