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This short tutorial will demonstrate one way of printing blacks with Piezography®BW without compromising all the wonderful gray values that are unique to this system.
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| One of the most noticeable qualities of Piezography®BW is its endless shadow detail. This asset often prevents users from perceiving that they are printing black. In the example above, the eyedropper tool indicates that the darkest pixels on the black rock are 86%. That tonal value would normally print as black or very near black with non-Piezography®BW systems. Piezography®BW on the other hand, can differentiate gray values all the way to 99%, with only 100% actually being black. |
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Examining the file above, using the Levels tool, reveals that there isn't actually any black, or even any near black pixels within the image. Moving the black point in from the left into a small "mountain" of the darkest pixels would convert them to black, but it would also darken the remainder of the image. This is not a recommended action, unless the entire image needs darkening. Try the following technique instead. |
Technique: Use the image to mask itself to apply contrast to the shadows.
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| Click on the "Load channel as selection" to turn the entire Grayscale channel into a selection. |
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Once the channel has been turned into a selection it can be edited in Quick Mask mode. Follow the example by clicking on the Quick Mask icon. |
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| Clicking on the Quick Mask icon makes the selection an editable Alpha Channel called the Quick Mask. It will have a red overlay appearance unless you make the Gray channel invisible as in the example above. |
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Now that you can edit the Quick Mask, use Curves to eliminate all image data except for the shadow areas. In the Curves dialogue example above, the 3/4, midpoint and highlight tones have all been eliminated and the shadow areas have been turned nearly black. As you experiment with this technique, do not hesitate to use any of the Photoshop tools to edit your Quick Mask to accomplish your purpose: to create a selection for the areas you want to apply local contrast corrections to. |
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| Because the white area above will actually become the selection, it must be inverted so that the shadows become the white area. Select Invert from the Image/Adjust menu. |
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Now that the Quick Mask has been inverted, click on the "Edit in Standard Mode" icon to turn the Quick Mask back into a selection. |
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| Now with the shadow area selection active, you can use Levels to move the black point in, which will effectively darken the shadows without darkening the mid-tones or even the 3/4 tones. Do this with subtlety. In the example above the eyedropper shows that an area which was 85% is now 100% - or black. The tones below 85% will be near black and if you made the Quick Mask with subtle edges, it will not be noticeable where the darks meld into the 3/4 tones.
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Although this may accomplish bringing much larger degrees of black into your images, it may also prevent you from exploring the greatest asset of Piezography®BW which is a dynamic range that is closer to the human eye than traditional photography.
Traditional black & white photographic film and paper have a sensitivity that naturally promotes shadows which tend to black, but it does so at the expense of shadow detail.With careful use of this technique you should be able to keep the best of both worlds.
©Copyright 2000 Cone Editions Press, Ltd. - All Rights Reserved.
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