Maximizing Colour during Post-Scan Editing

Version 1.1, Page 3, ©2002 by Dale Cotton, all rights reserved.

Fig 4. Channel Palette showing duplicated blue channel

• 4. Switch to the normal exposure scan, open the channels palette, drag the blue channel down to the folded corner icon (circled in red) to duplicate it, click the RGB channel to reactivate, switch to the layers palette and click the layer to reactivate it.

If this seems mysterious, hang in there a moment longer.

• 5. Arrange the Photoshop window so both the normal scan and the +2 scan are showing with the +2 scan on top. Click on the Move tool, use it to Shift-drag the +2 scan on to any portion of the normal exposure scan. This creates a new layer to the normal exposure image containing the +2 scan.

Fig 5. Blue channel copy as a selection

• 6. Select the duplicate blue channel we made in step 4, Ctrl-click on the miniature image (circled in red) to create a selection from it, click RGB channel and layer 1 to activate both.

Fig 6. Converting the blue channel selection into a mask

• 7. From the Layer menu choose Layer as Mask, then Reveal Selection.

This is the method behind the madness of steps 4, 5, and 6. What we've done is hide every part of the normal exposure layer to the degree that it appears black in the mask created from the blue channel copy. This is one of several avenues to contrast enhancement available in Photoshop. In less extreme cases - ones in which you don't need to combine two separate scans - you can use Apply Image with a mask and a blending mode or create a contrast mask to ferret out sky or shadow colour from a single image.

• 8. Crop away the white and black non-image border.

Until the two exposures were safely married we had to leave them un-cropped to ensure registration.