Cannot Extract Red Channel

[pbyrne]

Hi there.

I took about 2 hours worth of H-Alpha images last night.  I went to process them today, they all came out red from DSS, as expected, but when I tried to extract the red channel in Photoshop 2021 and paste to a new image, the new image was the same as the old, ie, all the colour channels were extracted, not just the red.  I have extracted the red channel before with my set up, why is it not working this time?  The file is a 16 bit tif file.  One other problem, when I step out of Photoshop, to go onto Google, etc, Photoshop freezes, why is this happening?

I know learning astrophotography is a steep learning curve, but I didn't realise I would be scaling Everest.

Thanks

[newbie alert]

Are you trying to extract the red from a HA image with a colour cam?

Edited October 10, 2021 by newbie alert
Adjusted

[symmetal]

The quickest way to extract channels is to Load the RGB image as normal. Click on 'Channels' tab. Click on the 4 horiz bars icon to the right of the Channels tab label and select 'Split Channels' from the drop down menu. Your image will be split into 3 separate images on screen. Then just save the Red titled image. This will be a greyscale image of just the red channel.

As to why Photoshop is freezing suggests insufficient RAM and/or Disk Swap space. If you have more than one hard disk, in Edit/Preferences/Scratch Disks tick any unticked disks so Photoshop can use them too. You'll need to restart PS after doing this.

Alan

 

Edited October 10, 2021 by symmetal

[symmetal]

An alternative method using Copy/paste is

Load RGB image as normal.

Hit Ctrl+3 To display Red Channel. Or go via Channels tab and select Red channel.

Hit Ctrl+A or Menu Select/All to select all the image.

Hit Ctrl+C or Menu Edit/Copy to copy it to clipboard.

Hit Ctrl+N or Menu option File/New. The clipboard should be highlighted so click Create, or hit Enter to create blank image of clipboard size.

Hit Ctrl+V or Menu Edit/Paste to paste the clipboard to the new image.

Hit Ctrl+E or Menu Layer/Merge Layers to merge the newly pasted image with the blank background.

Save new image.

When you get used to the keyboard shortcuts it's very quick. 😀

Alan

[pbyrne]

Alan, thanks for the info, it worked a charm.

No doubt I will be back here many times with a thousand and one more questions.

Thanks to you all for replying.