Some scanners will automatically perform a number of corrections on pictures, but it never hurts to be familiar with carrying out this touch-up process by hand. Your scanner software may not have such a feature, or you may not like the results. With Photoshop, you can make your scanned pictures look as they do in their printed form.
To illustrate this tutorial, I am going to use a photo I took with a disposable camera on a trip to France in 2000. Here is how the photo looks after being scanned, without any adjustments:
Not bad, but the colors are a little off, it lacks contrast, and the image appears soft. Time for a little touch-up work.
Fix the Colors
The fastest way to fix the colors in a scanned photo is to use Photoshop’s “Auto Color” adjustment. This adjustment usually does a great job of making the colors in a photo appear accurate and life-like. Click Image → Adjustments → Auto Color.
Here is my photo after having the Auto Color adjustment applied:
If you do not like the result of the Auto Color adustment, click Edit → Undo and try tweaking with the Levels tool instead. Click Image → Adjustment → Levels to bring up this tool.
I usually prefer to use the gray eyedropper to adjust levels. Click on the gray eyedropper button (the middle button circled in the screenshot below), and then click the eyedropper on a portion of your picture that should appear neutral gray.
By clicking on a gray point that is halfway between black and white, Photoshop can use that point as a reference to adjust all the other colors. If you do not get good results on the first try, just pick a slightly different shade of gray and try again.
Adjust Brightness and Contrast
The picture is getting better, but it is still dark and “flat”. This can be fixed in seconds with another of Photoshop’s adjustment tools… click Image → Adjustments → Brightness/Contrast. In this case, I increased the brightness by 15, and the contrast by 25. Here is the result:
Unfortunately, my adjustments to brightness and contrast have had a bad side effect — I have lost some detail in the both the darkest and brightest portions of the photo. Notice how the stone ledge appears almost white — that is a lack of detail in the highlights. Observe how some of the darkest trees in the upper left corner appear almost black — that is a lack of detail in the shadows.
Some of this detail can be recovered with the Shadow/Highlight adjustment (click Image → Adjustments → Shadow/Highlight…). Here is the photo after entering a Shadow amount of 3, and a Highlight amount of 15:
Sharpening
Finally, we must recover the sharpness that is lost in the scanning process. Click Filter → Sharpen → Unsharp Mask and adjust the Amount, Radius, and Threshold sliders. As you adjust these sliders, you will see sharp, distinct edges begin to emerge from what was previous a very “soft” photo.
It is hard to generalize the sharpening process, but going into excruciating detail about using the Unsharp Mask filter is also beyond the scope of this article. All photos are different. Let me just say that for a lot of the sharpening I do, I use an amount between 100 and 200, and radius between 0.3 and 0.7, and a threshold between 0 and 5. For this photo, I used amount: 180, radius: 0.7, and threshold: 0.
If you begin to see unnatural halos around elements in your photo, or it becomes very grainy, you are over-sharpening.
Here is the final result:
And here is the original, untouched scan for reference:
Quite a difference, eh? Many of the adjustments made to this photo were subtle, but even the most subtle differences can have a dramatic effect on how a person sees an image.
