A blog related to original AI artworks. I make AI artworks using coined words and emoji as prompts.

How far can you get night-scene images with a coined word close to “night”?

When using Stable Diffusion to draw a night view, we sometimes use a neologism similar to “night” as a prompt, such as “nigh” or “nite”. However, just using these neologisms does not necessarily result in a night view. Therefore, if the contrast of the resulting image is low, it is not always clear whether it is a night view or not.

I wrote in a blog post called “The Necessity of AI Image Editing and an Automatic Optimization Program for It” that images created by AI art programs need to be edited. I think that especially for night views, it is necessary to edit the images. If it is a night view, it is sufficient to increase the gamma value and make it darker to edit the image, but if it is not a night view, care must be taken not to increase the gamma value too much. Depending on the case, it may be necessary to adjust the brightness to make the light appear brighter, or conversely, if it is not a night view, it may be necessary to adjust the brightness to make the overall image brighter. It can be confusing to know what to do.

If streetlights or other light sources are depicted in the image, it is almost certainly a night view. In such cases, the image should be adjusted to be sufficiently dark. An example of such an image is shown below.

The same applies to indoor scenes. If it is dark outside and the lights are on, it can be inferred that it is night, so the image should be made sufficiently dark. (The lower right image may not be dark enough.)

However, if there is nothing that clearly indicates the time of day, it is difficult to know how bright the image should be.

For the last image above, it is clear that if the objects in the sky are stars, the image should be made darker, but it is not clear whether they are stars or not.

For indoor scenes as well, if there is no clear light source, it is difficult to know what the appropriate brightness should be.

In both of these images, the non-lighted parts are shining, but this is the result of increasing the gamma value and brightening the entire image. It is uncertain whether this is appropriate or not. If it is night, one way to make the image appear darker is to darken the entire image if there is no light, but doing so will make the impression of the picture fainter.

If you are unsure, I think the best thing to do is to decide on the brightness level that you think is best.