Adjusting the tonal balance



Dark images from bronze coins are not merely a common problem, they are pretty much standard fare. The problem is not due to brightness settings on either the scanner or the monitor, and a dark scan will not be fixed by adjusting the brightness and contrast controls alone. The problem has to do with the natural tonality of bronze and the need for tonal balance in its imaging.

The next steps are the key to getting the coin's brightness where you want it. Using the mapping menu, skip the brightness control and go for the TONE control.

Tonal Balance

The tone map tool acts rather like a tone control in an audio system. You are going to make adjustments to the highlights and shadows to get the balance where you want it. These adjustments are best done by "sight." Notice that with the setting of 28% detail loss in the highlights and 1% detail loss in the shadows, the image takes on a much more natural level of brightness and tonality.

Overexposed

However, increasing the highlight value causes the coin to appear overexposed. The slight increase in the shadows, coupled with the increase in the highlights, causes the image to appear too contrasty.

Underexposed

On the other hand, raising the shadow value and dropping the highlight value darkens the overall "exposure." When you are satisfied with the tonal balance that seems most natural to you, click on OK and prepare to sharpen the image detail.


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