You can choose to preview the textures with one of several different sources. You can either view the texture by itself (the default), the texture as it would look applied to the current image, or the texture as it would look with one of the preset custom images. Use the “Preview With” drop-down-list at the top of the Texture Library to choose how you’d like to preview the textures in the grid.
Choosing the current image from the drop down list will cause Dirty Pictures to generate a preview for each texture in your library, one page at a time. This takes a few seconds, but gives you the most accurate preview of how the tones and details of the textures will interact with the actual photo you’re working on.
The custom image presets are useful in that they allow you to see the textures applied to actual photos, but since the preview images are cached, they only need to be generated once. Browsing your texture library with the custom images is therefore a lot faster than with the preview source set to the current image, and it can often give you just as good an idea of what the texture will look like.
You can also use the Favorites star to tag textures you like for easy access. Hitting Cancel will return you to the main window without selecting a texture.