Triangle pattern
You need a picture, no matter if color or grayscale, no matter if picture or screenshot, everything works.
https://tool.itslitho.com/UploadImg
You can change Min Thick and Max Thick and also the mm per pixel Quality options.
A Min Thick of 0.6 or 0.8 mm is recommened especially if the picture has big light areas.
Less than 5€ for two night lamps