RSS/Atom feed Twitter
Site is read-only, email is disabled
  1. Chat
  2. Useful links
  3. Polls

Featured content

Using channels to select pixels

This discussion is connected to the gimp-user-list.gnome.org mailing list which is provided by the GIMP developers and not related to gimpusers.com.

This is a read-only list on gimpusers.com so this discussion thread is read-only, too.

6 of 6 messages available
Toggle history

Please log in to manage your subscriptions.
Using channels to select pixels bobdobbs 28 Jul 14:37
  Using channels to select pixels Rob Antonishen 28 Jul 14:48
   Using channels to select pixels bobdobbs 28 Jul 16:03
    Using channels to select pixels Rob Antonishen 28 Jul 17:40
  Using channels to select pixels saulgoode@flashingtwelve.brickfilms.com 28 Jul 15:54
   Using channels to select pixels saulgoode@flashingtwelve.brickfilms.com 28 Jul 15:58
bobdobbs
2010-07-28 14:37:19 UTC (over 14 years ago)
postings
31

Using channels to select pixels

Hello again guys.

I'm working through a tutorial made by photoshop:

http://colorburned.com/2010/07/create-a-refreshing-beer-themed-poster-design-in-photoshop.html?utm_source=feedburner&utm_medium=email&utm_campaign=Feed:+Colorburned+(Colorburned+|+Graphic+design+resources,+tutorials,+and+more!)

Step 24 is interesting. Water spray is seperated from a background colour, using a manipulation of channels.

I can't seem to figure out how to the same thing in gimp. Any idea how I can do it?

Rob Antonishen
2010-07-28 14:48:50 UTC (over 14 years ago)

Using channels to select pixels

Step 24 is interesting. Water spray is seperated from a background colour, using a manipulation of channels.

I can't seem to figure out how to the same thing in gimp. Any idea how I can do it?

There may be an easier way, but what I will do is decompose the layer to a new image. Identify the decomposed layer that gives the best match to the desired selection, then drag that layer into the channel panel of your original image. You can then load it as a selection, and further use quickmask mode to tweak it.

-Rob A>

saulgoode@flashingtwelve.brickfilms.com
2010-07-28 15:54:47 UTC (over 14 years ago)

Using channels to select pixels

Quoting bob :

I'm working through a tutorial made by photoshop: :
:
Step 24 is interesting. Water spray is seperated from a background colour, using a manipulation of channels.

I can't seem to figure out how to the same thing in gimp. Any idea how I can do it?

The process is fairly similar for GIMP.

1. Open your Channels Dialog ("Windows->Dockable Dialogs->Channels") 2. Click and release once on the thumbnail preview of the color channel which offers the highest contrast. (see Note below) 3. Hold down the mouse button (while over the preview thumbnail), drag the channel to the window in the lower part of the dialog, and release the mouse button.
4. Click on the red, square button at the bottom of the dialog to turn the recently dropped channel into a selection. 5. Go back to your Layers Dialog and continue with the tutorial.

Note: The Step #2 is necessary because clicking on the thumbnail toggles whether the channel is active (highlighted). In this case, the first click (in Step #2) disables the channel; while the second click (in Step #3) re-enables it. Basically, you just want to ensure that all your channels are active (highlighted) after doing your drag-n-drop.

saulgoode@flashingtwelve.brickfilms.com
2010-07-28 15:58:36 UTC (over 14 years ago)

Using channels to select pixels

Forget everything I posted (sorry). Here is an easier way:

1. Open your Channels Dialog ("Windows->Dockable Dialogs->Channels") 2. Right-click on the preview of the channel with the highest contrast and select the "Channel to selection" command.

Quoting saulgoode@flashingtwelve.brickfilms.com:

Quoting bob :

I'm working through a tutorial made by photoshop: :
:
Step 24 is interesting. Water spray is seperated from a background colour, using a manipulation of channels.

I can't seem to figure out how to the same thing in gimp. Any idea how I can do it?

The process is fairly similar for GIMP.

1. Open your Channels Dialog ("Windows->Dockable Dialogs->Channels") 2. Click and release once on the thumbnail preview of the color channel which offers the highest contrast. (see Note below) 3. Hold down the mouse button (while over the preview thumbnail), drag the channel to the window in the lower part of the dialog, and release the mouse button.
4. Click on the red, square button at the bottom of the dialog to turn the recently dropped channel into a selection. 5. Go back to your Layers Dialog and continue with the tutorial.

Note: The Step #2 is necessary because clicking on the thumbnail toggles whether the channel is active (highlighted). In this case, the first click (in Step #2) disables the channel; while the second click (in Step #3) re-enables it. Basically, you just want to ensure that all your channels are active (highlighted) after doing your drag-n-drop.

bobdobbs
2010-07-28 16:03:08 UTC (over 14 years ago)
postings
31

Using channels to select pixels

What are you describing goes beyond my comprehension of gimp. If you have the time, I'd love it if you could break that down for me.

Decomposition was simple enough once I'd figured it out.

After I read you email, I looked up the docs to discover what quickmask is, and I think I understand that.

But I'm afraid that I couldn't figure out how to drag a channel of the newly decomposed image into the channels panel of the original image.

Rob Antonishen
2010-07-28 17:40:43 UTC (over 14 years ago)

Using channels to select pixels

What are you describing goes beyond my comprehension of gimp. If you have the

time, I'd love it if you could break that down for me.

Decomposition was simple enough once I'd figured it out.

I think SG's solution is simplest to use.

-Rob A>