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

@Tiffany317

Another approach to this that's similar in principle to the one DA01 pointed out, but possibly a bit easier to control and work with:

In Photoshop, apply Layer > New Adjustment Layer > Posterize and adjust the slider. The 256 color option gives the smoothest rendering and is ready for 8-bit png or gif after you've added a little noise to smooth out visible banding.

To add the noise add a new layer (Layer > New Layer) filled with 50% grey and set to Overlay blend mode. Use Uniform noise, set to Monochromatic and an amount of 2% or so.

Then File > Save for Web and choose 8-bit png or gif at 256 colors.

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@Caterina889

I found the solution on this Adobe community forum. Not exactly what I was looking for but it looks good just the same.

Basically, I added noise to the picture so that the bands are less obvious when I indexed it to a 256-color palette. It's practically indistinguishable from the original now (although the company logo lost a bit of sharpness).

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@Holmes874

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).



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

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