I’m trying to create a semi transparent effect of the night sky like the attached image on the left. The background is gray so it’s actually transparent at the top.
Ignore the rocket ship. The final image will have text and is for a t-shirt design. The mockup is how it would look on a black shirt.
Answer
If the T-shirt is to be screen printed, then you’ll need colour separations. So, add two spot colour channels to the image, one white, and one blue.
Then add a simple gradient to the blue channel, and paint some white dots of various sizes in the white channel. In the example below, I added a grey background layer so that the gradient and stars can be seen. You could delete the grey background layer afterwards.
Attribution
Source : Link , Question Author : Hillary , Answer Author : Billy Kerr