One of the most difficult issues we face when creating a Virtual Vision file is to have shadows properly integrated with both color and patterns. Frequency separation is a technique used by Photoshop artists to clean up photos while maintaining the textures. We'll be using this technique to keep the shadows (and some texture) of the photos. This will also help us create shadow channels from images with colored fabrics (blue, yellow, green, etc.).
- Create a selection (or multiple selections) for all the objects we'll use. It's easier to create a selection for each fabric/object (a selection for a sofa and another for the curtains, for example).
- Duplicate the layer twice and hide the top layer, for now, we'll be working on the middle layer.
- Load the selection and use the filter Blur | Median blur (Desenfocar | Media). This will fill all our selections with the median color of the selection. If we have different objects (sofas, curtains, etc.) with different colors, we should select and blur each object independently.
- Show and select the top layer. Open the menu Image | Apply image. Select the blurred layer on Layer and Subtract (Restart) on Blending mode.
For 8-bit images, the values for Scale and Offset are 2 / 128. For 16-bit images, we have to select Add as blending mode and 2 / 0 as Scale and Offset.
- When we click Ok, it will create a light and shadow layer. If we change the blending mode to Linear light (luz lineal), we'll be able to see how it mixes with the blurred layer. To delete any remaining color on this layer and transfer it properly to a channel, we can open the menu Image | Hue / Saturation and set Saturation at 0. If the shadows look too light, we can increase the contrast with Image | Light / Contrast until we're satisfied.
- Original image
- Median-blurred file
- Generated shadow image
- We can now create a new channel for Shadows and select it. We go to Image | Apply image and select the shadow layer and Blending mode Normal.
- We can now delete these two layers and open Virtual Vision to create an object to work with this shadow. When selecting this layer, the result will be very dark, we'll have to set the Lights at 50%.
- We can use different colors to adjust the Brightness. It's usually faster to first use pure white and then some very bright colors.