The black and green boards apply a chalk effect to all images inserted within it. At the moment, this cannot be disabled. If you'd like the images to remain crisp, we recommend using either the white or glassboard background.
If this is not to your liking, you can choose a custom background instead. This lets you choose different colors or upload your own image as a background to mimic a blackboard or scene.
Note: After selecting a chalkboard background then switching into custom color, it actually retains the effect. If you want it removed without having to redo the scene, go into Settings and switch to whiteboard or glassboard and Save. From there, you can either stick with either glass or whiteboard, or use your preferred custom background.