rgb to grayscale

[gerry]

I used to teach photoshop at a local community college and reading through one of my books I came upon the best way to covert rgb to grayscale.

To see the difference try converting a rgb image to grayscale using the two methods below.

Take a good rgb image and go directly to grayscale.

Take the same photo before the conversion and convert from rgb to lab, then go to channels and select the lightness channel, then drop out the colors by converting to grayscale.

Compare.

If you have not done this before, you'll be amazed at the difference.

[Pekka]

Yep, thanks for bringing that info up. I've used that method a lot and you do get a much better grayscale. I used it e.g. in http://photography-on-the.net/forum/showthread.php?t=1158#4459

[Don Ellis]

Wonderful advice...but a day late. I spent yesterday afternoon converting 10 infrared images to grayscale, and then applying duo-, tri- and quadtones to them before uploading them to my site. I now have forty photos that are going to have to wait for an upgrade :-)

One thought for people wanting to compare: If you're having trouble detecting the differences side by side, I suggest that you convert a file using both methods and then go to a program like ACDSee (any version), select both files (or put them in a separate directory), hit Enter to make one of them full-screen, and then use PgUp/PgDn (on a PC) to flip back and forth between them.

The differences manage to be both subtle and dramatic.

[Time passes]

It's 4am and all 40 images have been re-processed and reloaded. Now I know I'm going to remember this tip. Thanks very much for the advice.

[beach512]

Gerry -
Great tip and thanks.
I did see a big difference and I like the one from Lab better than just the grayscale one.

Dave