If you are using 2D-textures you can easily adapt the color in photoshop. That will give the best results. If you want to do it in bryce you can change the colors of the procedural by clicking on the second round button on the top of the texture channel. That should get you to the DTE. In the DTE you can ALT-click the colored dot's and adjust the colors to your liking. If you want to use a single color over a texture you can set it by ALT-clicking on the color-dot at the right of the diffusion, ambience, spec etc channels. Then you can click the tiny little triangle at the bottom right of the texture channel (where you set the mapping modes). you will find there's an option named 'decal colors' click it and your texture will get the color of the color-dot mixed through it.

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