In Illustrator, you can flatten layers to create a more even image. To flatten a layer, select it and click the Flatten Layer button. The Flatten Layer dialog box appears. In the Flatten Layer dialog box, you can choose how much to flatten the layer, how many layers to flatten, and whether to add a mask. To flatten a layer in one go:

  1. Select the layer you want to flattened and click the Flatten Layer button.
  2. The Flatten Layer dialog box appears.
  3. In the Flatten Layer dialog box, choose how much to flatten the layer, how many layers to flatten, and whether to add a mask if desired.