How to downsample an image to match a 16-bit color mode?


Question

NOTE: I'm a systems administrator, not a graphic designer, so I'm a total n00b when it comes to image manipulation.

That being said, I thought this would be the best forum to ask this question:
I am setting up a terminal server farm where the desktop shows our corporate branded background image. The problem is that the RDP session is limited to 16-bit color, and it creates a visible and annoying vignette pattern in the image which looks unprofessional.

Is there any way to downsample the image to a 16-bit color palette and use dithering to reduce the color banding in the image?

I'd rather use GIMP since it's free but I can borrow a computer with Photoshop in it if I have to.

----EDIT----

I cross-posted this question on Server Fault and got the following information:

"5/6/5 has always been how Windows has handled 16-bit video modes (at least, in my memory) so I'd be inclined to grab a Photoshop filter that dithers to 5/6/5 format and tweak from there."

Is there such a filter in Photoshop that I can use?

1
3
6/20/2014 7:28:00 PM

Is there any way to downsample the image to a 16-bit color palette and use dithering to reduce the color banding in the image?

Yes. Use Photoshop's "Indexed" mode. When you choose this option, you can pick the colors to use as well as whether or not to dither it (you want to dither it).

enter image description here

Image credit + more details: http://www.mediacollege.com/graphics/01/options-gif.html

2
6/20/2014 6:48:00 PM

Licensed under: CC-BY-SA with attribution
Not affiliated with: Stack Overflow
^