3 replies to this topic

[BDBake]

Hello, I am doing my first comet stack and in creating the star image, several small galaxies were left behind which I would love to be in the final image.

So, I used the dynamic paintbrush tool to mask them from the original image. But I cannot figure out how to copy them over to the stars image. It's probably incredibly simple, but I'm just not seeing it.

Thanks in advance!!

[WadeH237]

I generally use PixelMath to combine images.

 

The correct way to do it depends heavily on the nature of the two images.

 

The simplest way is to just add them together.  This works if the comet image is completely black except for the comet, and the stars image is completely black except for the stars.  That expression would look like:

 

comet_image + stars_image

 

If there is significant background in both images, then you could combine them, keeping just the brightest pixels:

 

max(comet_image, stars_image)

 

Most of the time, when I separate the stars, I use StarXTerminator and descreen them.  The proper way to combine them back in is then to use the screen blend mode in PixelMath:

 

combine(comet_image, stars_image, op_screen())

 

There are countless other ways to do this, but it all depends on the specific relationship of the images that you are trying to combine.

[Dereksc]

Hello, I am doing my first comet stack and in creating the star image, several small galaxies were left behind which I would love to be in the final image.

So, I used the dynamic paintbrush tool to mask them from the original image. But I cannot figure out how to copy them over to the stars image. It's probably incredibly simple, but I'm just not seeing it.

Thanks in advance!!

 

If you generated a "stars_image" and a "comet_image" from your "original_image" using Starnet++ or StarXTerminator then the "comet_image" will contain background galxies. The simplest way to get them in your "stars_image" is to CloneStamp the galaxies OUT of your "comet_image" and then subtract the "new comet_image" from your "original_image" using pixel math. This will generate a "new stars_image" that contains stars and background galaxies:

 

stars_image_new = original_image - comet_image_new

 

Regards

 

Derek

[ComeAlongBort]

I really liked the method used in this video: https://www.youtube....h?v=SCMyGNZlx5o