Quick Meditation Question on Visualization

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I have been working on counting breaths and visual meditation.

What exactly does visual mean when it comes to meditation. I can *think* about an image, but not actually see it. I cannot form a red triangle in my mind, for example. All I see is darkness with random white patches.

Do you actually see things during a visual meditation, or just think about them? Like when people use guided meditation to see their deity or whatever, it doesn’t make sense to me.

I appreciate any help. Thanks!