This is a fairly straight studio shot taken with my Sigma 50mm Macro lens of gladiolas in a vase. I converted it to LAB Color in Photoshop, and then inverted the Luminosity (L) channel (by making sure only the L channel was selected in the Channels palette, and choosing Image > Adjustments > Invert). This essentially had the impact of turning the seamless white background to black without changing the other color values in the image.
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