Cyber Corner

Scanning Graphite (and you thought watercolor was hard…)

By Deborah Shaw

Originally appeared in The Botanical Artist - Volume 17, Issue 2


I receive a lot of questions regarding problems with scanning watercolor or colored pencil. The artists I know who work in graphite, however, seem to have the most problems getting great scans.

Just as with artwork in full color, I always recommend having graphite work professionally scanned. I’ll use my desktop scanner as a working tool to check my artwork as I progress, but if I am submitting a piece to show, or if an artist wants to make prints, I always recommend having the work professionally scanned.

A sampling of the most common problems graphite artists encounter (and their possible solutions) are as follows:

My lightest values disappear.

Your scanning service really needs to know what she or he is doing in order to get a great graphite scan. If you just slap a graphite artwork on a flatbed scanner and hit the button, the software will “average” all the tonal values for the scan. So, in addition to relying on an operator’s scanning artistry, here is where good software can come to the rescue.

The truth is, optics on high-end flatbed scanners haven’t improved much over the last few years. What has improved is the scanning software. The gold standard in scanning software (as of this writing) is by SilverFast. SilverFast now has the ability to do multiple scans of the same artwork, combining those scans to get a full tonal range. Scans can be done with up to eight passes on the same piece of artwork. In recent testing, four passes seemed to provide the maximum benefit on the test artwork (each piece may vary). In a four pass scan, one pass takes an average of the full tonal range; another scans the darkest tones; another the midtones; and another the lightest tonal values. Neither I, nor my scanner operator, could see any difference between the four pass scan and an eight pass scan on the test. Of course, time = money, so a multi-pass scan will be more expensive than a single pass scan.

If your scanning service doesn’t have the latest SilverFast software, they can “pre-scan” the artwork, manually adjust the curve for the darks, midtones, and light tones (and all the important points in between) and then scan the artwork to match those values.

My scans come out with a purple cast.

Some scanning services scan graphite in RGB (red, green, blue) color in the belief they will get a broader value range. They may then convert the color scan to grayscale, or they may leave the scan in RGB mode. Hence the purple cast. I’ve found in tests that scanning in RGB mode frequently destroys detail in the darkest areas. Your scanning service should be able to get great scans in Grayscale mode.

My darkest darks have bright, light spots in them.

Graphite is shiny by nature. Depending on the type of scanner, the light can reflect off the darkest tones like a mirror, creating a hot spot like the flash of a camera on a window. If your artwork is large, or if your darks are causing reflections, the best digital capture method may be a copy stand. A copy stand uses a high-end digital camera with an extremely sharp lens and maximum resolution. Perfectly even lighting is key to great copy stand work. I’ve been told that the bulbs in the light sources need to be replaced frequently, tested often, and even be the same age.

Other issues:

One other important item to check: make sure your scanning service is using the highest optical resolution you need. Many inexpensive scanning services scan at a lower resolution and then use (bad) software to “interpolate” (i.e., “invent”) the pixels that are missing to create a higher resolution. You want to capture the information you’ve thoughtfully placed in your art – you don’t want their computer to be making up the details for you!