How can I correct color banding in windows phone 7?

Question

My windows phone 7 app has very nice background images but they are being destroyed by color banding on a 16bit color device. Is there a way I can correct this? I have tried

Answer 1

You need to use dithering. Floyd-Steinberg is a good algorithm that is simple and runs fast.

You don't need to go to 8 bits per pixel as suggested by another answer, you can go directly to 16 bits per pixel. You need to know how it is split into R/G/B before you begin.

Here are some examples, first up is the original 24-bit:

Next is a 16-bit without dithering:

Finally 16-bit with Floyd-Steinberg dithering.

P.S. I did this with Paint Shop Pro, I don't know if Photoshop has anything similar. You can do it in code as well.

Answer 2

Here you go if you have Photoshop.

Photoshop Action for Windows Phone 7 Dithering

The "download"-image link is broken. So use the download link in the "How to Install and Use It" list.

Answer 3

If I set the mode to 8bit and dither using the "web palette" this creates a pretty good result. This is MUCH better looking than the banded image. However I will probably end up with 2 versions of the background image. One for 16 bit and one for 24 bit and above.

Answer 4

The solution is to not use gradients directly.
There is no way round this with the colours supported by the device.

The alternative is to create a dithered image and use that instead.