How to seperate a photo into layers (or channels?) by color

[Guest]

I am trying to split a photo (actually about two dozen photos into seperate layers (or channels) by color.  I want to take photographs that have an infinate number of colors and turn them into images with a finite number of colors (I'm thinking around 20).  I have experience using photoshop to clean photographs and enhance photographs but not this.  Having said that, I have been trying to do this for a couple of years now.  I was told ~two years ago that my problem was that I had two versions of phoroshop on my computer and it was screwing things up.  A month ago I bought a new windows 10 computer and a copy of photoshop 5.5.  I have tried to follow several online sets of instructions on how to do this and none work.  I assume I am not doing something basic that everyone knows (everyone but me) knows to do.  please help

[Chuck Uebele]

You can try using index color.

[Guest]

What are index colors?

[JJMack]

Photoshop only supports up to 8,000 layers where 8bit color supports 16,000,000 colors. 20 colors is poor GIF will go up the 256 mapped colors.  You can do 20 color into GIF files.  Then you may be able to use photoshop tools on the gif  files to separate your 20 colors,

[Guest]

I have no idea what you just said.  I need instructions like

1.  Select_______________

2.  do this (click)

3.  do this (right click)

4. select____________________

5, do this (click)

[JJMack]

If you convert an image to have just 20 colors via color index.  You can then make 20 Color selection. and create 20 layers that you fill the selections with a selected color.  You will have you image in 20 colored layers.  If you do not know how to make selection create layers and fill selections you need learn how to use Photoshop.

[Warren Heaton]

You don't need to promote each color channel to a layer to reduce the image to 20 colors.

Choose Image > Mode > Indexed Color.

PS2020 - Image > Mode > Indexed Color

In the Indexed Color dialog box, se the Colors to 20.  Adust the other settings as needed.

Index Color with Colors set to 20

After downsampling to Indexed Color, you can set the document back to RGB if desired and keep the reduced color in RBG color space.

It's fine to have more than one verison of Photoshop installed at the same time. 

[Guest]

I will try this.  Thank you.

[jane-e]

"A month ago I bought a new windows 10 computer and a copy of photoshop 5.5."

Hi

Where did you buy a copy of Photoshop 5.5 a month ago? It is no longer being sold by Adobe.

[Guest]

The photoshop 5.5 was laying around