Understanding basic lighting prompts
Knowing how photographers use light is a great starting point for getting light right in AI portraits
It always amazes me when I see prompts on Midjourney that look like someone threw everything including the kitchen sink into it. For sure, some folks get stunning results from these prompts, but I’m guessing it’s more in spite of their prompt than because of it – especially when some of the prompts actually contradict each other.
While I’m a firm believer that you should do whatever works for you, I wanted to offer some thoughts from a photographer’s perspective on understanding lighting and how and when you might want to use particular prompts, especially in portraiture.
Here are the five types of basic lighting prompts we’ll look at:
Soft lighting
Warm lighting
Cool lighting
Harsh lighting
Dynamic lighting
Note: These examples were generated in Midjourney. I kept the prompt as simple as possible with only a sparse description of the scene in an attempt to isolate the impact of the lighting prompt.
Soft Lighting
In photography, when we talk about “soft lighting,” it’s often in the context of a light source that has been “modified.” Sometimes, this is because we’ve taken the light and placed a diffuser between it and the subject. When the light from a strobe is fired toward the diffuser (which can be a translucent fabric that is part of a soft box) the diffuser spreads the light out and “softens” it. There are many other ways light can be diffused, such as indirect light passing through a window or sunlight shining through vegetation.
Think of it in terms of a water hose that shoots out a strong, concentrated stream of water. That stream is hard and direct but you can twist the nozzle and spread the water out. Light works in a similar way.
With soft light, the shadows are not as harsh because the transition between light and darkness is smoother.
In the photo above of the old man on the sofa, the lamp shade actually works as a lighting modifier. Note how the shadows on his face have a smooth gradient. In the examples below, soft lighting in an outdoor setting typically means that the subject is in the shade or the light is early in the morning or late in the day, rather than harsh, overhead sunlight.
Suggested prompts: “soft lighting” “diffused light”
Warm Lighting
In photography when we describe light as “warm,” we’re not talking about whether the light is hot or cold, but where it falls on the Kelvin scale, which measures the color temperature of light. If light is on the low end of the scale, it is considered “warm,” producing light with an amber quality. Light on the cool side of the scale is more blue.
Thus, if we’re describing early morning light or late afternoon light, we often call it the “golden hour.” The period right after the sun goes down or right before it rises is often referred to as the “blue hour” because of the bluish quality of the light.
Also keep in mind that “soft lighting” and “warm lighting” are complementary to each other and can be used together (see the photo at the top of the page).
In the interior images below, the prompts were “photorealistic movie still of a young girl in a coffee shop + warm light” and “photorealistic movie still of a mexican man inside a church + warm light.” As you can see, there was no reference to time of day but the prompt put the scene into golden hour light. For the man, he’s inside a church and seems to be lit by a candle, which is warm light, as well as a window.
Suggested prompts: “warm lighting” “golden hour lighting” “golden light”
Cool Lighting
With the explanation of color temperature above, the thing to keep in mind is the type of light bulbs that are cool. Fluorescent lights are typically cool, while incandescent lights run warm. However, neon and LED lights can run the range from warm to cool.
The other thing to keep in mind is that in a street scene like the one above, you’re likely going to get a mix of lighting temperatures. In fact, the light on the side of her head is a bit warm, while the light on the front of her face is cool. For this to happen in reality, there would have to be two distinct lighting sources illuminating her – a warm sidelight and a cool overhead light.
I tend to get mixed results when I prompt “cool light.” Some of the initial images in the grid are always a bit more warm than cool. Using “bright white light” can produce better results, or even specifying “fluorescent lighting” or if it’s outside, prompting for “twilight.” Using “bright bluish light” can also work but beware that whenever naming a color in your prompt, the AI will usually incorporate it into the subject’s clothes or use it to color objects in the frame.
The prompts for the images below are “photorealistic movie still of a older man at a vegetable stand + bright bluish light” and “photorealistic movie still of a skinny man in the gym + bright white light.” (Note: I guess Midjourney considers “skinny” as 0 percent body fat and ripped.)
Suggested prompts: “cool lighting” “twilight” “bright white light” “bright bluish light” “fluorescent lighting” “blue hour light”
Harsh Lighting
While we tend to find warm and soft lighting more aesthetically pleasing, there are certainly times you want harsh or hard lighting. The midday sun is a harsh light. A bright, cooler light can be harsh. Hard lighting provides more contrast and will create deeper shadows, which can be very interesting in portraits.
You can also add a modifier such as “overhead” or “midday” to juice the results a bit. Harsh or hard light is also a great light to use with black and white images where you might want more contrast and deeper shadows.
The prompts for the images below are “photorealistic movie still of a man working on a roof + harsh overhead midday light” and “photorealistic movie still of an older woman on miami beach + harsh overhead lighting” and “photorealistic black and white movie still of man standing in an alleyway + harsh lighting.”
Suggested prompts: “harsh lighting” “hard lighting” “harsh overhead lighting” “harsh midday lighting” “harsh overhead midday light”
Dynamic Lighting
And finally, here’s one of my favorite lighting prompts – dynamic lighting. Sometimes I use this in combination with other lighting prompts, but it can produce some fantastic results when used by itself, as well.
Defining dynamic lighting isn’t easy. The word "dynamic” implies movement, adaptability, progression. When applied to lighting, it can mean that the light changes to fit a space or scene.
Of course, what matters isn’t how we define dynamic but how the AI defines it. In my experiments with the prompt in Midjourney, one of the things I notice is that it often returns images with multiple light sources, along with interesting shadows.
Because dynamic lighting isn’t easily defined, it introduces an element of randomness into generated images. I also think it’s closely related to “dramatic lighting” and the prompts can often be used interchangeably with similar results. Both terms can also be used in combination with any of the other lighting prompts we’ve gone over.
The prompts for the images below are “photorealistic movie still of a black woman on a los angeles street + dynamic lighting” and “photorealistic movie still of an iranian woman in a laboratory + dynamic lighting”
Suggested prompts: “dynamic lighting” “dramatic lighting”
All images were generated by Joe Newman using the Midjourney platform. You can also follow along on Instagram at @most_sublime_media. Get fresh content delivered to your inbox by subscribing to our Substack newsletter.